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‌SPECIFICATIONS‌

ACCESSORIES & EQUIPMENT

Cellular, Entertainment, and Navigation - Volt

FASTENER SPECIFICATIONS

Reusable Threaded Fastener Tightening Specifications

SCHEMATIC WIRING DIAGRAMS

RADIO/NAVIGATION SYSTEM WIRING SCHEMATICS

Power, Ground, Antenna and Data Communication

Fig. 1: Power, Ground, Antenna and Data Communication Courtesy of GENERAL MOTORS COMPANY

Amplifier Inputs (UQA)

Fig. 2: Amplifier Inputs (UQA)

Courtesy of GENERAL MOTORS COMPANY

Auxiliary Audio Input

Fig. 3: Auxiliary Audio Input

Courtesy of GENERAL MOTORS COMPANY

Info Display

Fig. 4: Info Display

Courtesy of GENERAL MOTORS COMPANY

Speakers (UQA)

Fig. 5: Speakers (UQA)

Courtesy of GENERAL MOTORS COMPANY

Speakers (UZ6)

Fig. 6: Speakers (UZ6)

Courtesy of GENERAL MOTORS COMPANY ONSTAR/TELEMATICS WIRING SCHEMATICS

OnStar Schematics

Fig. 7: OnStar Schematics

Courtesy of GENERAL MOTORS COMPANY CELLULAR TELEPHONE WIRING SCHEMATICS

Cellular Telephone Microphone (-UE1)

Fig. 8: Cellular Telephone Microphone (-UE1) Courtesy of GENERAL MOTORS COMPANY

DIAGNOSTIC INFORMATION AND PROCEDURES

DTC B0997: AUXILIARY ELECTRONIC CONTROL UNIT PERFORMANCE

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Refer to Diagnostic Procedure Instructions to provide an overview of each diagnostic category.

DTC Descriptor

DTC B0997 3A

Auxiliary Electronic Control Unit Performance Incorrect Component Installed

DTC B0997 39

Auxiliary Electronic Control Unit Performance Internal Electronic Failure

Circuit/System Description

The info display module monitors itself for internal failures and reports its condition to the Human Machine Interface Control Module when requested. The info display also reports electronic identification information when requested.

Conditions for Running DTC

Ignition is ON or in the ACC position The system voltage is 9-16 V

DTC B101E is not set as current in the Human Machine Interface Control Module The test is run once during Human Machine Interface Control Module wake up

Conditions for Setting the DTC

B0997 3A

The Info Display Module has reported identification information that differs from the information calibrated in the Human Machine Interface Control Module.

B0997 39

The Info Display Module reports an internal malfunction.

Action Taken When DTC Sets

The Human Machine Interface Control Module will set the DTC and the Info Display Module will have limited or no functionality.

Conditions for Clearing the DTC

The Human Machine Interface Control Module detects a compatible Info Display Module with no internal malfunctions reported.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Vehicle in Service Mode, Infotainment system ON.

2. Verify DTC B101E is not set

If DTC B101E is set

Refer to Diagnostic Trouble Code (DTC) List - Vehicle .

If DTC B101E is not set

3. Verify DTC B0997 is not set

If DTC B0997 is set

Replace the P17 Info Display Module.

If DTC B0997 is not set

4. All OK

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair. Refer to Radio Control Assembly Replacement

DTC B1024: CIRCUIT BOARD TEMPERATURE SENSOR ABOVE MAXIMUM THRESHOLD (AUDIO AMPLIFIER)

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Refer to Diagnostic Procedure Instructions to provide an overview of each diagnostic category.

DTC Descriptor

DTC B1024 11

Circuit Board Temperature Sensor Above Maximum Threshold

Circuit/System Description

The audio amplifier monitors the internal circuitry for excessive temperature. When the amplifier senses an internal circuitry temperature greater than 95°C (203°F), the amplifier will set DTC B1024 11 and shut down until the internal circuitry cools below 90°C (194°F). No external circuit diagnosis is involved.

Conditions for Running the DTC

Radio ON.

Battery voltage must be between 9-16 volts.

Conditions for Setting the DTC

The audio amplifier detects an over-heat condition greater than 95°C (203°F) of the internal amplifier circuitry.

Action Taken When the DTC Sets

The audio amplifier will shut down and all speakers will be inoperative.

Conditions for Clearing the DTC

The condition responsible for setting the DTC no longer exists.

A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

Diagnostic Aids

Extended use or extremely high volume especially in warm weather conditions may cause this DTC to set. Under these conditions it may be normal for this DTC to set to prevent permanent damage to the audio amplifier circuitry.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

NOTE: Allow the vehicle cabin to cool if the temperature inside the vehicle is excessive before proceeding with this diagnostic procedure.

1. Verify the DTC sets outside of the Conditions for Running and Setting. Since most occurrences of this DTC are caused by extreme vehicle cabin temperatures due to ambient conditions, review with the customer the conditions under which the DTC set.

If the DTC sets within the Conditions for Running and Setting.

The system is operating as designed, All OK.

If the DTC sets outside the Conditions for Running and Setting.

2. Using the scan tool, clear the DTC.

3. Verify the DTC does not set while operating the infotainment system under the conditions the customer

experienced the concern.

If the DTC sets

Replace the T3 Audio Amplifier

If the DTC does not set

4. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Refer to Control Module References for audio amplifier replacement, setup, and programming

DTC B1024: CIRCUIT BOARD TEMPERATURE SENSOR THRESHOLD

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Refer to Diagnostic Procedure Instructions to provide an overview of each diagnostic category.

DTC Descriptor

DTC B1024 53

Circuit Board Temperature Sensor Below Minimum Threshold

DTC B1024 54

Circuit Board Temperature Sensor Above Maximum Threshold

Circuit/System Description

The human machine interface control module monitors the internal circuitry for excessive temperature. When a temperature outside of the range is detected, the module sets the DTC and limits its operation to avoid damage.

Conditions for Running the DTC

Ignition On/Vehicle in Service Mode. The system voltage is 9-16 V

The test is run once per second when the infotainment system is operating

Conditions for Setting the DTC

B1024 53

The module senses an internal temperature less than -40°C (-40°F).

B1024 54

The module senses an internal temperature greater than 69°C (156°F).

Action Taken When the DTC Sets

The human machine interface control module sets the DTC.

A message is displayed indicating that the system performance is being impacted by the excessive temperature condition.

The module stops communicating on the MOST Bus network, but does not interrupt communication on the network.

The infotainment system and the Info Display Module will have limited or no functionality.

Components or other subsystems that interface with the infotainment system may have limited or no functionality.

Conditions for Clearing the DTC

The internal temperature is between -40°C (-40°F) and 69°C (156°F).

A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

Diagnostic Aids

Under certain conditions it may be normal for this DTC to set to prevent permanent damage to the module.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

NOTE: Allow the vehicle cabin to cool if the temperature inside the vehicle is excessive before proceeding with this diagnostic procedure.

1. Verify the DTC sets outside of the Conditions for Running and Setting. Since most occurrences of this DTC are caused by extreme vehicle cabin temperatures due to ambient conditions, review with the customer the conditions under which the DTC set.

If the DTC sets within the Conditions for Running and Setting.

The system is operating as designed, All OK.

If the DTC sets outside the Conditions for Running and Setting.

2. Using the scan tool, clear the DTC.

3. Verify the DTC does not set while operating the infotainment system under the conditions the customer experienced the concern.

If the DTC sets

Replace the K74 Human Machine Interface Control Module

If the DTC does not set

4. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Control Module References for human machine interface control module replacement, programming, and setup.

DTC B1025-B1135: AUDIO OUTPUT CIRCUITS

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Refer to Diagnostic Procedure Instructions to provide an overview of each diagnostic category.

DTC Descriptors

DTC B1025

Audio Output 1 Circuit

DTC B1035

Audio Output 2 Circuit

DTC B1045

Audio Output 3 Circuit

DTC B1065

Audio Output 5 Circuit

DTC B1075

Audio Output 6 Circuit

DTC B1085

Audio Output 7 Circuit

For symptom byte information refer to Symptom Byte List .

Diagnostic Fault Information

Circuit/System Description

The Media Oriented Systems Transport (MOST) is a high-speed multimedia network technology. The serial MOST bus uses a ring topology and synchronous data communication to transmit audio, video, data and control information between any devices attached.

The audio amplifier is a participant on the MOST network. The audio amplifier receives audio inputs and control information from the MOST bus.

Each of the audio output channel circuits (+) and (-), at the audio amplifier have a DC bias voltage that is approximately one half of the battery voltage. When using a DMM, each of the audio output channel circuits will measure approximately 6.5V DC. The audio being played on the system is produced by a varying AC voltage that is centered around the DC bias voltage on the same circuit. The AC voltage is what causes the speaker cone to move and produce sound.

Diagnostic Aids

Improper speaker mounting or loose trim may cause an audible buzz or distortion. Inspect the appropriate speaker and the surrounding interior trim for proper and secure mounting.

The EL-50334-6 Audio System Diagnostic CD contains audio tracks that can be used to duplicate and isolate such concerns. Tracks 11 and 12 contain audio sweep tones for testing for speaker and grill rattles.

If the speaker or surrounding interior trim is found to be loose or improperly secured, correctly secure the item.

The test tones on the CD may be copied to a USB drive or other device to use during testing.

Some audio output circuits are connected to more than one speaker, dependant on vehicle equipment. It may be necessary to disconnect one or more speakers during testing of some circuits.

Conditions for Running the DTC

NOTE: DTC B1325 must not be set as current for the amplifier to run any of the following tests.

DTC B1025 01, B1035 01, B1045 01, B1065 01, B1075 01, B1085 01

The test is run initially upon amplifier wake-up, and periodically every one second after amplifier operation begins.

DTC B1025 02, B1035 02, B1045 02, B1065 02, B1075 02, B1085 02

The test is run initially upon amplifier wake-up, and periodically every one second after amplifier operation begins.

DTC B1025 04, B1035 04, B1045 04, B1065 04, B1075 04, B1085 04

The test is run once during amplifier wake-up.

Conditions for Setting the DTC

DTC B1025 01, B1035 01, B1045 01, B1065 01, B1075 01, B1085 01

A short to voltage is detected on the specified (+) or (-) signal circuit

DTC B1025 02, B1035 02, B1045 02, B1065 02, B1075 02, B1085 02

A short to ground is detected on the specified (+) or (-) signal circuit

DTC B1025 04, B1035 04, B1045 04, B1065 04, B1075 04, B1085 04

An open is detected on the specified (+) or (-) signal circuit

Action Taken When the DTC Sets

The amplifier mutes the output channel and no sound is present from the speaker(s) that have a current circuit fault.

Conditions for Clearing the DTC

The condition for setting the DTC is no longer present.

A history DTC will clear once 50 consecutive malfunction-free ignition cycles have occurred.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information Special Tools

EL-50334-50 USB Cable and Adapter Kit

Circuit/System Verification

1. Ignition ON, infotainment system ON, mute OFF.

2. Verify clear audio is heard from each speaker, adjusting fade and balance controls to test each speaker individually.

If audio is inoperative from one or more speakers, or the audio emitted is not clear

Refer to Circuit/System Testing.

If clear audio is heard from all speakers

3. All OK.

Circuit/System Testing

NOTE: Some circuits supply audio signals to more than one speaker. It may be necessary to disconnect all speakers on the affected audio circuit when performing circuit tests.

1. Ignition OFF, disconnect the harness connector at the appropriate P19 Speaker. Ignition ON, infotainment system ON, mute OFF.

2. Test for 5 - 7 V between the appropriate signal circuit terminals listed below and ground. Front door, tweeter, rear door and subwoofer speakers audio (-) circuit terminal 1 Front door, tweeter, rear door and subwoofer speakers audio (+) circuit terminal 2 If less than 5 V

1. Ignition OFF, disconnect the X1 and X2 harness connectors at the T3 Audio Amplifier.

2. Test for infinite resistance between the signal circuit and ground.

If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance

3. Test for less than 2 Ω in the signal circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit. If less than 2 Ω, replace the T3 Audio Amplifier.

If greater than 7 V

1. Ignition OFF, disconnect the X1 and X2 harness connectors at the T3 Audio Amplifier. Ignition ON.

2. Test for less than 1 V between the signal circuit and ground.

If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V, replace the T3 Audio Amplifier.

If 5 - 7 V

3. Test or replace the P19 Speaker.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Speaker Replacement Reference

Refer to Control Module References for audio amplifier replacement, programming, and setup.

DTC B124B: USB 1 CIRCUIT

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Refer to Diagnostic Procedure Instructions to provide an overview of each diagnostic category.

DTC Descriptor

DTC B124B

USB 1 Circuit

For symptom byte information refer to Symptom Byte List .

Diagnostic Fault Information

Circuit/System Description

The infotainment system has a USB port and a Auxiliary Audio Input Jack located in the center console. The receptacle assembly receives fused battery voltage and ground from the harness to power the internal hub device as well as providing additional amperage to power USB devices.

The internal hub device interfaces directly with the human machine interface control module via a standard USB cable. A Mini type USB connector is used to connect the human machine interface control module and the USB receptacle. Standard USB male to female connections are typically used for connecting USB cables together where an in-line connection is required. An in-line cable connection is typically found between the console and I/P harness.

Auxiliary Audio Input Jack

When a portable audio playback device is connected to the 3.5 mm (1/8 in.) auxiliary audio input jack an internal switch opens the detection signal circuit within the hub. The HMI detects the device and AUX becomes available as an audio source. Audio signals from the device are converted from analog to digital, these signals are then sent to the HMI from the auxiliary input jack via USB.

USB Port

The USB port allows connectivity to the infotainment system from portable media players or a USB storage device (memory stick/flash drive). When a device is connected to the USB port, the system detects the device and switches to USB as the audio source. Once connected, the device can be controlled from the radio controls.

Not all portable media player devices or file types are compatible. Refer to the owner's manual for information on USB devices, control, and operation.

Conditions for Running the DTC

Ignition On/Vehicle in Service Mode. The system voltage is 9-16 V

The infotainment system is ON

The test is run once per second when the infotainment system is operating

Conditions for Setting the DTC

B124B 0B

The human machine interface control module detects an excessive current condition on the USB 5 V circuit.

B124B 04

The human machine interface control module does not detect the vehicle hub device.

B124B 11

The human machine interface control module detects an additional hub device attached to the vehicle USB port.

Action Taken When the DTC Sets

The USB port is inoperative while the DTC is current.

Conditions for Clearing the DTC

The condition for setting the DTC is no longer present.

A history DTC will clear once 50 consecutive malfunction-free ignition cycles have occurred.

Diagnostic Aids

This DTC may be set due to the connection of an incompatible or faulty USB device.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information Special Tools

EL-50334-20 Multi-Media Interface Tester (MIT)

EL-50334-50 USB Cable and Adapter Kit

EL-50334-14 Infotainment Test Cable

Circuit/System Verification

1. Verify DTC B124B is not set. Since occurrences of this DTC can be caused by an incompatible or faulty USB device, review with the customer the conditions under which their concern occurred.

If DTC B124B is set.

Refer to Circuit/System Testing.

If DTC B124B is not set.

2. Ignition On/Vehicle in Service Mode. Infotainment system ON.

3. Connect the EL-50334-20 Multi-Media Interface Tester (MIT) to the X83 Auxiliary Audio Input USB port and select the USB test mode.

4. Verify the audio from the EL-50334-20 Multi-Media Interface Tester (MIT) is heard through the infotainment system while operating the system to play audio from the test tool.

If audio is not heard from the test tool

Refer to Circuit/System Testing

If audio is heard from test tool

5. Verify the infotainment system can be switched to AUX as the audio source with the EL-50334-20 Multi- Media Interface Tester (MIT) connected to the auxiliary audio input jack.

If the infotainment system can not be switched to AUX as the audio source

Refer to Circuit/System Testing

If the infotainment system can be switched to AUX as the audio source

6. Verify the audio from the EL-50334-20 Multi-Media Interface Tester (MIT) is heard through the vehicle infotainment system while operating the test tool to begin audio playback.

If audio is not heard from the test tool.

Refer to Circuit/System Testing

If audio is heard from the test tool.

7. All OK

Circuit/System Testing

1. Ignition OFF, disconnect the X1 harness connector at the X83 Auxiliary Audio Input.

2. Test for less than 10 Ω between the ground circuit terminal 4 and ground.

If 10 Ω or greater

1. Ignition OFF.

2. Test for less than 2 Ω in the ground circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit.

If less than 2 Ω, repair the open/high resistance in the ground connection.

If less than 10 Ω

3. Verify that a test lamp illuminates between the B+ circuit terminal 6 and ground.

If the test lamp does not illuminate

1. Ignition OFF, remove the test lamp.

2. Test for less than 2 Ω in the B+ circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit.

If the test lamp illuminates

4. Verify the USB cable is properly connected at all components and in-line connections, and there is no damage to the cable or connections.

If connection problems or cable damage is noted.

Perform the appropriate repair or replacement to correct any issues.

If no connection problems or cable damage is noted.

5. Connect the X1 harness connector at the X83 Auxiliary Audio Input.

6. Disconnect the vehicle USB cable X3 harness connector at the K74 Human Machine Interface Control Module and the X83 Auxiliary Audio Input Adapter.

7. Connect the EL-50334-14 Infotainment Test Cable and the EL-50334-2 Type-A Female to Mini-B Male Cable together. Connect the assembled test cable to the K74 Human Machine Interface Control Module and the X83 Auxiliary Audio Input.

8. Ignition On/Vehicle in Service Mode. Infotainment system ON.

9. Connect the EL-50334-20 Multi-Media Interface Tester (MIT) to the X83 Auxiliary Audio Input USB port and select the USB test mode.

10. Verify the audio from the EL-50334-20 Multi-Media Interface Tester (MIT) is heard through the infotainment system while operating the system to play audio from the test tool.

If audio is not heard from the test tool

1. Replace the X83 Auxiliary Audio Input Adapter. Connect all harness connectors.

2. Connect the EL-50334-20 Multi-Media Interface Tester (MIT) to the X83 Auxiliary Audio Input USB port and select the USB test mode.

3. Verify the audio from the EL-50334-20 Multi-Media Interface Tester (MIT) is heard through the infotainment system while operating the system to play audio from the test tool.

If audio is not heard from the test tool, replace the K74 Human Machine Interface Control

Module.

If audio is heard from the test tool

11. Connect the EL-50334-20 Multi-Media Interface Tester (MIT) to the X83 Auxiliary Audio Input AUX port and select the AUX test mode.

12. Verify the audio from the EL-50334-20 Multi-Media Interface Tester (MIT) is heard through the infotainment system while operating the system to play audio from the test tool.

If audio is not heard from the test tool

1. Replace the X83 Auxiliary Audio Input Adapter. Connect all harness connectors.

If audio is heard from the test tool.

13. Replace the vehicle USB cable between the K74 Human Machine Interface Control Module and the X83 Auxiliary Audio Input Adapter.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair. Refer to Audio Disc Player and USB Receptacle Replacement

Refer to Control Module References for human machine interface control module replacement, programming, and setup.

DTC B124F: UNIVERSAL SERIAL BUS (USB) PROGRAMMING

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Refer to Diagnostic Procedure Instructions to provide an overview of each diagnostic category.

DTC Descriptor

DTC B124F

Universal Serial Bus (USB) Programming

For symptom byte information, refer to Symptom Byte List .

Circuit/System Description

Certain devices in the entertainment system must be programmed with specific software and other information to operate correctly. This DTC is the result of an unsuccessful USB programming event of the device. The symptom byte information is for engineering reference only. No external circuit diagnosis is involved

Conditions for Running the DTC

Once upon each USB Programming Event.

Conditions for Setting the DTC

The programming event was incomplete, or completed with errors.

Action Taken When the DTC Sets

The entertainment system has limited or no functionality.

Conditions for Clearing the DTC

The programming event completes successfully.

Circuit/System Verification

1. Vehicle in Service Mode.

2. Verify DTC B124F is not set.

If DTC B124F is set

1. Program the device that set the DTC.

2. Verify the DTC does not set.

If DTC is set, replace the device that set the DTC. If the DTC is not set

3. All OK.

If DTC B124F is not set

3. All OK

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Control Module References for device replacement, programming, and setup.

DTC B125A: ANTENNA SIGNAL CIRCUIT

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Refer to Diagnostic Procedure Instructions to provide an overview of each diagnostic category.

DTC Descriptors

DTC B125A 02

Antenna Signal Circuit Short to Ground

DTC B125A 04

Antenna Signal Circuit Open Circuit

DTC B125A 01

Antenna Signal Circuit Short to Battery

Diagnostic Fault Information

Circuit/System Description

The radio antenna for AM and FM radio reception is connected to the radio with a coaxial cable.

Conditions for Running the DTC

Ignition ON/Vehicle in Service Mode.

Battery voltage must be between 9 - 16 V.

Conditions for Setting the DTC

B125A 02

The radio detects a short to ground in the antenna signal circuit center conductor.

B125A 04

The radio detects an open in the antenna signal circuit center conductor.

B125A 01

The radio detects a short to battery in the antenna signal circuit center conductor.

Action Taken When the DTC Sets

Radio reception may be poor or not available.

Conditions for Clearing the DTC

The condition responsible for setting the DTC no longer exists.

A history DTC will clears after 50 consecutive malfunction-free ignition cycles have occurred.

Diagnostic Aids

Poor AM and FM radio reception is dependent on multiple influences, some of which may not be vehicle related. Areas which have high RF traffic or block the signal path may cause a degradation in radio reception. Radio reception may also be influenced by items within the vehicle, but are not part of the radio system. Such examples are aftermarket electrical accessories or other items which may generate noise in the vehicle electrical system.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Inspect the antenna for proper mounting or physical damage.

If damage is found

Repair or replace as necessary

If no damage is found

2. Ignition ON/Vehicle in Service Mode, A11 Radio ON.

3. Verify station reception is normal when tuned to several known good AM and FM stations.

If AM or FM reception is poor.

Refer to Circuit/System Testing

If reception is normal

4. All OK.

Circuit/System Testing

1. Ignition OFF/Vehicle OFF, disconnect the radio antenna coax cable from the A11 Radio and from the T2RR Antenna - Roof Rear.

2. Verify the antenna coax cable passes the coax cable component test. Refer to Component Testing.

If the coax cable does not pass the test

Replace the antenna coax cable

If the coax cable passes the test

3. Connect the antenna coax cable to the T2RR Antenna - Roof Rear.

4. Test for infinite resistance between the coax cable center terminal and the coax cable outer shield at the radio end of the coax cable.

If less than infinite resistance

Replace the radio antenna base.

If infinite resistance

5. Test for less than 10 Ω between the coax cable outer shield and ground at the radio end of the coax cable.

If 10 Ω or greater

1. Clean the mounting surface of the radio antenna base.

2. Connect the antenna coax cable to the T2RR Antenna - Roof Rear.

3. Test for less than 10 Ω between the coax cable outer shield and ground at the radio end of the coax cable.

If 10 Ω or greater, replace the antenna base.

If less than 10 Ω, connect all harness connectors. Verify station reception is normal when tuned to several known good AM and FM stations. If AM or FM reception concerns are still present, replace the A11 Radio.

If less than 10 Ω

6. Test or replace the A11 Radio.

Component Testing

CAUTION: Refer to Test Probe Caution .

NOTE: Before testing the coax cable, check the cable exterior for being pinched, cut, damaged, or having loose connections at the components, which can cause reception issues.

To prevent false reading when testing the center coax terminals, use care not to ground the test probe on the outer housing/shield.

Coax Cable Test

1. Ignition OFF/Vehicle OFF, disconnect the coax cable at both components.

2. Test for less than 5 Ω between coax cable center terminal end to end.

If 5 Ω or greater

Replace the coax cable

If less than 5 Ω

3. Test for less than 5 Ω between the coax cable outer shield end to end.

If 5 Ω or greater

Replace the coax cable

If less than 5 Ω

4. Test for infinite resistance between the coax cable center terminal and the coax cable outer shield.

If less than infinite resistance

Replace the coax cable

If infinite resistance

5. All OK

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Refer to High Frequency Antenna Replacement

Refer to Control Module References for radio replacement, programming, and setup.

DTC B125C: SATELLITE ANTENNA CIRCUIT

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Refer to Diagnostic Procedure Instructions to provide an overview of each diagnostic category.

DTC Descriptors

DTC B125C 01

Satellite Antenna Circuit Short to Battery

DTC B125C 02

Satellite Antenna Circuit Short to Ground

DTC B125C 04

Satellite Antenna Circuit Open

Circuit/System Description

The digital radio receiver, located inside the radio, receives digital radio information from the digital radio antenna located on the outside of the vehicle. The digital radio receiver is connected to the digital radio antenna via a shielded coax cable. The digital radio antenna contains an amplifier which is powered by the radio through the coax cable.

Conditions for Running the DTC

This DTC is run every 300 milliseconds.

Conditions for Setting the DTC

The radio detects a circuit fault in the digital radio antenna.

Action Taken When the DTC Sets

The radio displays No XM Signal or Check Antenna.

Conditions for Clearing the DTC

A current DTC clears when the condition for setting the DTC is no longer present. A history DTC clears after 100 malfunction-free ignition cycles.

Diagnostic Aids

The digital radio antenna requires a clear line of sight to the sky to operate properly. Reception may be limited, intermittent, or unavailable inside structures.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

Special Tools

EL-48028 Digital Radio Test Antenna

Circuit/System Verification

1. With the vehicle outside in an area with an unobstructed view of the southern sky, tune to XM.

2. Verify DTC B125C is not set as current and the No XM Signal message is not displayed on the radio.

If DTC B125C is set as current or the No XM Signal message is displayed.

Refer to Circuit/System Testing.

If DTC B125C is not set as current and the No XM Signal message is not displayed.

3. All OK.

Circuit/System Testing

1. Ignition OFF/Vehicle OFF, disconnect the digital radio antenna coax cable from the A11 Radio. Connect the

EL-48028 Digital Radio Test Antenna to the radio and place on the roof of the vehicle.

2. Ignition ON/Vehicle in Service Mode, radio tuned to XM channel 1.

3. Verify DTC B125C is not set as current and XM reception is improved.

If DTC B125C is set as current or XM reception is not improved

Replace the A11 Radio.

If DTC B125C is not set as current and XM reception is improved

4. Ignition OFF/Vehicle OFF, disconnect the digital radio antenna coax cable from the T2RR Antenna - Roof Rear.

5. Verify the digital radio antenna coax cable passes the coax cable component test. Refer to Component Testing.

If the coax cable does not pass the test

Replace the antenna coax cable

If the coax cable passes the test

6. Test or replace the T2RR Antenna - Roof Rear.

Component Testing

CAUTION: Refer to Test Probe Caution .

NOTE: Before testing the coax cable, check the cable exterior for being pinched, cut, damaged, or having loose connections at the components, which can cause reception issues.

To prevent false reading when testing the center coax terminals, use care not to ground the test probe on the outer housing/shield.

Coax Cable Test

1. Ignition OFF/Vehicle OFF, disconnect the coax cable at both components.

2. Test for less than 5 Ω between coax cable center terminal end to end.

If 5 Ω or greater

Replace the coax cable

If less than 5 Ω

3. Test for less than 5 Ω between the coax cable outer shield end to end.

If 5 Ω or greater

Replace the coax cable

If less than 5 Ω

4. Test for infinite resistance between the coax cable center terminal and the coax cable outer shield.

If less than infinite resistance

Replace the coax cable

If infinite resistance

5. All OK

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to High Frequency Antenna Replacement

Refer to Control Module References for radio replacement, programming, and setup.

DTC B1271: THEFT PROTECTION ACTIVE

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Refer to Diagnostic Procedure Instructions to provide an overview of each diagnostic category.

DTC Descriptor

DTC B1271 00

Theft Protection Active

Circuit/System Description

When the radio is initially installed in the vehicle, the radio receives VIN information via serial data. The radio stores a portion of the VIN and compares this sequence to the VIN information received each time the radio powers on. The VIN in the radio is a single one-time learn.

The radio theft deterrent system is intended to disable or limit radio functionality if incorrect vehicle information is received by the radio. The radio disables functionality if the VIN information received by the radio does not match the VIN information that has been learned by the radio. This DTC is generated by the module when the Theft Protection is activated.

Conditions for Running the DTC

This DTC test runs when the radio changes from OFF to ON.

Conditions for Setting the DTC

The radio has learned a correct VIN sequence and the VIN information received via serial data does NOT match the learned VIN sequence.

Action Taken When the DTC Sets

The radio may be disabled or have limited functionality. The radio display will indicate that theft protection is active.

Conditions for Clearing the DTC

The radio receives the correct VIN information via serial data.

Diagnostic Aids

A possible cause of incorrect VIN info could be the radio was originally installed in another vehicle.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Vehicle in Service Mode, radio ON.

2. Verify DTC B1271 is not set.

If DTC B1271 is set

Replace the A11 Radio.

If DTC B1271 is not set

3. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Control Module References for radio replacement, programming, and setup.

DTC B127E: FRONT VIDEO DISPLAY OUTPUT SIGNAL

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Refer to Diagnostic Procedure Instructions to provide an overview of each diagnostic category.

DTC Descriptor

DTC B127E 00

Front Video Display Output Signal

Circuit/System Description

The infotainment display and controls are a separate component from the radio, combined into an assembly. The assembly is supplied battery voltage and ground from the vehicle harness. The human machine interface control module communicates digital video data for on-screen display through a dedicated cable containing the LVDS data circuits.

Control information, touch communications and dimming level for the display are communicated via a LIN serial data circuit to the human machine interface control module.

If the human machine interface control module detects the display is not responding to the output on the LVDS circuits, the human machine interface control module sets the DTC.

Conditions for Running the DTC

Ignition is ON or in the ACC position The system voltage is 9-16 V

The infotainment system is ON

The test is continuously when the infotainment system is operating

Conditions for Setting the DTC

The human machine interface control module detects the display is not responding to the output on the LVDS circuits.

Action Taken When the DTC Sets

The human machine interface control module sets this DTC No images are shown on the Info Display Module

Conditions for Clearing the DTC

The human machine interface control module detects a properly synced digital video signal.

A history DTC will clear once 50 consecutive malfunction-free ignition cycles have occurred.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information Special Tools

EL-50334-2 Type A female to Mini B male USB Cable EL-50334-14 Infotainment Test Cable

Circuit/System Testing

1. Vehicle OFF/Ignition OFF.

2. Verify the LVDS interface cable is properly connected at the P17 Info Display Module and the K74 Human Machine Interface Control Module connections and there is no damage to the cable or connections.

3. Ignition ON/Vehicle in Service Mode, infotainment system ON.

4. Verify the P17 Info Display Module does not display an image.

If the P17 Info Display Module displays an image.

All OK.

If the P17 Info Display Module does not display an image.

5. Vehicle OFF/Ignition OFF.

6. Disconnect the LVDS interface cable from the P17 Info Display Module.

7. Connect the EL-50334-2 Type A female to Mini B male USB Cable to the P17 Info Display Module. Connect the EL-50334-14 Infotainment Test Cable to the adapter.

8. Disconnect the LVDS interface cable from the K74 Human Machine Interface Control Module. Connect the EL-50334-14 Infotainment Test cable to the K74 Human Machine Interface Module.

9. Ignition ON/Vehicle in Service Mode, infotainment system ON.

10. Verify the P17 Info Display Module displays an image.

If the P17 Info Display Module does not display an image

1. Replace the P17 Info Display Module. Connect all harness connectors.

2. Ignition ON/Vehicle in Service Mode, infotainment system ON.

3. Verify the P17 Info Display Module displays an image.

If the P17 Info Display Module still does not display an image, replace the K74 Human Machine Interface Control Module.

If the P17 Info Display Module displays an image.

4. All OK.

If the P17 Info Display Module displays an image.

11. Replace the vehicle LVDS interface cable from the P17 Info Display Module to the K74 Human Machine Interface Module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Radio Control Assembly Replacement

Refer to Control Module References for human machine interface control module replacement, programming, and setup.

DTC B12A8: OPTICAL MEDIA DRIVE THEFT LOCKED

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Refer to Diagnostic Procedure Instructions to provide an overview of each diagnostic category.

DTC Descriptor

DTC B12A8 00

Optical Media Drive Theft Locked

Circuit/System Description

When the Media Disc Player is initially installed in the vehicle, it receives VIN information via serial data. The Media Disc Player stores a portion of the VIN and compares this sequence to the VIN information received each time the Media Disc Player powers on. The VIN in the Media Disc Player is a single one-time learn.

The Media Disc Player theft deterrent system is intended to disable or limit Media Disc Player functionality if incorrect vehicle information is received by the Media Disc Player. The Media Disc Player disables functionality if the VIN information received by the Media Disc Player does not match the VIN information that has been learned by the Media Disc Player. This DTC is generated by the module when the Theft Protection is activated.

Conditions for Running the DTC

This test runs once per second while the Media Disc Player is being accessed.

Conditions for Setting the DTC

The Media Disc Player has learned a correct VIN sequence and the VIN information received via serial data does NOT match the learned VIN sequence.

Action Taken When the DTC Sets

The Media Disc Player may be disabled or have limited functionality.

Conditions for Clearing the DTC

The Media Disc Player receives the correct VIN information via serial data.

Diagnostic Aids

A possible cause of incorrect VIN information could be the Media Disc Player was originally installed in another vehicle.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Vehicle in Service Mode.

2. Verify DTC B12A8 is not set.

If DTC B12A8 is set

Replace the A33 Media Disc Player.

If DTC B12A8 is not set

3. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Control Module References for media disc player replacement, programming, and setup.

DTC B1446 OR B1447: BACKUP POWER SOURCE

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Refer to Diagnostic Procedure Instructions to provide an overview of each diagnostic category.

DTC Descriptors

DTC B1446

Replace Backup Power Source Below Minimum Threshold

DTC B1447

Backup Power Source Open Circuit

For symptom byte information refer to Symptom Byte List

Diagnostic Fault Information

Circuit/System Description

The backup power source provides voltage to the telematics communication interface control module, to be able to successfully place a call in the event of a main battery disconnect during a collision event.

Conditions for Running the DTC

B1446 03

Ignition On/Vehicle in Service Mode.

System voltage is between 9.5 and 15.5 V. DTC B1447 is not set.

B1447 04

Ignition On/Vehicle in Service Mode.

System voltage is between 9.5 and 15.5 V.

The above conditions are present for greater than 10 s.

Conditions for Setting the DTC

B1446 03

The telematics communication interface control module detects that the backup power source voltage has dropped below the minimum threshold value.

B1447 04

The telematics communication interface control module detects no voltage from the backup power source.

Action Taken When the DTC Sets

B1446 03

The OnStar® status LED turns red.

B1447 04

The OnStar® status LED turns red.

The telematics communication interface control module will be unable to place a call in the event of a main battery disconnect during a collision event.

Conditions for Clearing the DTC

A current DTC B1446 will clear when the telematics communication interface control module detects the voltage of the backup power source is above the minimum threshold value.

A current DTC B1447 will clear when the telematics communication interface control module detects voltage from the backup power source.

A history DTC clears after 50 malfunction-free ignition cycles.

Diagnostic Aids

Shorting the backup power source positive voltage circuit to the backup power source ground circuit or chassis ground will activate the internal circuit protection of the backup power source, rendering the backup power source inoperative.

DTC B1447 may set if the K73 Telematics Communication Interface Control Module has been incorrectly disconnected or serviced. When disconnecting the K73 Telematics Communication Interface Control Module, disconnect the harness connector X1 at the K73 Telematics Communication Interface Control Module prior to disconnecting any other harness connectors. This will ensure the backup power source is preserved when voltage is removed from the K73 Telematics Communication Interface Control Module.

Reference Information

Schematic Reference

OnStar/Telematics Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

OnStar Description and Operation

Electrical Information Reference

Testing for Intermittent Conditions and Poor Connections Circuit Testing

Wiring Repairs

Connector Repairs

Circuit/System Testing

1. Ignition OFF/Vehicle OFF and all vehicle systems OFF, disconnect the X1 harness connector at the K73 Telematics Communication Interface Control Module. It may take up to 2 minutes for all vehicle systems to power down.

2. Test for greater than 12.3 V between the B+ circuit terminal 14 and the low reference circuit terminal 13.

If 12.3 V or less

1. Disconnect the C3 Telematics Communication Interface Control Module Battery.

2. Test for infinite resistance between the circuits listed below and ground. B+ circuit terminal 14

Low reference circuit terminal 13.

If less than infinite resistance, repair the short to ground in the circuit. If infinite resistance.

3. Test for less than 2 Ω in the circuits end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit.

If less than 2 Ω, replace the C3 Telematics Communication Interface Control Module Battery.

If greater than 12.3 V

3. Replace the K73 Telematics Communication Interface Control Module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Communication Interface Module Battery Replacement

Refer to Control Module References for telematics communication interface control module replacement, programming and setup.

DTC B2455: CELLULAR PHONE MICROPHONE CIRCUIT

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Refer to Diagnostic Procedure Instructions to provide an overview of each diagnostic category.

DTC Descriptors

DTC B2455 02

Cellular Phone Microphone Circuit Short to Ground

DTC B2455 04

Cellular Phone Microphone Circuit Open

Diagnostic Fault Information

Circuit/System Description

The telematics communication interface control module provides the cellular phone microphone with a supplied voltage on the cellular phone microphone high signal circuit. When the microphone is in use, voice data from the user is sent back to the telematics communication interface control module on the microphone low signal circuit.

Conditions for Running the DTC

The Vehicle must be ON or in Service Mode.

The system voltage is at least 9.5 V and no more than 15.5 V. All the above conditions are present for greater than 10 s.

Conditions for Setting the DTC

B2455 02

The telematics communication interface control module detects a short to ground in the cellular phone microphone signal circuit for 10 s or greater.

B2455 04

The following conditions will set this DTC:

The telematics communication interface control module detects an open/high resistance in the cellular phone

microphone signal circuit for 10 s or greater.

The telematics communication interface control module detects an open/high resistance in the low signal circuit for 10 s or greater.

Action Taken When the DTC Sets

The OnStar® status LED turns red.

The telematics communication interface control module will not receive a signal from the cellular phone microphone.

Calls can be placed but the caller cannot be heard.

Conditions for Clearing the DTC

The condition responsible for setting the DTC no longer exists.

A history DTC will clear once 50 consecutive malfunction-free ignition cycles have occurred.

Reference Information

Schematic Reference

OnStar/Telematics Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

OnStar Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

1. Ignition OFF/Vehicle OFF, disconnect the harness connector at the B24 cellular phone microphone, Ignition ON/Vehicle in Service Mode.

2. Test for 8.0-10.5 V between the signal circuit terminal B and ground.

If less than 8.0 V

1. Ignition OFF/Vehicle OFF, disconnect the X2 harness connector at the K73 telematics communication interface control module.

2. Test for infinite resistance between the signal circuit and ground.

If less than infinite resistance, repair the short to ground in the circuit.

If infinite resistance

3. Test for less than 2 Ω in the signal circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit.

If less than 2 Ω, replace the vehicle K73 Telematics Communication Interface Control Module.

If greater than 10.5 V

1. Ignition OFF/Vehicle OFF, disconnect the X2 harness connector at the K73 telematics communication interface control module, Ignition ON/Vehicle in Service Mode.

2. Test for less than 1 V between the signal circuit and ground.

If 1 V or greater, repair the short to voltage on the circuit.

If less than 1 V, replace the K73 Telematics Communication Interface Control Module.

If between 9.5-10.5 V

3. Test for less than 1 V between the signal circuit terminal A and ground.

If greater than 1 V

1. Ignition OFF/Vehicle OFF, disconnect the X2 harness connector at the K73 telematics communication interface control module, Ignition ON/Vehicle in Service Mode.

2. Test for less than 1 V between the signal circuit and ground.

If 1 V or greater, repair the short to voltage in the circuit.

If less than 1 V, repair the K73 Telematics Communication Interface Control Module.

If less than 1 V

4. Test for greater than 8 V between the signal circuit terminal B and the signal circuit terminal A.

If less than 8 V

1. Ignition OFF/Vehicle OFF, disconnect the connector X2 at the K73 telematics communication interface control module.

2. Test for infinite resistance between the low signal circuit and ground.

If less than infinite resistance, repair the short to ground in the circuit. If infinite resistance

3. Test for less than 2 Ω in the signal circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit.

If less than 2 Ω, replace the vehicle K73 Telematics Communication Interface Control Module.

If greater than 8 V

5. Test or replace the B24 Cellular Phone Microphone.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Mobile Telephone Microphone Replacement

Refer to Control Module References for telematics communication interface control module replacement, programming and setup.

DTC B2462: GLOBAL POSITIONING SYSTEM

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Refer to Diagnostic Procedure Instructions to provide an overview of each diagnostic category.

DTC Descriptors

DTC B2462 02

Global Positioning System Short to Ground

DTC B2462 04

Global Positioning System Open

Circuit/System Description

The navigation antenna is connected to the Telematics Communication Interface Control Module. The module supplies 5 V to the antenna to power the internal amplifier through the center conductor of the antenna coax cable.

When the vehicle is equipped with the optional navigation system, a Navigation Antenna Signal Splitter is installed to distribute the navigation signal to both the Telematics Communication Interface Control Module and the Human Machine Interface Control Module. The Human Machine Interface Control Module supplies 5 V through the coax cable to power the Navigation Antenna Signal Splitter.

Conditions for Running the DTC

Radio On.

System voltage is greater than 9 V and less than 16 V.

The navigation system/telematics communication interface control module tests the GPS antenna every 10 s.

Conditions for Setting the DTC

B2462 02

The Telematics Communication Interface Control Module or Human Machine Interface Control Module detects a short to ground on the GPS antenna signal circuit.

B2462 04

The Telematics Communication Interface Control Module or Human Machine Interface Control Module detects a open/high resistance on the GPS antenna signal circuit.

Action Taken When the DTC Sets

The Telematics Communication Interface Control Module or Human Machine Interface Control Module uses the last reported position and the vehicle speed signal to calculate the vehicle position.

Route guidance may be inaccurate.

Turn by turn navigation may be inaccurate or inoperative.

Conditions for Clearing the DTC

The condition responsible for setting the DTC no longer exists.

A history DTC will clear once 50 consecutive malfunction - free ignition cycles have occurred.

Diagnostic Aids

The scan tool Telematics Communication Interface Control Module GPS signal parameter will display a Yes or No dependent upon whether or not the module sees an increment of the seconds transmitted by GPS signals to the Telematics Communication Interface Control Module. Upon entering this screen, the GPS signal title will initially display Yes, regardless of the presence of time increment, for at least 2 seconds, while the algorithm in the scan tool determines the status of the clock. If increment is found, Yes is continually displayed. If the clock remains static, No is displayed. The scan tool looks for increment every second, regardless of current display.

Inaccurate or aged GPS position concerns which are no longer present may have been due to the temporary loss of GPS signal reception by the vehicle. Conditions such as tunnels or parking structures will restrict the cellular phone and navigation antenna from a clear view of the satellites in the sky and may have caused this temporary data loss.

The GPS requires a clear line of sight to the sky to operate properly. In most cases the GPS will not have reception near tall buildings or inside structures.

Reference Information

Schematic Reference

OnStar/Telematics Schematics

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

OnStar Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information Special Tools

EL-49903 OnStar Antenna Diagnostic Tool Kit

Circuit/System Verification

NOTE: The following verification requires the vehicle to be outside with an unobstructed view of the southern sky. Allow 5 minutes after turning the ignition ON for the vehicle to acquire the GPS satellites signal.

1. Ignition ON/vehicle in Service Mode.

2. Verify that DTC B2462 is not set in the Telematics Communication Interface Control Module.

If DTC B2462 is set in the Telematics Communication Interface Control Module and the vehicle is not equipped with a navigation system

Refer to Circuit/System Testing Without Navigation System.

If DTC B2462 is set in the Telematics Communication Interface Control Module and the vehicle is equipped with a navigation system

Refer to Circuit/System Testing With Navigation System.

If DTC B2462 is not set in the Telematics Communication Interface Control Module

3. Verify an OnStar advisor can locate the vehicle after performing a blue button press.

If the advisor can not locate the vehicle and the vehicle is not equipped with a navigation system

Refer to Circuit/System Testing Without Navigation System

If the advisor can not locate the vehicle and the vehicle is equipped with a navigation system

Refer to Circuit/System Testing With Navigation System.

If the advisor can locate the vehicle

4. Verify DTC B2462 is not set in the Human Machine Interface Control Module.

If DTC B2462 is set in the Human Machine Interface Control Module

Refer to Circuit/System Testing With Navigation System - Step 9.

If DTC B2462 is not set in the Human Machine Interface Control Module

5. Verify that the NO GPS symbol/message is not displayed on the radio display.

If the NO GPS symbol/message is displayed

Refer to Circuit/System Testing With Navigation System - Step 9.

If the NO GPS symbol/message is not displayed

6. All OK.

Circuit/System Testing

without Navigation System

NOTE: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

1. Ignition OFF/vehicle OFF, disconnect the GPS and cellular coax cable connector at the K73 Telematics Communication Interface Control Module.

2. Attach both leads of the EL-49903-1 OnStar test antenna to the EL-49903-5 combiner. Using the EL-49903-6 coax cable attach the grey connector to the combiner and the brown connector to the K73 Telematics Communication Interface Control Module. Place the test antenna on the roof of the vehicle, ignition ON.

3. Verify DTC B2462 is not set or that the OnStar advisor can locate the vehicle.

If DTC B2462 is set or the advisor can not locate the vehicle

Replace the K73 Telematics Communication Interface Control Module.

If DTC B2462 is not set or the advisor can locate the vehicle

4. Test the coax cable between the K73 Telematics Communication Interface Control Module and the T2RR Antenna - Roof Rear. Refer to component testing.

If the coax cable does not pass the test

Replace the coax cable.

If the coax cable passes the test

5. Test or replace the T2RR Antenna - Roof Rear.

with Navigation System

NOTE: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

1. Ignition OFF/vehicle OFF, disconnect the T2RR Antenna - Roof Rear coax cable at the T15 Navigation Antenna Signal Splitter.

2. Attach both leads of the EL-49903-1 OnStar test antenna to the EL-49903-5 combiner. Using the EL-49903-7 coax cable attach one grey connector to the combiner and the other grey connector to the T15 Navigation Antenna Signal Splitter. Place the test antenna on the roof of the vehicle, ignition ON.

3. Verify DTC B2462 is not set or that the OnStar advisor can locate the vehicle.

If DTC B2462 is not set or the advisor can locate the vehicle

1. Test the coax cable between the T15 Navigation Antenna Signal Splitter and the T2RR Antenna - Roof Rear. Refer to Component Testing.

If the coax cable does not pass the test Replace the coax cable.

If the coax cable passes the test

2. Replace the T2RR Antenna - Roof Rear.

If DTC B2462 is set or if the advisor can not locate the vehicle

4. Ignition OFF/vehicle OFF, disconnect the GPS and cellular coax cable connector at the K73 Telematics Communication Interface Control Module.

5. Attach both leads of the EL-49903-1 OnStar test antenna to the EL-49903-5 combiner. Using the EL-49903-6 coax cable attach the grey connector to the combiner and the brown connector to the K73 Telematics Communication Interface Control Module. Place the test antenna on the roof of the vehicle, ignition ON.

6. Verify DTC B2462 is not set or that the OnStar advisor can locate the vehicle.

If DTC B2462 is set or the advisor can not locate the vehicle.

Replace the K73 Telematics Communication Interface Control Module.

If DTC B2462 is not set or the advisor can locate the vehicle.

7. Ignition OFF/vehicle OFF.

8. Test the coax cable between the T15 Navigation Antenna Signal Splitter and the K73 Telematics

Communication Interface Control Module. Refer to Component Testing.

If the coax cable does not pass the test.

Replace the coax cable.

If the coax cable passes the test.

9. Ignition OFF/vehicle OFF, disconnect the blue GPS coax cable connector at the K74 Human Machine Interface Control Module.

10. Attach the EL-49903-1 OnStar test antenna blue connector to the K74 Human Machine Interface Control Module and place the test antenna on the roof of the vehicle.

11. Ignition ON/vehicle in Service Mode.

12. Verify DTC B2462 is not set or that the NO GPS symbol/message is not displayed on the radio.

If DTC B2462 is set or the NO GPS symbol/message is displayed

Replace the K74 Human Machine Interface Control Module

If DTC B2462 is not set or if the NO GPS symbol/message is not displayed.

13. Ignition OFF/vehicle OFF.

14. Test the coax cable between the T15 Navigation Antenna Signal Splitter and the K74 Human Machine Interface Control Module. Refer to Component Testing.

If the coax cable does not pass the test.

Replace the coax cable.

If the coax cable passes the test.

15. Test or replace the T15 Navigation Antenna Signal Splitter.

Component Testing

CAUTION: Refer to Test Probe Caution .

NOTE: Before testing the coax cable, check the cable exterior for being pinched, cut, damaged, or having loose connections at the components, which can cause reception issues.

To prevent false reading when testing the center coax terminals, use care not to ground the test probe on the outer housing/shield.

The vehicle may be equipped with sectioned coax. Test each section and replace only the faulty section, not the entire length of coax.

Coax Cable Test

1. Ignition OFF/vehicle OFF, disconnect the coax cable at both components.

2. Test for less than 5 Ω between the coax cable center terminal end to end.

If 5 Ω or greater

Replace the coax cable.

If less than 5 Ω

3. Test for greater than 5 Ω between the coax cable outer shield end to end.

If 5 Ω or greater

Replace the coax cable.

If less than 5 Ω

4. Test for infinite resistance between the coax cable center terminal and the coax cable outer shield.

If less than infinite resistance

Replace the coax cable.

If infinite resistance

5. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to High Frequency Antenna Replacement

Refer to Control Module References for Human Machine Interface control module or Telematics Communication Interface Control Module replacement, programming, and setup.

DTC B2470: CELLULAR PHONE ANTENNA CIRCUIT MALFUNCTION

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Refer to Diagnostic Procedure Instructions to provide an overview of each diagnostic category.

DTC Descriptors

DTC B2470 02

Cellular Phone Antenna Circuit Malfunction Short to Ground

DTC B2470 04

Cellular Phone Antenna Circuit Malfunction Open Circuit

Circuit/System Description

The primary cellular phone antenna element is connected to the telematics communication interface control module (violet connector) via a shielded coaxial cable. Cellular communication takes place on both the primary cellular antenna signal circuit and the GPS/secondary cellular antenna signal circuit. This diagnostic only applies to the primary cellular antenna signal circuit. Internal to the antenna on the cellular antenna signal circuit resistance is used to apply a load, which the telematics communication interface control module uses to detect the presence of the antenna.

Conditions for Running the DTC

Ignition in the RUN or ACC position.

System voltage is between 9.5 V and 15.5 V.

The above conditions are present for greater than 1 s.

Conditions for Setting the DTC

B2470 02

The telematics communication interface control module detects a short to ground on the primary cellular antenna signal circuit.

B2470 04

The telematics communication interface control module detects an open or high resistance on the primary cellular antenna signal circuit.

The above conditions are present for greater than 1 s.

Action Taken When the DTC Sets

The OnStar® status LED turns red.

Conditions for Clearing the DTC

The telematics communication interface control module detects the presence of a cellular antenna. A history DTC clears after 50 malfunction-free ignition cycles.

Reference Information

Schematic Reference

OnStar/Telematics Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

OnStar Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information Special Tools

EL-49903-1 Test Antenna Navn-Cell Comn

Circuit/System Testing

NOTE: The vehicle may be equipped with sectioned coax. Test each section and replace only the faulty section, not the entire length of coax.

The following verification requires the vehicle to be outside with an unobstructed view of the southern sky. Allow 5 min after turning the ignition ON for the GPS satellites to acquire vehicle signal.

1. Ignition OFF/Vehicle OFF and all vehicle systems OFF, disconnect the violet primary cellular coax cable connector at the K73 Telematics Communication Interface Control Module. It may take up to 2 min for all vehicle systems to power down.

2. Using the EL-49903-1 Test Antenna Navn-Cell Comn connect the violet coax cable to the K73 Telematics Communication Interface Control Module. Place the test antenna on the roof of the vehicle, ignition ON/vehicle in Service Mode.

3. Verify the DTC does not set or a call can be completed to the OnStar Call Center while operating the vehicle within the conditions for running the DTC.

If the DTC sets or a call can not be completed to the OnStar Call Center

Replace the K73 Telematics Communications Interface Control Module.

If the DTC does not set or a call can be completed to the OnStar Call Center

4. Ignition OFF/Vehicle OFF.

5. Disconnect the EL-49903-1 Test Antenna Navn-Cell Comn from the K73 Telematics Communication Interface Control Module

6. Test the coax cable. Refer to Component Testing.

If the coax cable does not pass the test

Replace the coax cable.

If the coax cable passes the test

7. Test or replace the T2RR Antenna - Roof Rear.

Component Testing

CAUTION: Refer to Test Probe Caution

NOTE: Before testing the coax cable, check the cable exterior for being pinched, cut, damaged, or having loose connections at the components, which can cause reception issues.

To prevent false readings when testing the center coax terminals, use care not to ground the test probe on the outer housing/shield.

Coax Cable Test

1. Test for less than 5 Ω between the coax cable center terminal end to end.

If 5 Ω or greater

Replace the coax cable.

If less than 5 Ω

2. Test for greater than 5 Ω between the coax cable outer shield end to end.

If 5 Ω or greater

Replace the coax cable.

If less than 5 Ω

3. Test for infinite resistance between the coax cable center terminal and the coax cable outer shield.

If less than infinite resistance

Replace the coax cable.

If infinite resistance

4. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair procedure.

Refer to High Frequency Antenna Replacement

Refer to Control Module References for telematics communication interface control module replacement, setup, and programming

DTC B2476 OR B2482: CELLULAR PHONE SELECT SERVICE SWITCH

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Refer to Diagnostic Procedure Instructions to provide an overview of each diagnostic category.

DTC Descriptors

DTC B2476 04

Cellular Phone Select Service Switch Open

DTC B2476 59

Cellular Phone Select Service Switch Protection Time-out

DTC B2482 00

Cellular Phone Select Service Switch Range/Performance

Diagnostic Fault Information

Circuit/System Description

The OnStar® button assembly consists of 3 buttons: Call/Answer, OnStar® Call Center, and OnStar® Emergency. The telematics communication interface control module supplies the OnStar® button assembly with 10 V via the 10 V reference circuit. Each of the buttons, when pressed, completes the circuit across a resistor allowing a specific voltage to be returned to the telematics communication interface control module over the keypad signal circuit. Depending upon the voltage range returned, the telematics communication interface control module is able to identify which button has been pressed.

Conditions for Running the DTC

Vehicle in Service Mode/Ignition ON.

Battery voltage must be between 9 - 16 V.

Conditions for Setting the DTC

B2476 04

The telematics communication interface control module detects an open/high resistance on the keypad supply voltage circuit.

B2482 and B2476 59

The telematics communication interface control module detects a valid signal on the keypad signal circuit for longer than 15 s. If one of the OnStar® buttons is held or stuck for 15 s or greater, the telematics communication interface control module will set this DTC.

Action Taken When the DTC Sets

The OnStar® status LED turns red. No calls can be placed.

The telematics communication interface control module will ignore all inputs from the OnStar® button assembly.

Conditions for Clearing the DTC

The condition responsible for setting the DTC no longer exists.

A history DTC will clear once 50 consecutive malfunction-free ignition cycles have occurred.

Diagnostic Aids

After any repair is made to the 10 V reference circuit or button signal circuit the fuse to the telematics communication interface control module must be removed for 30 s to reset the control module. Failure to do so could result in incorrect diagnosis.

Reference Information

Schematic Reference

OnStar/Telematics Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

OnStar Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

NOTE: 10 V reference circuit measurement may vary with vehicle battery voltage.

Test for voltage range with vehicle battery measuring at a minimum of 11.5 V

1. Vehicle OFF/Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the S48B Multifunction Switch - Overhead Console. It may take up to 2 min for all vehicle systems to power down.

2. Test for less than 10 Ω between the ground circuit terminal 5 and ground.

If 10 Ω or greater

1. Vehicle OFF/Ignition OFF.

2. Test for less than 2 Ω in the ground circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit.

If less than 2 Ω, repair the open/high resistance in the ground connection.

If less than 10 Ω

3. Vehicle in Service Mode/Ignition ON.

4. Test for 8.0 - 10.5 V between the 10 V reference circuit terminal 16 and ground.

If less than 8.0 V

1. Vehicle OFF/Ignition OFF, disconnect the harness connector at the K73 Telematics Communication Interface Control Module.

2. Test for infinite resistance between the 10 V reference circuit and ground.

If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance

3. Test for less than 2 Ω in the 10 V reference circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit.

If less than 2 Ω, replace the K73 Telematics Communication Interface Control Module.

If greater than 10.5 V

1. Vehicle OFF/Ignition OFF, disconnect the harness connector at the K73 Telematics Communication Interface Control Module, vehicle in Service Mode/Ignition ON.

2. Test for less than 1 V between the 10 V reference circuit and ground. If 1 V or greater, repair the short to voltage on the circuit.

If less than 1 V, replace the K73 Telematics Communication Interface Control Module.

If between 8.0 - 10.5 V

5. Vehicle OFF/Ignition OFF.

6. Test for 500 - 900 Ω between the signal circuit terminal 17 and ground.

If less than 500 Ω

1. Disconnect the X1 harness connector at the K73 Telematics Communication Interface Control Module.

2. Test for infinite resistance between the signal circuit and ground.

If less than infinite resistance, repair the short to ground on the circuit.

If infinite resistance, replace the K73 Telematics Communication Interface Control Module.

If greater than 900 Ω

1. Disconnect the X1 harness connector at the K73 Telematics Communication Interface Control Module, vehicle in Service Mode/Ignition ON.

2. Test for less than 1 V between the signal circuit and ground.

If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V

3. Vehicle OFF.

4. Test for less than 2 Ω in the signal circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit.

If less than 2 Ω, replace the K73 Telematics Communication Interface Control Module.

If between 500 - 900 Ω

7. Test or replace the S48B Multifunction Switch - Overhead Console.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Roof Console Replacement

Refer to Control Module References for telematics communication interface control module replacement, programming and setup.

SYMPTOMS - CELLULAR COMMUNICATION

NOTE: The following steps must be completed before using the symptom table.

1. Perform the Diagnostic System Check - Vehicle before using the Symptom Tables in order to verify that all of the following are true:

There are no DTCs set.

The control modules can communicate via the serial data link.

2. Review the system operation in order to familiarize yourself with the system functions. Refer to OnStar Description and Operation.

Visual/Physical Inspection

Inspect for aftermarket devices which could affect the operation of the Radio/Audio System. Refer to

Checking Aftermarket Accessories .

Inspect for easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections .

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom:

Bluetooth Malfunction

No Global Positioning System (GPS) Reception OnStar Microphone Malfunction

OnStar Audio Malfunction

OnStar Button LED Malfunction

OnStar Call Center Remote Function Requests Malfunction OnStar Button Malfunction

Unable to Contact OnStar Call Center OnStar Voice Recognition Malfunction

OnStar Steering Wheel Control Functions Malfunction

SYMPTOMS - ENTERTAINMENT

IMPORTANT: The following steps must be completed before using the symptom table.

1. Perform the Diagnostic System Check - Vehicle before using the Symptom Tables in order to verify that all of the following are true:

There are no DTCs set.

The control modules can communicate via the serial data link.

2. Review the system operation in order to familiarize yourself with the system functions. Refer to Radio/Audio System Description and Operation.

Visual/Physical Inspection

Inspect for aftermarket devices which could affect the operation of the Radio/Audio System. Refer to

Checking Aftermarket Accessories .

Inspect for easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections .

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom:

Application Malfunction

Auxiliary Audio Input Malfunction Bluetooth Malfunction

Digital Radio Poor or No Reception

Navigation System - Voice Recognition Malfunction No Global Positioning System (GPS) Reception

Radio Poor Reception Speaker Malfunction

APPLICATION MALFUNCTION

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Refer to Diagnostic Procedure Instructions to provide an overview of each diagnostic category.

Circuit/System Description

The term application refers to any piece of software that works on a system (hardware) that is being operated by it's own software. Applications are typically small software programs which uses the hardware to perform a specific task, as opposed to operating the entire system.

Diagnostic Aids

For an application to be used, it must be installed on both the vehicle infotainment system and a compatible mobile device.

The application must work correctly on the device to work with the vehicle infotainment system.

The user may be required to log-in to the application on the mobile device before using the application from the vehicle controls.

Applications use the mobile device and connection to a service provider to operate. Connection quality issues, or service provider data transmission issues can give the appearance of a vehicle malfunction.

The device must be connected to the system. this may be done wirelessly via Bluetooth®, or via the vehicle USB port.

When a mobile device is connected via Bluetooth®, some or all of the device controls may be unavailable from the radio controls. This varies dependant upon the device being used. Refer to the vehicle owners manual, supplements, and the device manufacturers information for information on devices, control, and operation.

Refer to the device manufacturers information for the preferred connection method.

The device must be unlocked, and any additional applications should be closed.

If the device has any sound enhancement features such as noise reduction or echo control, these features should be turned off.

A low battery condition in the mobile device may not allow the device to connect to the system, or can create communication issues with the device. Verify the device battery state of charge and re-charge or replace as needed.

If a 'Please See Device' or similar type error message is displayed, this may indicate the device has lost it's connection to the vehicle, or the device has lost it's external data connection.

If a cable is used for connection, attempt to connect the device using a different cable; cables can deteriorate over time or become damaged.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Verify the application is installed on the mobile device and is up to date.

If the application is not installed or is not up to date.

Install or update the application on the device.

If the application is installed on the mobile device and is up to date

2. Verify the application operates correctly on the mobile device.

If the application is not operating correctly on the mobile device.

Refer to the application website

If the application is operating correctly on the mobile device.

3. Verify the radio calibrations are current.

If the radio calibrations are not current

Reprogram the radio and re-evaluate the concern.

If no update calibrations are available

4. Verify the application is installed on the radio and is up to date.

If the application is not installed or is not up to date.

Install or update the application on the radio.

If the application is installed on the radio and is up to date

5. Vehicle in Service Mode, radio ON, connect the mobile device to the infotainment system. Refer to the owners manual for information on the preferred connection method for the device.

If the mobile device cannot connect to the vehicle infotainment system.

If unable to connect via Bluetooth, refer to Bluetooth Malfunction .

If unable to connect via USB, refer to Auxiliary Audio Input Malfunction. If the mobile device connects to the vehicle infotainment system.

6. Launch the application.

7. Verify the applications operates properly with the vehicle infotainment system.

If the application does not function properly

Refer to diagnostic aids.

If the application functions properly

8. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Refer to Control Module References for radio replacement, setup, and programming AUXILIARY AUDIO INPUT MALFUNCTION

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Refer to Diagnostic Procedure Instructions to provide an overview of each diagnostic category.

DTC Descriptor

DTC B124B

USB 1 Circuit

For symptom byte information refer to Symptom Byte List .

Diagnostic Fault Information

Circuit/System Description

The infotainment system has a USB port and a Auxiliary Audio Input Jack located in the center console. The receptacle assembly receives fused battery voltage and ground from the harness to power the internal hub device as well as providing additional amperage to power USB devices.

The internal hub device interfaces directly with the human machine interface control module via a standard USB cable. A Mini type USB connector is used to connect the human machine interface control module and the USB receptacle. Standard USB male to female connections are typically used for connecting USB cables together where an in-line connection is required. An in-line cable connection is typically found between the console and I/P harness.

Auxiliary Audio Input Jack

When a portable audio playback device is connected to the 3.5 mm (1/8 in.) auxiliary audio input jack an internal switch opens the detection signal circuit within the hub. The HMI detects the device and AUX becomes available as an audio source. Audio signals from the device are converted from analog to digital, these signals are then sent to the HMI from the auxiliary input jack via USB.

USB Port

The USB port allows connectivity to the infotainment system from portable media players or a USB storage device (memory stick/flash drive). When a device is connected to the USB port, the system detects the device and switches to USB as the audio source. Once connected, the device can be controlled from the radio controls.

Not all portable media player devices or file types are compatible. Refer to the owner's manual for information on USB devices, control, and operation.

Conditions for Running the DTC

Ignition On/Vehicle in Service Mode. The system voltage is 9-16 V

The infotainment system is ON

The test is run once per second when the infotainment system is operating

Conditions for Setting the DTC

B124B 0B

The human machine interface control module detects an excessive current condition on the USB 5 V circuit.

B124B 04

The human machine interface control module does not detect the vehicle hub device.

B124B 11

The human machine interface control module detects an additional hub device attached to the vehicle USB port.

Action Taken When the DTC Sets

The USB port is inoperative while the DTC is current.

Conditions for Clearing the DTC

The condition for setting the DTC is no longer present.

A history DTC will clear once 50 consecutive malfunction-free ignition cycles have occurred.

Diagnostic Aids

This DTC may be set due to the connection of an incompatible or faulty USB device.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information Special Tools

EL-50334-20 Multi-Media Interface Tester (MIT)

EL-50334-50 USB Cable and Adapter Kit

EL-50334-14 Infotainment Test Cable

Circuit/System Verification

1. Verify DTC B124B is not set. Since occurrences of this DTC can be caused by an incompatible or faulty USB device, review with the customer the conditions under which their concern occurred.

If DTC B124B is set.

Refer to Circuit/System Testing.

If DTC B124B is not set.

2. Ignition On/Vehicle in Service Mode. Infotainment system ON.

3. Connect the EL-50334-20 Multi-Media Interface Tester (MIT) to the X83 Auxiliary Audio Input USB port and select the USB test mode.

4. Verify the audio from the EL-50334-20 Multi-Media Interface Tester (MIT) is heard through the infotainment system while operating the system to play audio from the test tool.

If audio is not heard from the test tool

Refer to Circuit/System Testing

If audio is heard from test tool

5. Verify the infotainment system can be switched to AUX as the audio source with the EL-50334-20 Multi- Media Interface Tester (MIT) connected to the auxiliary audio input jack.

If the infotainment system can not be switched to AUX as the audio source

Refer to Circuit/System Testing

If the infotainment system can be switched to AUX as the audio source

6. Verify the audio from the EL-50334-20 Multi-Media Interface Tester (MIT) is heard through the vehicle infotainment system while operating the test tool to begin audio playback.

If audio is not heard from the test tool.

Refer to Circuit/System Testing

If audio is heard from the test tool.

7. All OK

Circuit/System Testing

1. Ignition OFF, disconnect the X1 harness connector at the X83 Auxiliary Audio Input.

2. Test for less than 10 Ω between the ground circuit terminal 4 and ground.

If 10 Ω or greater

1. Ignition OFF.

2. Test for less than 2 Ω in the ground circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit.

If less than 2 Ω, repair the open/high resistance in the ground connection.

If less than 10 Ω

3. Verify that a test lamp illuminates between the B+ circuit terminal 6 and ground.

If the test lamp does not illuminate

1. Ignition OFF, remove the test lamp.

2. Test for less than 2 Ω in the B+ circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit.

If the test lamp illuminates

4. Verify the USB cable is properly connected at all components and in-line connections, and there is no damage to the cable or connections.

If connection problems or cable damage is noted.

Perform the appropriate repair or replacement to correct any issues.

If no connection problems or cable damage is noted.

5. Connect the X1 harness connector at the X83 Auxiliary Audio Input.

6. Disconnect the vehicle USB cable X3 harness connector at the K74 Human Machine Interface Control Module and the X83 Auxiliary Audio Input Adapter.

7. Connect the EL-50334-14 Infotainment Test Cable and the EL-50334-2 Type-A Female to Mini-B Male Cable together. Connect the assembled test cable to the K74 Human Machine Interface Control Module and the X83 Auxiliary Audio Input.

8. Ignition On/Vehicle in Service Mode. Infotainment system ON.

9. Connect the EL-50334-20 Multi-Media Interface Tester (MIT) to the X83 Auxiliary Audio Input USB port and select the USB test mode.

10. Verify the audio from the EL-50334-20 Multi-Media Interface Tester (MIT) is heard through the infotainment system while operating the system to play audio from the test tool.

If audio is not heard from the test tool

1. Replace the X83 Auxiliary Audio Input Adapter. Connect all harness connectors.

2. Connect the EL-50334-20 Multi-Media Interface Tester (MIT) to the X83 Auxiliary Audio Input USB port and select the USB test mode.

3. Verify the audio from the EL-50334-20 Multi-Media Interface Tester (MIT) is heard through the infotainment system while operating the system to play audio from the test tool.

If audio is not heard from the test tool, replace the K74 Human Machine Interface Control Module.

If audio is heard from the test tool

11. Connect the EL-50334-20 Multi-Media Interface Tester (MIT) to the X83 Auxiliary Audio Input AUX port and select the AUX test mode.

12. Verify the audio from the EL-50334-20 Multi-Media Interface Tester (MIT) is heard through the infotainment system while operating the system to play audio from the test tool.

If audio is not heard from the test tool

1. Replace the X83 Auxiliary Audio Input Adapter. Connect all harness connectors.

If audio is heard from the test tool.

13. Replace the vehicle USB cable between the K74 Human Machine Interface Control Module and the X83 Auxiliary Audio Input Adapter.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair. Refer to Audio Disc Player and USB Receptacle Replacement

Refer to Control Module References for human machine interface control module replacement, programming, and setup.

BLUETOOTH MALFUNCTION

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Refer to Diagnostic Procedure Instructions to provide an overview of each diagnostic category.

Circuit/System Description

Bluetooth® wireless technology is a short-range communications technology intended to replace the cables connecting portable and/or fixed devices while maintaining high levels of security. The operating range of the signal is approximately 30 feet.

The available features and functions are determined by the type of device and the software within the devices being used. For a feature or function to operate, it must be supported in both devices.

The Bluetooth® hardware is internal to the radio. The radio supports streaming of data (music, voice, information) from cellular phones and other mobile devices that support those features. The radio may also be capable of interfacing with cellular phones for hands-free features.

Refer to the vehicle owners manual, supplements, and the device manufacturers information for information on devices, control, operation. and pairing instructions.

Diagnostic Aids

Verify the mobile device is properly configured for the feature being used. Refer to the device manufacturers information.

Verify the function/feature that is being used is supported by the mobile device.

The device must be paired to the radio to use the available Bluetooth® feature(s). The pairing process must only be performed once for each device, unless that device's information is deleted.

The system can store pairing information for multiple devices, but can only be actively connected to one at any given time.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information Special Tools

EL-50334-20 Multi-Media Interface Tester (MIT)

Circuit/System Verification

1. Verify no DTCs are present.

If any DTCs are present

Refer to Diagnostic Trouble Code (DTC) List - Vehicle .

If no DTCs are present

2. Verify the radio calibrations are current.

If the radio calibrations are not current

Reprogram the radio and re-evaluate the concern.

If no update calibrations are available

NOTE: The MIT tool can be used to test either cellular phone or streaming audio functions. Refer to the tool instructions, and perform the appropriate test(s) related to the customers concern in the following steps.

3. Vehicle in Service Mode, infotainment system ON.

4. Verify the infotainment system successfully pairs with the MIT tool.

If the infotainment system does not successfully pair with the MIT tool.

Replace the A11 radio.

If the infotainment system successfully pairs with the MIT tool.

5. Verify the infotainment system successfully completes the desired feature test using the MIT tool.

If the feature test is not successful

Replace the A11 radio.

If the feature test is successful

6. All OK. Refer to Diagnostic Aids.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Control Module References for radio replacement, programming, and setup.

DIGITAL RADIO POOR OR NO RECEPTION

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Refer to Diagnostic Procedure Instructions to provide an overview of each diagnostic category.

DTC Descriptors

DTC B125C 01

Satellite Antenna Circuit Short to Battery

DTC B125C 02

Satellite Antenna Circuit Short to Ground

DTC B125C 04

Satellite Antenna Circuit Open

Circuit/System Description

The digital radio receiver, located inside the radio, receives digital radio information from the digital radio antenna located on the outside of the vehicle. The digital radio receiver is connected to the digital radio antenna via a shielded coax cable. The digital radio antenna contains an amplifier which is powered by the radio through the coax cable.

Conditions for Running the DTC

This DTC is run every 300 milliseconds.

Conditions for Setting the DTC

The radio detects a circuit fault in the digital radio antenna.

Action Taken When the DTC Sets

The radio displays No XM Signal or Check Antenna.

Conditions for Clearing the DTC

A current DTC clears when the condition for setting the DTC is no longer present. A history DTC clears after 100 malfunction-free ignition cycles.

Diagnostic Aids

The digital radio antenna requires a clear line of sight to the sky to operate properly. Reception may be limited, intermittent, or unavailable inside structures.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

Special Tools

EL-48028 Digital Radio Test Antenna

Circuit/System Verification

1. With the vehicle outside in an area with an unobstructed view of the southern sky, tune to XM.

2. Verify DTC B125C is not set as current and the No XM Signal message is not displayed on the radio.

If DTC B125C is set as current or the No XM Signal message is displayed.

Refer to Circuit/System Testing.

If DTC B125C is not set as current and the No XM Signal message is not displayed.

3. All OK.

Circuit/System Testing

1. Ignition OFF/Vehicle OFF, disconnect the digital radio antenna coax cable from the A11 Radio. Connect the

EL-48028 Digital Radio Test Antenna to the radio and place on the roof of the vehicle.

2. Ignition ON/Vehicle in Service Mode, radio tuned to XM channel 1.

3. Verify DTC B125C is not set as current and XM reception is improved.

If DTC B125C is set as current or XM reception is not improved

Replace the A11 Radio.

If DTC B125C is not set as current and XM reception is improved

4. Ignition OFF/Vehicle OFF, disconnect the digital radio antenna coax cable from the T2RR Antenna - Roof Rear.

5. Verify the digital radio antenna coax cable passes the coax cable component test. Refer to Component Testing.

If the coax cable does not pass the test

Replace the antenna coax cable

If the coax cable passes the test

6. Test or replace the T2RR Antenna - Roof Rear.

Component Testing

CAUTION: Refer to Test Probe Caution .

NOTE: Before testing the coax cable, check the cable exterior for being pinched, cut,

damaged, or having loose connections at the components, which can cause reception issues.

To prevent false reading when testing the center coax terminals, use care not to ground the test probe on the outer housing/shield.

Coax Cable Test

1. Ignition OFF/Vehicle OFF, disconnect the coax cable at both components.

2. Test for less than 5 Ω between coax cable center terminal end to end.

If 5 Ω or greater

Replace the coax cable

If less than 5 Ω

3. Test for less than 5 Ω between the coax cable outer shield end to end.

If 5 Ω or greater

Replace the coax cable

If less than 5 Ω

4. Test for infinite resistance between the coax cable center terminal and the coax cable outer shield.

If less than infinite resistance

Replace the coax cable

If infinite resistance

5. All OK

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to High Frequency Antenna Replacement

Refer to Control Module References for radio replacement, programming, and setup.

ONSTAR MICROPHONE MALFUNCTION

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Refer to Diagnostic Procedure Instructions to provide an overview of each diagnostic category.

Diagnostic Fault Information

Circuit/System Description

The telematics communication interface control module provides the Cellular Phone Microphone with a supplied voltage on the cellular phone microphone signal circuit. When the cellular phone microphone is in use, voice data from the user is sent back to the telematics communication interface control module on the signal circuit.

Reference Information

Schematic Reference

OnStar/Telematics Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

OnStar Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

NOTE: It is necessary to have the vehicle in a quiet, open outside area where a cellular call can be successfully placed and GPS data can be received from satellites.

1. Vehicle in Service Mode.

2. Verify that DTC B2455 is not set.

If DTC B2455 is set

Refer to DTC B2455.

If DTC B2455 is not set

3. Verify that a successful OnStar voice command can be made.

If your voice can not be heard clearly

Refer to Circuit/System Testing - Microphone Malfunction.

If your voice can be heard clearly

4. Verify that your voice is heard clearly by the OnStar Call Center after completing a blue button press.

If your voice can not be heard clearly

Refer to Circuit/System Testing - Cellular Telephone Voice Malfunction.

If your voice can be heard clearly

5. All OK.

Circuit/System Testing

Microphone Malfunction

1. Vehicle OFF, disconnect the harness connector at the B24 Cellular Phone Microphone, vehicle in Service Mode.

2. Test for 8.0-10.5 V between the signal circuit terminal B and ground.

If less than 8.0 V

1. Vehicle OFF, disconnect the X2 harness connector at the K73 Telematics Communication Interface Control Module.

2. Test for infinite resistance between the signal circuit and ground.

If less than infinite resistance, repair the short to ground in the circuit. If infinite resistance

3. Test for less than 2 Ω in the signal circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit.

If less than 2 Ω, replace the vehicle K73 Telematics Communication Interface Control Module.

If greater than 10.5 V

1. Vehicle OFF, disconnect the X2 harness connector at the K73 Telematics Communication Interface Control Module, vehicle in Service Mode.

2. Test for less than 1 V between the signal circuit and ground.

If 1 V or greater, repair the short to voltage on the circuit.

If less than 1 V, replace the K73 Telematics Communication Interface Control Module.

If between 8.0-10.5 V

3. Test for less than 1 V between the signal circuit terminal A and ground.

If greater than 1 V

1. Vehicle OFF, disconnect the X2 harness connector at the K73 Telematics Communication Interface Control Module, vehicle in Service Mode.

2. Test for less than 1 V between the signal circuit and ground.

If 1 V or greater, repair the short to voltage in the circuit.

If less than 1 V, repair the K73 Telematics Communication Interface Control Module.

If less than 1 V

4. Test for greater than 8 V between the signal circuit terminal B and the signal circuit terminal A.

If less than 8 V

1. Vehicle OFF, disconnect the X2 harness connector at the K73 Telematics Communication Interface Control Module.

2. Test for infinite resistance between the signal circuit and ground.

If less than infinite resistance, repair the short to ground in the circuit. If infinite resistance

3. Test for less than 2 Ω in the signal circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit.

If less than 2 Ω, replace the vehicle K73 Telematics Communication Interface Control Module.

If greater than 9 V

5. Test or replace the B24 Cellular Phone Microphone.

Cellular Telephone Voice Malfunction

1. Vehicle OFF and vehicle systems OFF, disconnect the X2 harness connector at the K73 Telematics Communication Interface Control Module and the X4 harness connector at the A11 Radio, vehicle in Service Mode.

2. Test for less than 1 V between the signal circuits listed below and ground.

K73 Telematics Communication Interface Control Module signal circuit Terminal 6 K73 Telematics Communication Interface Control Module signal circuit Terminal 12 If greater than 1 V

Repair the short to voltage in the circuit.

If less than 1 V

3. Vehicle OFF.

4. Test for infinite resistance between the signal circuits listed below and ground.

K73 Telematics Communication Interface Control Module signal circuit Terminal 6 K73 Telematics Communication Interface Control Module signal circuit Terminal 12 If less than infinite resistance

Repair the short to ground on the circuit.

If infinite resistance

5. Test for less than 2 Ω in the signal circuits listed below end to end.

K73 Telematics Communication Interface Control Module signal circuit Terminal 6 K73 Telematics Communication Interface Control Module signal circuit Terminal 12 If 2 Ω or greater

Repair the open/high resistance in the circuit.

If less than 2 Ω

6. Replace the K73 Telematics Communication Interface Control Module.

7. Verify that your voice is heard clearly by the OnStar Call Center after completing a blue button press.

If your voice can not be heard clearly

Replace the A11 Radio.

If your voice can be heard clearly

8. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair procedure.

Refer to Mobile Telephone Microphone Replacement

Refer to Control Module References for telematics communication interface control module replacement, programming, and setup

NAVIGATION SYSTEM - VOICE RECOGNITION MALFUNCTION

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Refer to Diagnostic Procedure Instructions to provide an overview of each diagnostic category.

Diagnostic Fault Information

Circuit/System Description

When voice recognition for the navigation equipped infotainment system is started, voice signals from the cellular phone microphone are passed through the telematics communication interface control module to the radio via the voice recognition audio circuits.

Diagnostic Aids

Refer to the Navigation System Owners Manual for voice recognition use and commands. Navigation voice commands are not available until the OK button has been selected.

If the radio is off, the only commands available will be Hands Free and Help.

When the system recognizes the command the system will either perform the function or ask to confirm the choice by clearly saying "yes" or "no".

If experiencing difficulty with the system recognizing a command, confirm that the command is correct.

Background noise such as a climate control fan positioned on high, open windows, or very loud outside noises,

can cause voice commands to be misunderstood.

Reference Information

Schematic Reference

OnStar/Telematics Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Verify the OnStar® voice recognition system is operating normally.

If the OnStar® voice recognition system is not operating normally.

Refer to OnStar Voice Recognition Malfunction.

If the OnStar® voice recognition system is operating normally.

2. Vehicle in Service Mode, radio ON.

NOTE: Refer to the Navigation System Owners Manual for voice recognition use and commands.

3. Begin voice recognition for the radio and clearly speak one of the available commands.

4. Verify the infotainment system responds correctly to the command.

If the infotainment system does not respond correctly to the command.

1. Clearly speak a different command.

2. Verify the infotainment system responds correctly to the command.

If the infotainment system does not respond correctly to any commands, refer to Circuit/System Testing.

If the infotainment system responds correctly to the command.

3. Refer to the navigation system owners manual for hints on speaking commands.

If the infotainment system responds correctly to the command.

5. All OK

Circuit/System Testing

1. Vehicle OFF, disconnect the X2 harness connector at the K73 Telematics Communication Interface Control Module Control Module and the X4 harness connector at the A11 Radio.

2. Vehicle in Service Mode.

3. Test for less than 1 V between the signal circuits listed below and ground: voice recognition signal circuit A11 Radio X4 terminal 6

voice recognition low reference circuit A11 Radio X4 terminal 16

If 1 V greater

Repair the short to voltage on the circuit.

If less than 1 V

4. Vehicle OFF.

5. Test for infinite resistance between the circuits listed below and ground: voice recognition signal circuit A11 Radio X4 terminal 6

voice recognition low reference circuit A11 Radio X4 terminal 16

If less than infinite resistance

Repair the short to ground on the circuit.

If infinite resistance

6. Test for less than 5 Ω between the terminals listed below:

A11 Radio X4 terminal 6 and the K73 Telematics Communication Interface Control Module Control Module X2 terminal 6

A11 Radio X4 terminal 16 and the K73 Telematics Communication Interface Control Module Control Module X2 terminal 12

If 5 Ω greater

Repair the open/high resistance in the circuit.

If less than 5 Ω

7. Replace the A11 Radio. Connect all harness connectors.

NOTE: Refer to the Navigation System Owners Manual for voice recognition use and commands.

8. Begin voice recognition for the radio and clearly speak one of the available commands.

9. Verify the infotainment system responds correctly to the command.

If the infotainment system does not respond correctly to the command

1. Clearly speak a different command.

2. Verify the infotainment system responds correctly to the command.

If the infotainment system does not respond correctly to any commands, replace the K73 Telematics Communication Interface Control Module.

If the infotainment system responds correctly to the command

10. All OK

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Control Module References for radio or telematics communication interface control module replacement, programming, and setup.

ONSTAR AUDIO MALFUNCTION

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Refer to Diagnostic Procedure Instructions to provide an overview of each diagnostic category.

Diagnostic Fault Information

Circuit/System Description

When an OnStar® keypress is made, a serial data message is sent to the audio system to mute all radio functions and output OnStar® originated audio. After the audio system is muted, the telematics communication interface control module transmits signals to the audio system on the audio signal and audio common circuits.

Reference Information

Schematic Reference

OnStar/Telematics Schematics

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

OnStar Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Vehicle in Service Mode, radio ON.

2. Verify that audio is heard clearly through all speaker channels when tuning radio to a known good station.

If audio is not heard clearly

Refer to Speaker Malfunction

If audio is heard clearly

3. Verify that the Connecting to OnStar® message is heard clearly through the audio system when the OnStar® blue button is pressed.

If OnStar message is noisy or distorted

Refer to Circuit/System Testing

If OnStar message is heard clearly

4. All OK.

Circuit/System Testing

1. Vehicle OFF, disconnect the X1 harness connector at the A11 Radio and the X2 harness connector at the K73 Telematics Communication Interface Control Module, vehicle in Service Mode.

2. Test for less than 1 V between the signal circuit terminals listed below and ground:

K73 Telematics Communication Interface Control Module signal circuit terminal 1 X2 K73 Telematics Communication Interface Control Module signal circuit terminal 2 X2 If 1 V or greater

Repair the short to voltage on the circuit.

If less than 1 V

3. Vehicle OFF.

4. Test for infinite resistance between the signal circuits listed below and ground:

K73 Telematics Communication Interface Control Module signal circuit terminal 1 X2 K73 Telematics Communication Interface Control Module signal circuit terminal 2 X2 If less than infinite resistance

Repair the short to ground on the circuit.

If infinite resistance

5. Test for less than 2 Ω between the signal circuit terminals listed below:

K73 Telematics Communication Interface Control Module signal circuit terminal 1 X2 and the A11 Radio signal circuit terminal 20 X1

K73 Telematics Communication Interface Control Module signal circuit terminal 2 X2 and the A11

Radio signal circuit terminal 19 X1

If 2 Ω or greater

Repair the open/high resistance in the circuit.

If less than 2 Ω

6. Replace the K73 Telematics Communication Interface Control Module.

7. Verify that the Connecting to OnStar® message is heard clearly through the audio system when the OnStar® blue button is pressed.

If audio is not heard clearly

Replace the A11 Radio.

If audio is heard clearly

8. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Control Module References for module replacement, programming, and setup.

NO GLOBAL POSITIONING SYSTEM (GPS) RECEPTION

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Refer to Diagnostic Procedure Instructions to provide an overview of each diagnostic category.

DTC Descriptors

DTC B2462 02

Global Positioning System Short to Ground

DTC B2462 04

Global Positioning System Open

Circuit/System Description

The navigation antenna is connected to the Telematics Communication Interface Control Module. The module supplies 5 V to the antenna to power the internal amplifier through the center conductor of the antenna coax cable.

When the vehicle is equipped with the optional navigation system, a Navigation Antenna Signal Splitter is installed to distribute the navigation signal to both the Telematics Communication Interface Control Module and the Human Machine Interface Control Module. The Human Machine Interface Control Module supplies 5 V through the coax cable to power the Navigation Antenna Signal Splitter.

Conditions for Running the DTC

Radio On.

System voltage is greater than 9 V and less than 16 V.

The navigation system/telematics communication interface control module tests the GPS antenna every 10 s.

Conditions for Setting the DTC

B2462 02

The Telematics Communication Interface Control Module or Human Machine Interface Control Module detects a short to ground on the GPS antenna signal circuit.

B2462 04

The Telematics Communication Interface Control Module or Human Machine Interface Control Module detects a open/high resistance on the GPS antenna signal circuit.

Action Taken When the DTC Sets

The Telematics Communication Interface Control Module or Human Machine Interface Control Module uses the last reported position and the vehicle speed signal to calculate the vehicle position.

Route guidance may be inaccurate.

Turn by turn navigation may be inaccurate or inoperative.

Conditions for Clearing the DTC

The condition responsible for setting the DTC no longer exists.

A history DTC will clear once 50 consecutive malfunction - free ignition cycles have occurred.

Diagnostic Aids

The scan tool Telematics Communication Interface Control Module GPS signal parameter will display a Yes or No dependent upon whether or not the module sees an increment of the seconds transmitted by GPS signals to the Telematics Communication Interface Control Module. Upon entering this screen, the GPS signal title will initially display Yes, regardless of the presence of time increment, for at least 2 seconds, while the algorithm in the scan tool determines the status of the clock. If increment is found, Yes is continually displayed. If the clock remains static, No is displayed. The scan tool looks for increment every second, regardless of current display.

Inaccurate or aged GPS position concerns which are no longer present may have been due to the temporary loss of GPS signal reception by the vehicle. Conditions such as tunnels or parking structures will restrict the cellular phone and navigation antenna from a clear view of the satellites in the sky and may have caused this temporary data loss.

The GPS requires a clear line of sight to the sky to operate properly. In most cases the GPS will not have reception near tall buildings or inside structures.

Reference Information

Schematic Reference

OnStar/Telematics Schematics

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

OnStar Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information Special Tools

EL-49903 OnStar Antenna Diagnostic Tool Kit

Circuit/System Verification

NOTE: The following verification requires the vehicle to be outside with an unobstructed view of the southern sky. Allow 5 minutes after turning the ignition ON for the vehicle to acquire the GPS satellites signal.

1. Ignition ON/vehicle in Service Mode.

2. Verify that DTC B2462 is not set in the Telematics Communication Interface Control Module.

If DTC B2462 is set in the Telematics Communication Interface Control Module and the vehicle is not equipped with a navigation system

Refer to Circuit/System Testing Without Navigation System.

If DTC B2462 is set in the Telematics Communication Interface Control Module and the vehicle is equipped with a navigation system

Refer to Circuit/System Testing With Navigation System.

If DTC B2462 is not set in the Telematics Communication Interface Control Module

3. Verify an OnStar advisor can locate the vehicle after performing a blue button press.

If the advisor can not locate the vehicle and the vehicle is not equipped with a navigation system

Refer to Circuit/System Testing Without Navigation System

If the advisor can not locate the vehicle and the vehicle is equipped with a navigation system

Refer to Circuit/System Testing With Navigation System.

If the advisor can locate the vehicle

4. Verify DTC B2462 is not set in the Human Machine Interface Control Module.

If DTC B2462 is set in the Human Machine Interface Control Module

Refer to Circuit/System Testing With Navigation System - Step 9.

If DTC B2462 is not set in the Human Machine Interface Control Module

5. Verify that the NO GPS symbol/message is not displayed on the radio display.

If the NO GPS symbol/message is displayed

Refer to Circuit/System Testing With Navigation System - Step 9.

If the NO GPS symbol/message is not displayed

6. All OK.

Circuit/System Testing

without Navigation System

NOTE: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

1. Ignition OFF/vehicle OFF, disconnect the GPS and cellular coax cable connector at the K73 Telematics Communication Interface Control Module.

2. Attach both leads of the EL-49903-1 OnStar test antenna to the EL-49903-5 combiner. Using the EL-49903-6 coax cable attach the grey connector to the combiner and the brown connector to the K73 Telematics Communication Interface Control Module. Place the test antenna on the roof of the vehicle, ignition ON.

3. Verify DTC B2462 is not set or that the OnStar advisor can locate the vehicle.

If DTC B2462 is set or the advisor can not locate the vehicle

Replace the K73 Telematics Communication Interface Control Module.

If DTC B2462 is not set or the advisor can locate the vehicle

4. Test the coax cable between the K73 Telematics Communication Interface Control Module and the T2RR Antenna - Roof Rear. Refer to component testing.

If the coax cable does not pass the test

Replace the coax cable.

If the coax cable passes the test

5. Test or replace the T2RR Antenna - Roof Rear.

with Navigation System

NOTE: You must perform the Circuit/System Verification before proceeding with Circuit/System Testing.

1. Ignition OFF/vehicle OFF, disconnect the T2RR Antenna - Roof Rear coax cable at the T15 Navigation Antenna Signal Splitter.

2. Attach both leads of the EL-49903-1 OnStar test antenna to the EL-49903-5 combiner. Using the EL-49903-7 coax cable attach one grey connector to the combiner and the other grey connector to the T15 Navigation Antenna Signal Splitter. Place the test antenna on the roof of the vehicle, ignition ON.

3. Verify DTC B2462 is not set or that the OnStar advisor can locate the vehicle.

If DTC B2462 is not set or the advisor can locate the vehicle

1. Test the coax cable between the T15 Navigation Antenna Signal Splitter and the T2RR Antenna - Roof Rear. Refer to Component Testing.

If the coax cable does not pass the test Replace the coax cable.

If the coax cable passes the test

2. Replace the T2RR Antenna - Roof Rear.

If DTC B2462 is set or if the advisor can not locate the vehicle

4. Ignition OFF/vehicle OFF, disconnect the GPS and cellular coax cable connector at the K73 Telematics Communication Interface Control Module.

5. Attach both leads of the EL-49903-1 OnStar test antenna to the EL-49903-5 combiner. Using the EL-49903-6 coax cable attach the grey connector to the combiner and the brown connector to the K73 Telematics Communication Interface Control Module. Place the test antenna on the roof of the vehicle, ignition ON.

6. Verify DTC B2462 is not set or that the OnStar advisor can locate the vehicle.

If DTC B2462 is set or the advisor can not locate the vehicle.

Replace the K73 Telematics Communication Interface Control Module.

If DTC B2462 is not set or the advisor can locate the vehicle.

7. Ignition OFF/vehicle OFF.

8. Test the coax cable between the T15 Navigation Antenna Signal Splitter and the K73 Telematics Communication Interface Control Module. Refer to Component Testing.

If the coax cable does not pass the test.

Replace the coax cable.

If the coax cable passes the test.

9. Ignition OFF/vehicle OFF, disconnect the blue GPS coax cable connector at the K74 Human Machine Interface Control Module.

10. Attach the EL-49903-1 OnStar test antenna blue connector to the K74 Human Machine Interface Control Module and place the test antenna on the roof of the vehicle.

11. Ignition ON/vehicle in Service Mode.

12. Verify DTC B2462 is not set or that the NO GPS symbol/message is not displayed on the radio.

If DTC B2462 is set or the NO GPS symbol/message is displayed

Replace the K74 Human Machine Interface Control Module

If DTC B2462 is not set or if the NO GPS symbol/message is not displayed.

13. Ignition OFF/vehicle OFF.

14. Test the coax cable between the T15 Navigation Antenna Signal Splitter and the K74 Human Machine Interface Control Module. Refer to Component Testing.

If the coax cable does not pass the test.

Replace the coax cable.

If the coax cable passes the test.

15. Test or replace the T15 Navigation Antenna Signal Splitter.

Component Testing

CAUTION: Refer to Test Probe Caution .

NOTE: Before testing the coax cable, check the cable exterior for being pinched, cut, damaged, or having loose connections at the components, which can cause reception issues.

To prevent false reading when testing the center coax terminals, use care not to ground the test probe on the outer housing/shield.

The vehicle may be equipped with sectioned coax. Test each section and replace only the faulty section, not the entire length of coax.

Coax Cable Test

1. Ignition OFF/vehicle OFF, disconnect the coax cable at both components.

2. Test for less than 5 Ω between the coax cable center terminal end to end.

If 5 Ω or greater

Replace the coax cable.

If less than 5 Ω

3. Test for greater than 5 Ω between the coax cable outer shield end to end.

If 5 Ω or greater

Replace the coax cable.

If less than 5 Ω

4. Test for infinite resistance between the coax cable center terminal and the coax cable outer shield.

If less than infinite resistance

Replace the coax cable.

If infinite resistance

5. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to High Frequency Antenna Replacement

Refer to Control Module References for Human Machine Interface control module or Telematics Communication Interface Control Module replacement, programming, and setup.

ONSTAR BUTTON LED MALFUNCTION

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Refer to Diagnostic Procedure Instructions to provide an overview of each diagnostic category.

Diagnostic Fault Information

Circuit Description

The OnStar® status LEDs are located with the OnStar buttons. The green LED is illuminated when the system is ON and operating normally. When the green LED is green and flashing, it is an indication that a call is in progress. When the red LED is illuminated, a system malfunction is present. In the event there is a system malfunction and the OnStar® system is still able to make a call, the LED will flash red during the call. The OnStar® LEDs are controlled by the telematics communication interface control module via the keypad green LED signal circuit and the keypad red LED signal circuit.

Reference Information

Schematic Reference

OnStar/Telematics Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

OnStar Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

NOTE: If the green LED is off with the ignition ON and the LED does not function when commanded with the scan tool, contact the OnStar Center to confirm the vehicle has a current subscription.

1. Vehicle in Service Mode/Ignition ON.

2. Verify no DTCs are set.

If any DTCs are set

Refer to Diagnostic Trouble Code (DTC) List - Vehicle

If no DTCs are set

3. Verify that the green LED turns ON and OFF when commanding the Green Indicator ON and OFF with a scan tool.

If the green LED does not turn ON and OFF

Refer to Circuit/System Testing - Green LED Test

If the green LED turns ON and OFF

4. Verify that the red LED turns ON and OFF when commanding the Red Indicator ON and OFF with a scan tool.

If the red LED does not turn ON and OFF

Refer to Circuit/System Testing - Red LED Test

If the red LED turns ON and OFF

5. All OK.

Circuit/System Testing

Green LED Test

1. Vehicle OFF/Ignition OFF, and all vehicle systems OFF, disconnect the harness connector at the S48B Multifunction Switch - Overhead Console. It may take up to 2 min for all vehicle systems to power down. Doors closed, courtesy lamps OFF.

2. Test for less than 10 Ω between the ground circuit terminal 5 and ground.

If 10 Ω or greater

1. Vehicle OFF/Ignition OFF.

2. Test for less than 2 Ω in the ground circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit.

If less than 2 Ω, repair the open/high resistance in the ground connection.

If less than 10 Ω

3. Vehicle in Service Mode/Ignition ON.

4. Test for less than 1 V between the control circuit terminal 15 and ground while commanding the Green Indicator OFF with a scan tool.

If 1 V or greater

1. Vehicle OFF/Ignition OFF, disconnect the X1 harness connector at the K73 Telematics Communication Interface Control Module, vehicle in Service Mode/Ignition ON.

2. Test for less than 1 V between the control circuit terminal 15 and ground. If 1 V or greater, repair the short to voltage on the circuit.

If less than 1 V, replace the K73 Telematics Communication Interface Control Module.

If less than 1 V

5. Test for greater than 8 V between the control circuit terminal 15 and ground while commanding the Green Indicator ON with a scan tool.

If 8 V or less

1. Vehicle OFF/Ignition OFF, disconnect the X1 harness connector at the K73 Telematics Communication Interface Control Module.

2. Test for infinite resistance between the control circuit terminal 15 and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance

3. Test for less than 2 Ω in the control circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit.

If less than 2 Ω, replace the K73 Telematics Communication Interface Control Module.

If greater than 8 V

6. Test or replace the S48B Multifunction Switch - Overhead Console.

Red LED Test

1. Vehicle OFF/Ignition OFF, and all vehicle systems OFF, disconnect the harness connector at the S48B Multifunction Switch - Overhead Console. It may take up to 2 min for all vehicle systems to power down. Doors closed, courtesy lamps OFF.

2. Test for less than 10 Ω between the ground circuit terminal 5 and ground.

If 10 Ω or greater

1. Vehicle OFF/Ignition OFF.

2. Test for less than 2 Ω in the ground circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit.

If less than 2 Ω, repair the open/high resistance in the ground connection.

If less than 10 Ω

3. Vehicle in Service Mode/Ignition ON.

4. Test for less than 1 V between the control circuit terminal 14 and ground while commanding the Red Indicator OFF with a scan tool.

If 1 V or greater

1. Vehicle OFF/Ignition OFF, disconnect the X1 harness connector at the K73 Telematics Communication Interface Control Module, vehicle in Service Mode/Ignition ON.

2. Test for less than 1 V between the control circuit terminal 14 and ground. If 1 V or greater, repair the short to voltage on the circuit.

If less than 1 V, replace the K73 Telematics Communication Interface Control Module.

If less than 1 V

5. Test for greater than 8 V between the control circuit terminal 14 and ground while commanding the Red Indicator ON with a scan tool.

If 8 V or less

1. Vehicle OFF/Ignition OFF, disconnect the X1 harness connector at the K73 Telematics Communication Interface Control Module.

2. Test for infinite resistance between the control circuit terminal 14 and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance

3. Test for less than 2 Ω in the control circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit.

If less than 2 Ω, replace the K73 Telematics Communication Interface Control Module.

If greater than 8 V

6. Test or replace the S48B Multifunction Switch - Overhead Console.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair procedure.

Refer to Roof Console Replacement

Refer to Control Module References for control module replacement, programming and setup

ONSTAR CALL CENTER REMOTE FUNCTION REQUESTS MALFUNCTION

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Refer to Diagnostic Procedure Instructions to provide an overview of each diagnostic category.

Circuit/System Description

The telematics communication interface control module has the capability of commanding the horn, initiating door lock/unlock, or operating the exterior lamps using the serial data circuits. These functions are commanded by the OnStar® Call Center per a customer request.

Diagnostic Aids

The customer concern may have been due to a lack of cellular service in a given area, or a failure in the National Cellular Network infrastructure that has since been corrected.

Reference Information

Schematic Reference

OnStar/Telematics Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

OnStar Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

NOTE: It is necessary to inform the OnStar® Call Center advisor that this call is for vehicle diagnostic purposes.

It is necessary to have the vehicle in an open outside area where a cellular call can be successfully placed and GPS data can be received from satellites.

1. Vehicle in Service Mode.

2. Verify that the horn, lights, and the door locks on the vehicle operate properly.

If an applicable vehicle system does not operate properly

Refer to Diagnostic System Check - Vehicle .

If all applicable vehicle systems operate properly

3. Verify that a call can be successfully placed to the OnStar Call Center by pressing the blue OnStar button.

If unable to contact the OnStar® call center

Refer to Unable to Contact OnStar Call Center

If able to contact the OnStar Call Center

4. Verify with the OnStar advisor that all remote functions (door locks, lights, and horn) work.

If the remote functions do not operate when requested

Replace the K73 telematics communication interface control module

If the remote functions operate when requested

5. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Control Module References for telematics communication interface control module replacement, programming and setup.

ONSTAR BUTTON MALFUNCTION

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Refer to Diagnostic Procedure Instructions to provide an overview of each diagnostic category.

Diagnostic Fault Information

Circuit/System Description

The OnStar® button assembly consists of 3 buttons, Call/Answer, OnStar® Call Center, and OnStar® Emergency. The telematics communication interface control module supplies the OnStar® button assembly with 10 V via the keypad supply voltage circuit. Each of the buttons, when pressed, completes the circuit across a resistor allowing a specific voltage to be returned to the telematics communication interface control module over the keypad signal circuit. Depending upon the voltage range returned, the telematics communication interface control module is able to identify which button has been activated.

Reference Information

Schematic Reference

OnStar/Telematics Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

NOTE: Contact the OnStar® Call Center first before pressing the emergency button in order to notify them of the test.

1. Vehicle in Service Mode.

2. Verify no DTCs are set.

If any DTCs are set

Refer to Diagnostic Trouble Code (DTC) List - Vehicle

If no DTCs are set

3. Verify that each OnStar® button operates normally by pressing each button individually.

If none of the buttons operate normally

Refer to Circuit System Testing.

If some, but not all, of the buttons operate normally

Test or replace the S48B Multifunction Switch - Overhead Console.

If all of the buttons operate normally

4. All OK.

Circuit/System Testing

1. Vehicle OFF and all vehicle systems OFF, disconnect the harness connector at the S48B Multifunction Switch

- Overhead Console. It may take up to 2 min for all vehicle systems to power down.

2. Test for less than 10 Ω between the ground circuit terminal 5 and ground.

If 10 Ω or greater

1. Vehicle OFF.

2. Test for less than 2 Ω in the ground circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit.

If less than 2 Ω, repair the open/high resistance in the ground connection.

If less than 10 Ω

3. Vehicle in Service Mode.

4. Test for 8.0 - 10.5 V between the 10 V reference circuit terminal 16 and ground.

If less than 8.0 V

1. Vehicle OFF, disconnect the harness connector at the K73 Telematics Communication Interface Control Module.

2. Test for infinite resistance between the 10 V reference circuit and ground.

If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance

3. Test for less than 2 Ω in the 10 V reference circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit.

If less than 2 Ω, replace the K73 Telematics Communication Interface Control Module.

If greater than 10.5 V

1. Vehicle OFF, disconnect the harness connector at the K73 Telematics Communication Interface Control Module, vehicle in Service Mode.

2. Test for less than 1 V between the 10 V reference circuit and ground. If 1 V or greater, repair the short to voltage on the circuit.

If less than 1 V, replace the K73 Telematics Communication Interface Control Module.

If between 8.0 - 10.5 V

5. Vehicle OFF.

6. Test for 500 - 900 Ω between the signal circuit terminal 17 and ground.

If less than 500 Ω

1. Disconnect the X1 harness connector at the K73 Telematics Communication Interface Control Module.

2. Test for infinite resistance between the signal circuit and ground.

If less than infinite resistance, repair the short to ground on the circuit.

If infinite resistance, replace the K73 Telematics Communication Interface Control Module.

If greater than 900 Ω

1. Disconnect the X1 harness connector at the K73 Telematics Communication Interface Control Module, vehicle in Service Mode.

2. Test for less than 1 V between the signal circuit and ground.

If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V

3. Vehicle OFF.

4. Test for less than 2 Ω in the signal circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit.

If less than 2 Ω, replace the K73 Telematics Communication Interface Control Module.

If between 500 - 900 Ω

7. Test or replace the S48B Multifunction Switch - Overhead Console.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair procedure.

Refer to Roof Console Replacement

Refer to Control Module References for control module replacement, programming and setup

ONSTAR STEERING WHEEL CONTROL FUNCTIONS MALFUNCTION

Some vehicles equipped with the OnStar® system have the capability of accessing voice mailboxes and other automated phone systems by means of the steering wheel controls, while the OnStar® Personal Calling feature is in use. If the "Talk" or "Mute" button (depending upon the vehicle) on the steering wheel controls is depressed during an OnStar® Personal Calling call, the telematics communication interface control module receives the message on the serial data bus from either the radio or body control module. This message is interpreted as a request to turn any spoken numbers into dual tone multi-frequency tones to be delivered over the airwaves to the phone system the user is communicating with. Complete instructions for operation of these features can be found in the information provided to the customer with the OnStar® system.

The steering wheel controls are a resistor network that consist of multiple momentary contact switches and a series of resistors. The switches and resistor network are arranged so that each switch has a different resistance value.

When a switch is pressed, a voltage drop occurs in the resistor network, which produces a specific voltage value unique to the switch selected, to be interpreted by either the radio or BCM. In the event the OnStar® steering wheel control functions are inoperative, technicians should refer to Steering Wheel Controls Malfunction , to begin diagnosis of the steering wheel control concern.

RADIO POOR RECEPTION

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Refer to Diagnostic Procedure Instructions to provide an overview of each diagnostic category.

DTC Descriptors

DTC B125A 02

Antenna Signal Circuit Short to Ground

DTC B125A 04

Antenna Signal Circuit Open Circuit

DTC B125A 01

Antenna Signal Circuit Short to Battery

Diagnostic Fault Information

Circuit/System Description

The radio antenna for AM and FM radio reception is connected to the radio with a coaxial cable.

Conditions for Running the DTC

Ignition ON/Vehicle in Service Mode.

Battery voltage must be between 9 - 16 V.

Conditions for Setting the DTC

B125A 02

The radio detects a short to ground in the antenna signal circuit center conductor.

B125A 04

The radio detects an open in the antenna signal circuit center conductor.

B125A 01

The radio detects a short to battery in the antenna signal circuit center conductor.

Action Taken When the DTC Sets

Radio reception may be poor or not available.

Conditions for Clearing the DTC

The condition responsible for setting the DTC no longer exists.

A history DTC will clears after 50 consecutive malfunction-free ignition cycles have occurred.

Diagnostic Aids

Poor AM and FM radio reception is dependent on multiple influences, some of which may not be vehicle related. Areas which have high RF traffic or block the signal path may cause a degradation in radio reception. Radio reception may also be influenced by items within the vehicle, but are not part of the radio system. Such examples are aftermarket electrical accessories or other items which may generate noise in the vehicle electrical system.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Inspect the antenna for proper mounting or physical damage.

If damage is found

Repair or replace as necessary

If no damage is found

2. Ignition ON/Vehicle in Service Mode, A11 Radio ON.

3. Verify station reception is normal when tuned to several known good AM and FM stations.

If AM or FM reception is poor.

Refer to Circuit/System Testing

If reception is normal

4. All OK.

Circuit/System Testing

1. Ignition OFF/Vehicle OFF, disconnect the radio antenna coax cable from the A11 Radio and from the T2RR Antenna - Roof Rear.

2. Verify the antenna coax cable passes the coax cable component test. Refer to Component Testing.

If the coax cable does not pass the test

Replace the antenna coax cable

If the coax cable passes the test

3. Connect the antenna coax cable to the T2RR Antenna - Roof Rear.

4. Test for infinite resistance between the coax cable center terminal and the coax cable outer shield at the radio end of the coax cable.

If less than infinite resistance

Replace the radio antenna base.

If infinite resistance

5. Test for less than 10 Ω between the coax cable outer shield and ground at the radio end of the coax cable.

If 10 Ω or greater

1. Clean the mounting surface of the radio antenna base.

2. Connect the antenna coax cable to the T2RR Antenna - Roof Rear.

3. Test for less than 10 Ω between the coax cable outer shield and ground at the radio end of the coax cable.

If 10 Ω or greater, replace the antenna base.

If less than 10 Ω, connect all harness connectors. Verify station reception is normal when tuned to several known good AM and FM stations. If AM or FM reception concerns are still present, replace the A11 Radio.

If less than 10 Ω

6. Test or replace the A11 Radio.

Component Testing

CAUTION: Refer to Test Probe Caution .

NOTE: Before testing the coax cable, check the cable exterior for being pinched, cut, damaged, or having loose connections at the components, which can cause reception issues.

To prevent false reading when testing the center coax terminals, use care not to ground the test probe on the outer housing/shield.

Coax Cable Test

1. Ignition OFF/Vehicle OFF, disconnect the coax cable at both components.

2. Test for less than 5 Ω between coax cable center terminal end to end.

If 5 Ω or greater

Replace the coax cable

If less than 5 Ω

3. Test for less than 5 Ω between the coax cable outer shield end to end.

If 5 Ω or greater

Replace the coax cable

If less than 5 Ω

4. Test for infinite resistance between the coax cable center terminal and the coax cable outer shield.

If less than infinite resistance

Replace the coax cable

If infinite resistance

5. All OK

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Refer to High Frequency Antenna Replacement

Refer to Control Module References for radio replacement, programming, and setup.

SPEAKER REPLACEMENT REFERENCE

SPEAKER MALFUNCTION

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Refer to Diagnostic Procedure Instructions to provide an overview of each diagnostic category.

Diagnostic Fault Information

Circuit/System Description

Each of the audio output channel circuits (+) and (-), at the radio and audio amplifier (if equipped) have a DC bias voltage that is approximately one half of battery voltage. When using a DMM, each of the audio output channel circuits will measure approximately 6.5 V DC. The audio being played on the system is produced by a varying AC voltage that is centered around the DC bias voltage on the same circuit. The AC voltage is what causes the speaker cone to move and produce sound. The frequency (Hz) of the AC voltage signal is directly related to the frequency of the input (audio source playing) to the audio system. Both the DC bias voltage and the AC voltage signals are needed for the audio system to properly produce sound.

Diagnostic Aids

Improper speaker mounting or loose trim may cause an audible buzz or distortion. Inspect the appropriate speaker and the surrounding interior trim for proper and secure mounting.

The EL-50334-6 Audio System Diagnostic CD contains audio tracks that can be used to duplicate and isolate such concerns. Tracks 11 and 12 contain audio sweep tones for testing for speaker and grill rattles.

If the speaker or surrounding interior trim is found to be loose or improperly secured, correctly secure the item.

When equipped with an amplifier, it is possible for some individual circuit faults to affect more than one speakers operation. Perform diagnostic tests in the sequence listed to avoid misdiagnosis.

The amplifier control circuit will measure less than 1 V when the mute function is OFF, and approximately 8 V DC when at full mute. When mute is active, the radio stops sending the varying AC voltage to the amplifier/speakers.

Reference Information

Schematic Reference

Radio/Navigation System Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Radio/Audio System Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information Special Tools

EL-50334-50 USB Cable and Adapter Kit

Circuit/System Verification

Without Amplifier

Radio ON, Mute OFF, verify clear audio is heard from each audio speaker.

If audio is inoperative from all speakers, replace the radio.

If audio is inoperative from one or more, but not all, speakers or the audio emitted from the speakers is not clear, refer to Speaker Circuit Malfunction - without Amplifier.

With Amplifier

Radio ON, Mute OFF, verify clear audio is heard from each audio speaker.

If audio is not heard from all speakers, or the audio emitted from the speakers is not clear, refer to Speaker Circuit Malfunction- with Amplifier.

Circuit/System Testing

Speaker Malfunction - without Amplifier

NOTE: In the following tests, audio signal frequencies (Hz) will be tested. To prevent misdiagnosis, the door chime must be OFF during testing. Ensure the driver door latch is closed during testing.

1. Vehicle OFF, disconnect the harness connector at the appropriate P19 Speaker. Vehicle in Service Mode, radio ON, mute OFF.

2. Test for 5 - 7 V between each audio signal circuit terminal 1 and terminal 2 and ground.

If less than 5 V

1. Vehicle OFF, disconnect the X1 harness connector at the A11 Radio.

2. Test for infinite resistance between the signal circuit and ground.

If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance

3. Test for less than 2 Ω in the signal circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit. If less than 2 Ω, replace the A11 Radio.

If greater than 7 V

1. Vehicle OFF, disconnect the X1 harness connector at the A11 Radio. Vehicle in Service Mode.

2. Test for less than 1 V between the signal circuit and ground.

If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V, replace the A11 Radio.

If between 5 - 7 V

3. Insert the EL-50334-6 Audio Test CD from the EL-50334-50 USB cable and adapter kit. Play track number three (50 Hz bass test tone) from the test CD.

4. Test for 49 - 51 Hz AC between each signal circuit terminal 1 and terminal 2 and ground.

If not between 49 - 51 Hz AC

Replace the A11 Radio.

If between 49 - 51 Hz AC

5. Test or replace the P19 Speaker.

Speaker Malfunction- with Amplifier

1. Vehicle OFF, disconnect the X1 harness connector at the T3 Audio Amplifier.

2. Test for less than 10 Ω between the ground circuit terminal 8 and ground.

If 10 Ω or greater

1. Vehicle OFF.

2. Test for less than 2 Ω in the ground circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit.

If less than 2 Ω, repair the open/high resistance in the ground connection.

If less than 10 Ω

3. Verify that a test lamp illuminates between the B+ circuit terminal 4 and ground.

If the test lamp does not illuminate and the circuit fuse is good

1. Vehicle OFF.

2. Test for less than 2 Ω in the B+ circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit. If less than 2 Ω, refer to Power Mode Mismatch .

If the test lamp does not illuminate and the circuit fuse is open

1. Vehicle OFF.

2. Test for infinite resistance between the B+ circuit and ground.

If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance, replace the T3 Audio Amplifier.

If the test lamp illuminates

4. Disconnect the X2 harness connector at the T3 Audio Amplifier.

5. Verify a test lamp does not illuminate between the control circuit terminal 14 and ground.

If the test lamp illuminates

1. Disconnect the X1 harness at the A11 Radio.

2. Verify a test lamp does not illuminate between the control circuit and ground. If the test lamp illuminates, repair the short to voltage on the circuit.

If the test lamp does not illuminate, replace the A11 Radio.

If the test lamp does not illuminate

6. Vehicle in Service Mode, A11 Radio ON.

7. Verify a test lamp illuminates between the control circuit terminal 14 and ground.

If the test lamp does not illuminate

1. Vehicle OFF. Disconnect the X1 harness at the A11 Radio.

2. Test for less than 2 Ω in the control circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit. If less than 2 Ω, replace the A11 Radio.

If the test lamp illuminates

8. Radio ON, mute ON.

9. Test for 7.5 - 8.5 V between the control circuit terminal 12 and ground.

If greater than 8.5 V

1. Vehicle OFF, disconnect the X1 harness connector at the A11 Radio. Vehicle in Service Mode.

2. Test for less than 1 V between the control circuit and ground.

If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V, replace the A11 Radio.

If less than 7.5 V

1. Vehicle OFF, disconnect the X1 harness connector at the A11 Radio.

2. Test for infinite resistance between the control circuit and ground.

If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance

3. Test for less than 2 Ω in the signal circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit. If less than 2 Ω, replace the A11 Radio.

If between 7.5 - 8.5 V

10. Radio ON, mute OFF.

11. Test for less than 1 V between the control circuit terminal 12 and ground.

If greater than 1 V

Replace the A11 Radio.

If less than 1 V

12. Vehicle OFF, disconnect the X3 harness connector at the T3 Audio Amplifier.

13. Vehicle in Service Mode, A11 Radio ON.

14. Test for 5 - 7 V between the signal circuit terminals listed below and ground: Left front low level audio signal (+) terminal 14

Left front low level audio signal (-) terminal 6

Right front low level audio signal (+) terminal 5 Right front low level audio signal (-) terminal 13 Left rear low level audio signal (+) terminal 12

Left rear low level audio signal (-) terminal 4

Right rear low level audio signal (+) terminal 3 Right rear low level audio signal (-) terminal 11 If less than 5 V

1. Vehicle OFF, disconnect the X1 harness connector at the A11 Radio.

2. Test for infinite resistance between the signal circuit and ground.

If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance

3. Test for less than 2 Ω in the signal circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit. If less than 2 Ω, replace the A11 Radio.

If greater than 7 V

1. Vehicle OFF, disconnect the X1 harness connector at the A11 Radio. Vehicle in Service Mode.

2. Test for less than 1 V between the signal circuit and ground.

If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V, replace the A11 Radio.

If between 5 - 7 V

15. Insert the EL - 50334 - 6 Audio Test CD from the EL-50334-50 USB cable and adapter kit. Play track number three (50 Hz bass test tone) from the test CD.

16. Test for 49 - 51 Hz AC between the audio signal circuit terminals listed below and ground: Left front low level audio signal (+) terminal 14

Left front low level audio signal (-) terminal 6

Right front low level audio signal (+) terminal 5 Right front low level audio signal (-) terminal 13 Left rear low level audio signal (+) terminal 12

Left rear low level audio signal (-) terminal 4

Right rear low level audio signal (+) terminal 3 Right rear low level audio signal (-) terminal 11 If not between 49 - 51 Hz AC

Replace the A11 Radio.

If between 49 - 51 Hz AC

17. Vehicle OFF, connect all harness connectors.

18. Disconnect the harness connector at the appropriate P19 Speaker. Vehicle in Service Mode, A11 Radio ON.

19. Test for 5 - 7 V between the appropriate signal circuit terminals listed below and ground: Door speaker or tweeter speaker signal (+): terminal 2

Door speaker or tweeter speaker signal (-): terminal 1 Subwoofer speaker signal (+) terminal B

Subwoofer speaker signal (-) terminal A

If less than 5 V

1. Vehicle OFF, disconnect the X3 harness connector at the T3 Audio Amplifier.

2. Test for infinite resistance between the signal circuit and ground.

If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance

3. Test for less than 2 Ω in the signal circuit end to end.

If 2 Ω or greater, repair the open/high resistance in the circuit. If less than 2 Ω, replace the T3 Audio Amplifier.

If greater than 7 V

1. Vehicle OFF, disconnect the X3 harness connector at the T3 Audio Amplifier. Vehicle in Service Mode.

2. Test for less than 1 V between the signal circuit and ground.

If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V, replace the T3 Audio Amplifier.

If between 5 - 7 V

NOTE: In the following tests, audio signal frequencies (Hz) will be tested. To prevent misdiagnosis, the door chime must be OFF during testing. Ensure the driver door latch is closed during testing.

20. Mute OFF, play track number three (50 Hz bass test tone) from the test CD.

21. Test for 49 - 51 Hz AC between the appropriate signal circuit terminals listed below and ground: Door speaker or tweeter speaker signal (+): terminal 2

Door speaker or tweeter speaker signal (-): terminal 1 Subwoofer speaker signal (+) terminal B

Subwoofer speaker signal (-) terminal A

If not between 49 - 51 Hz AC

Replace the T3 Audio Amplifier.

If between 49 - 51 Hz AC

22. Test or replace the P19 Speaker.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Speaker Replacement Reference

Refer to Control Module References for amplifier or radio replacement, programming and setup

UNABLE TO CONTACT ONSTAR CALL CENTER

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Refer to Diagnostic Procedure Instructions to provide an overview of each diagnostic category.

DTC Descriptors

DTC B2470 02

Cellular Phone Antenna Circuit Malfunction Short to Ground

DTC B2470 04

Cellular Phone Antenna Circuit Malfunction Open Circuit

Circuit/System Description

The primary cellular phone antenna element is connected to the telematics communication interface control module (violet connector) via a shielded coaxial cable. Cellular communication takes place on both the primary cellular antenna signal circuit and the GPS/secondary cellular antenna signal circuit. This diagnostic only applies to the primary cellular antenna signal circuit. Internal to the antenna on the cellular antenna signal circuit resistance is used to apply a load, which the telematics communication interface control module uses to detect the presence of the antenna.

Conditions for Running the DTC

Ignition in the RUN or ACC position.

System voltage is between 9.5 V and 15.5 V.

The above conditions are present for greater than 1 s.

Conditions for Setting the DTC

B2470 02

The telematics communication interface control module detects a short to ground on the primary cellular antenna signal circuit.

B2470 04

The telematics communication interface control module detects an open or high resistance on the primary cellular antenna signal circuit.

The above conditions are present for greater than 1 s.

Action Taken When the DTC Sets

The OnStar® status LED turns red.

Conditions for Clearing the DTC

The telematics communication interface control module detects the presence of a cellular antenna.

A history DTC clears after 50 malfunction-free ignition cycles.

Reference Information

Schematic Reference

OnStar/Telematics Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

OnStar Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information Special Tools

EL-49903-1 Test Antenna Navn-Cell Comn

Circuit/System Testing

NOTE: The vehicle may be equipped with sectioned coax. Test each section and replace only the faulty section, not the entire length of coax.

The following verification requires the vehicle to be outside with an unobstructed view of the southern sky. Allow 5 min after turning the ignition ON for the GPS satellites to acquire vehicle signal.

1. Ignition OFF/Vehicle OFF and all vehicle systems OFF, disconnect the violet primary cellular coax cable connector at the K73 Telematics Communication Interface Control Module. It may take up to 2 min for all vehicle systems to power down.

2. Using the EL-49903-1 Test Antenna Navn-Cell Comn connect the violet coax cable to the K73 Telematics Communication Interface Control Module. Place the test antenna on the roof of the vehicle, ignition ON/vehicle in Service Mode.

3. Verify the DTC does not set or a call can be completed to the OnStar Call Center while operating the vehicle within the conditions for running the DTC.

If the DTC sets or a call can not be completed to the OnStar Call Center

Replace the K73 Telematics Communications Interface Control Module.

If the DTC does not set or a call can be completed to the OnStar Call Center

4. Ignition OFF/Vehicle OFF.

5. Disconnect the EL-49903-1 Test Antenna Navn-Cell Comn from the K73 Telematics Communication Interface Control Module

6. Test the coax cable. Refer to Component Testing.

If the coax cable does not pass the test

Replace the coax cable.

If the coax cable passes the test

7. Test or replace the T2RR Antenna - Roof Rear.

Component Testing

CAUTION: Refer to Test Probe Caution

NOTE: Before testing the coax cable, check the cable exterior for being pinched, cut, damaged, or having loose connections at the components, which can cause reception issues.

To prevent false readings when testing the center coax terminals, use care not to ground the test probe on the outer housing/shield.

Coax Cable Test

1. Test for less than 5 Ω between the coax cable center terminal end to end.

If 5 Ω or greater

Replace the coax cable.

If less than 5 Ω

2. Test for greater than 5 Ω between the coax cable outer shield end to end.

If 5 Ω or greater

Replace the coax cable.

If less than 5 Ω

3. Test for infinite resistance between the coax cable center terminal and the coax cable outer shield.

If less than infinite resistance

Replace the coax cable.

If infinite resistance

4. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair procedure.

Refer to High Frequency Antenna Replacement

Refer to Control Module References for telematics communication interface control module replacement, setup, and programming

ONSTAR VOICE RECOGNITION MALFUNCTION

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Refer to Diagnostic Procedure Instructions to provide an overview of each diagnostic category.

Circuit/System Description

The telematics communication interface control module is capable of interpreting voice commands received over the cellular microphone circuits. Speech recognition allows the user to speak to one computer in the vehicle, and one reached over the cellular communication network. The module attempts to understand the users command, and responds by speaking back, or by taking the appropriate action, e.g. dialing the phone.

Reference Information

Schematic Reference

OnStar/Telematics Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

OnStar Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

Circuit/System Verification

NOTE: It is necessary to have the vehicle in an open outside area where a cellular call can be successfully placed and GPS data can be received from satellites.

The vehicle should be located in a quiet area.

1. Vehicle in Service Mode.

2. Verify that your voice is heard clearly by the OnStar Call center.

If your voice can not be heard clearly

Refer to OnStar Microphone Malfunction

If your voice can be heard clearly

3. Verify that the system responds appropriately to all voice commands by pressing the voice command button and attempting to operate the system using multiple voice commands.

If the OnStar system does not respond to any voice commands

Replace the K73 Telematics Communication Interface Control Module

If the OnStar system responds to some, but not all voice commands

Refer to OnStar Description and Operation for tips on proper pronunciation

If the OnStar system responds to all voice commands

4. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair procedure.

Refer to Control Module References for telematics communication interface control module replacement, programming and setup

VOICE RECOGNITION MALFUNCTION

Diagnostic Instructions

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Review Strategy Based Diagnosis for an overview of the diagnostic approach.

Refer to Diagnostic Procedure Instructions to provide an overview of each diagnostic category.

Diagnostic Fault Information