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Data Communications - Diagnostic Information and Procedures - Volt

DIAGNOSTIC INFORMATION AND PROCEDURES

CONTROL MODULE U CODE LIST

This list includes all Data Communications related U-code DTCs in alphanumeric order with descriptors for all devices. Not all DTCs listed will be applicable to all vehicles.

For symptom byte information, refer to Symptom Byte List .

DTC B1000: ELECTRONIC CONTROL UNIT

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.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC B1000

Electronic Control Unit

For symptom byte information, refer to Symptom Byte List .

Circuit/System Description

The internal fault detection is handled inside the device. The symptom byte information is for engineering reference only. No external circuit diagnosis is involved.

Conditions for Running the DTC

The device runs the program to detect an internal fault when power up is commanded. The only requirements are voltage and ground. This program runs even if the voltage is out of the valid operating range.

Conditions for Setting the DTC

The device has detected an internal malfunction.

Action Taken When the DTC Sets

The device refuses all additional inputs.

Conditions for Clearing the DTC

A current DTC clears when the malfunction is no longer present.

A history DTC clears when the device ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.

Diagnostic Aids

This DTC may be stored as a history DTC without affecting the operation of the device.

If stored only as a history DTC and not retrieved as a current DTC, do not replace the device.

If this DTC is retrieved as both a current and history DTC, replace the device that set the DTC.

Reference Information

Schematic Reference

Data Communication Schematics Control Module References

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Data Link Communications 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 B1000 is not set.

If DTC B1000 is set

Replace the device that set the DTC.

If DTC B1000 is not set

3. All OK

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for device replacement, programming and setup

DTC B1001: OPTION CONFIGURATION

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.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC B1001

Option Configuration

For symptom byte information, refer to Symptom Byte List .

Circuit/System Description

Some devices must be configured with serial numbers, vehicle options, or other information. If a device was not properly configured after installation that device may set DTC B1001. The symptom byte information is for engineering reference only. No external circuit diagnosis is involved.

Conditions for Running the DTC

Battery voltage is between 9 - 16 V and data link communications operate normally.

Conditions for Setting the DTC

The device is not configured properly.

Conditions for Clearing the DTC

A current DTC clears when the malfunction is no longer present.

A history DTC clears when the device ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

Reference Information

Schematic Reference

Data Communication Schematics Control Module References

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Data Link Communications 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 B1001 is not set.

If DTC B1001 is set

1. Program the device that set the DTC.

2. Verify the DTC does not set.

If the DTC sets, replace the device that set the DTC. If the DTC does not set

3. All OK.

If DTC B1001 is not set

3. All OK

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for device replacement, programming and setup

DTC B1016: VEHICLE IDENTIFICATION NUMBER INFORMATION NOT PROGRAMMED

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.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC B1016

Vehicle Identification Number Information Not Programmed For symptom byte information, refer to Symptom Byte List .

Circuit/System Description

The device performs a self test and vehicle identification number (VIN) verification. This DTC indicates that a VIN is not programmed or that the device has an internal fault. The internal fault detection is handled inside the device, no external circuits are involved.

Conditions for Running the DTC

The only requirements are voltage and ground.

Conditions for Setting the DTC

The device has detected that the VIN is not programmed.

Conditions for Clearing the DTC

The condition for setting the DTC is no longer present.

The history DTC will clear after 50 fault-free ignition cycles. The DTC can be cleared using a scan tool.

Reference Information

Schematic Reference

Data Communication Schematics Control Module References

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Data Link Communications 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 B1016 is not set.

If DTC B1016 is set

1. Program the device that set the DTC.

2. Verify the DTC does not set.

If the DTC sets, replace the device that set the DTC. If the DTC does not set

3. All OK.

If DTC B1016 is not set

3. All OK

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for device replacement, programming and setup

DTC B101D: ELECTRONIC CONTROL UNIT HARDWARE

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.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC B101D

Electronic Control Unit Hardware

For symptom byte information, refer to Symptom Byte List .

Circuit/System Description

The internal fault detection is handled inside the device. The symptom byte information is for engineering reference only. No external circuit diagnosis is involved.

Conditions for Running the DTC

The device runs the program to detect an internal fault when power up is commanded. The only requirements are voltage and ground. This program runs even if the voltage is out of the valid operating range.

The keyless entry control module will set this DTC with symptom byte 39 when the keyless entry control module antenna is activated.

Conditions for Setting the DTC

The device has detected an internal malfunction.

Action Taken When the DTC Sets

The device refuses all additional inputs.

Conditions for Clearing the DTC

A current DTC clears when the malfunction is no longer present.

A history DTC clears when the device ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.

Diagnostic Aids

This DTC may be stored as a history DTC without affecting the operation of the device.

Do not replace a device based only on DTC B101D being set in history with the exception of the following devices:

K36 Inflatable Restraint Sensing and Diagnostic Module K85 Passenger Presence Module

If DTC B101D is set as current, replace the appropriate device.

Reference Information

Schematic Reference

Data Communication Schematics Control Module References

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Data Link Communications 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 B101D is not set.

If DTC B101D is set with symptom byte 43

1. Program the device that set the DTC.

2. Verify the DTC does not set.

If the DTC sets, replace the device that set the DTC. If the DTC does not set

3. All OK.

If DTC B101D is set with any symptom byte, except symptom byte 43

Replace the device that set the DTC.

If DTC B101D is not set

3. All OK

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for device replacement, programming and setup

DTC B101E: ELECTRONIC CONTROL UNIT SOFTWARE

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.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC B101E

Electronic Control Unit Software

For symptom byte information, refer to Symptom Byte List .

Circuit/System Description

Some devices must be configured with specific software, serial numbers, vehicle options, or other information. If a device was not properly configured after installation that device may set DTC B101E. The symptom byte information is for engineering reference only. No external circuit diagnosis is involved.

Conditions for Running the DTC

Battery voltage is between 9 - 16 V and data link communications operate normally.

Conditions for Setting the DTC

The device is not configured properly.

Conditions for Clearing the DTC

A current DTC clears when the malfunction is no longer present.

A history DTC clears when the device ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

Reference Information

Schematic Reference

Data Communication Schematics Control Module References

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Data Link Communications 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 B101E is not set.

If DTC B101E is set

1. Program the device that set the DTC.

2. Verify the DTC does not set.

If the DTC sets, replace the device that set the DTC. If the DTC does not set

3. All OK.

If DTC B101E is not set

3. All OK

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for device replacement, programming and setup

DTC C056D: ELECTRONIC CONTROL UNIT HARDWARE

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.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC C056D

Electronic Control Unit Hardware

For symptom byte information, refer to Symptom Byte List .

Circuit/System Description

The internal fault detection is handled inside the device. The symptom byte information is for engineering reference only. No external circuit diagnosis is involved.

Conditions for Running the DTC

The device runs the program to detect an internal fault when power up is commanded. The only requirements are voltage and ground. This program runs even if the voltage is out of the valid operating range.

Conditions for Setting the DTC

The device has detected an internal malfunction.

Action Taken When the DTC Sets

The device refuses all additional inputs.

Conditions for Clearing the DTC

A current DTC clears when the malfunction is no longer present.

A history DTC clears when the device ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.

Diagnostic Aids

This DTC may be stored as a history DTC without affecting the operation of the device.

If stored only as a history DTC and not retrieved as a current DTC, do not replace the device.

If this DTC is retrieved as both a current and history DTC, replace the device that set the DTC.

Reference Information

Schematic Reference

Data Communication Schematics Control Module References

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Data Link Communications 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 C056D is not set.

If DTC C056D is set in a device that can be programmed

1. Program the device that set the DTC.

2. Verify the DTC does not set.

If the DTC sets, replace the device that set the DTC. If the DTC does not set

3. All OK.

If DTC C056D is set in a device that cannot be programmed

Replace the device that set the DTC.

If DTC C056D is not set

3. All OK

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for device replacement, programming and setup

DTC C056E: ELECTRONIC CONTROL UNIT SOFTWARE

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.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC C056E

Electronic Control Unit Software

For symptom byte information, refer to Symptom Byte List .

Circuit/System Description

Some devices must be configured with specific software, serial numbers, vehicle options, or other information. If a device was not properly configured after installation that device may set DTC C056E. The symptom byte information is for engineering reference only. No external circuit diagnosis is involved.

Conditions for Running the DTC

Battery voltage is between 9 - 16 V and data link communications operate normally.

Conditions for Setting the DTC

The device is not configured properly.

Conditions for Clearing the DTC

A current DTC clears when the malfunction is no longer present.

A history DTC clears when the device ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

Reference Information

Schematic Reference

Data Communication Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Data Link Communications Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

Scan Tool References

Control Module References for scan tool information

Circuit/System Verification

1. Vehicle in Service Mode.

2. Verify DTC C056E is not set.

If DTC C056E is set

1. Program the device that set the DTC.

2. Verify the DTC does not set.

If the DTC sets, replace the device that set the DTC. If the DTC does not set

3. All OK.

If DTC C056E is not set

3. All OK

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for device replacement, programming and setup

DTC P0601-P0607, P060A-P060C, P062F, P16E9-P16F0, OR P262B: CONTROL MODULE

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.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P0601

Control Module Read Only Memory Performance

DTC P0602

Control Module Not Programmed

DTC P0603

Control Module Long Term Memory Reset

DTC P0604

Control Module Random Access Memory Performance

DTC P0605

Control Module Programming Read Only Memory Performance

DTC P0606

Control Module Processor Performance

DTC P0607

Control Module Performance

DTC P060A

Control Module Monitoring Processor Performance

DTC P060B

Control Module Analog to Digital Converter Performance

DTC P060C

Control Module Main Processor Performance

DTC P062F

Control Module Long Term Memory Performance

DTC P16E9

Control Module Serial Peripheral Interface Bus 2

DTC P16EA

Control Module Serial Peripheral Interface Bus 3

DTC P16EB

Control Module Serial Peripheral Interface Bus 4

DTC P16EC

Control Module Serial Peripheral Interface Bus 5

DTC P16ED

Control Module Serial Peripheral Interface Bus 6

DTC P16EE

Control Module Serial Peripheral Interface Bus 7

DTC P16EF

Control Module Serial Peripheral Interface Bus 8

DTC P16F0

Control Module Serial Peripheral Interface Bus 1

DTC P262B

Control Module Power Off Timer Performance

For symptom byte information, refer to Symptom Byte List .

Circuit/System Description

This diagnostic applies to internal microprocessor integrity conditions within the device. This diagnostic also addresses if the device is not programmed. The device monitors its ability to read and write to the memory. It also monitors a timing function. No external circuits are involved.

Conditions for Running the DTC

Vehicle ON.

The system voltage is greater than 9.5 V.

Conditions for Setting the DTC

The device detects an internal malfunction or incomplete programming.

Action Taken When the DTC Sets

DTCs P0601 - P0607, P060A - P060C, and P16E9 - P16F0 are Type A DTCs.

DTC P062F is a Type C DTCs. DTC P262B is a Type B DTC.

The high voltage contactor relays may open.

Conditions for Clearing the DTC

DTCs P0601 - P0607, P060A - P060C, and P16E9 - P16F0 are Type A DTCs.

DTC P062F is a Type C DTCs. DTC P262B is a Type B DTC.

Diagnostic Aids

The DTC P0606 may set in Hybrid/EV Powertrain Control Module 2 due to other faults. Do not replace the Hybrid/EV Powertrain Control Module 2 until other DTCs are diagnosed first.

The DTC P0606 can falsely set in Hybrid/EV Powertrain Control Module 2 when the 12 V battery has been disconnected/re-connected or if the 12 V battery has been overcharged (over 18 V). In this case, do the following. If this DTC becomes history, use scan tool to clear this DTC. No further action is required:

Vehicle OFF and all vehicle systems off. It may take up to 2 minutes for all vehicle systems to power down.

Vehicle ON, verify that DTC P0606 is in history and contactors close. (If DTC P0606 remains current and contactors do not close, repeat the above step again).

Use scan tool to clear the DTC to turn off the malfunction indicator lamp (MIL).

If stored only as a history DTC and not retrieved as a current DTC, do not replace the device.

Reference Information

Schematic Reference

Data Communication Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Data Link Communications Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool References

Control Module References for scan tool information

Circuit/System Verification

NOTE: The DTC P0606 can falsely set in K114B Hybrid/EV Powertrain Control Module 2 when disconnecting the 12 V battery. See Diagnostic Aids section for more information.

1. Vehicle in Service Mode.

2. Verify DTC P0606 is not set.

If DTC P0606 is set with other DTCs set

Diagnose all other DTCs first. Refer to Diagnostic Trouble Code (DTC) List - Vehicle .

If DTC P0606 is set without other DTCs set

Replace the device that set the DTC.

If DTC P0606 is not set

3. Verify DTC P0602 is not set.

If DTC P0602 is set

1. Program the device that set the DTC.

2. Verify the DTC does not set.

If the DTC sets, replace the device that set the DTC.

If the DTC does not set

3. All OK.

If DTC P0602 is not set

4. Verify DTC P0601, P0603, P0604, P0605, P0607, P060A, P060B, P060C, P062F, P16E9, P16EA, P16EB, P16EC, P16ED, P16EE, P16EF, P16F0, or P262B is not set.

If any of the DTCs are set

Replace the device that set the DTC.

If none of the DTCs are set

5. All OK

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for device replacement, programming and setup

DTC P06E4: CONTROL MODULE WAKE-UP CIRCUIT PERFORMANCE (HYBRID/EV POWERTRAIN CONTROL MODULE 2)

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.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P06E4

Control Module Wake-Up Circuit Performance

For symptom byte information, refer to Symptom Byte List .

Diagnostic Fault Information

Circuit/System Description

The accessory wake up serial data 2 circuit is energized by the K114B Hybrid/EV Powertrain Control Module 2 to immediately activate other devices connected to this circuit when the K9 Body Control Module signals the K114B Hybrid/EV Powertrain Control Module 2 that serial data is required.

Depending on the option content, devices that may receive the wake up signal are as follows:

K1 14 V Power Module T18 Battery Charger

K16 Battery Energy Control Module

K17 Electronic Brake Control Module G1 A/C Compressor

K71 Transmission Control Module / T12 Automatic Transmission Assembly K20 Engine Control Module

K114A Hybrid/EV Powertrain Control Module 1 / T6 Power Inverter Module

Conditions for Running the DTC

The system voltage is between 9 - 16 V.

The vehicle power mode master requires serial data communication to occur.

The K114B Hybrid/EV Powertrain Control Module 2 attempts to wake up the devices connected to its control module output wake up circuit.

Circuit check runs continuously.

Conditions for Setting the DTC

The K114B Hybrid/EV Powertrain Control Module 2 detects a fault in the control module output wake up circuit.

A circuit fault exists for greater than 6 s.

Action Taken When the DTC Sets

The DTC P06E4 is a type A DTC.

The devices is never signaled. Therefore, the specific subsystems will not function. The vehicle will not start while the circuit is shorted to ground.

The malfunction indicator lamp (MIL) will illuminate, along with several DIC messages.

Conditions for Clearing the DTC

The DTC P06E4 is a type A DTC.

A current DTC clears when the malfunction is no longer present.

A history DTC clears when the device ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.

Diagnostic Aids

Short to ground will also set multiple no communication codes for high speed GMLAN devices.

Reference Information

Schematic Reference

Data Communication Schematics Control Module References

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Data Link Communications 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-48900 HEV Safety Kit

For equivalent regional tools, refer to Special Tools .

Circuit/System Verification

1. Verify that DTC U0073, U0074, U0077, U0078, U007A, U1814, U2099, B097B, B1325, B1330, B1370, B1380, B1424, B1428, B1440, B1441, B1451, B1517, C0800, C0899, C12E1, P0560, or P0562 is not

set.

If any of the DTCs are set

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

If none of the DTCs are set

2. Refer to Circuit/System Testing.

Circuit/System Testing

WARNING: Always perform the High Voltage Disabling procedure prior to servicing any High Voltage component or connection. Personal Protection Equipment (PPE) and proper procedures must be followed.

The High Voltage Disabling procedure includes the following steps: Identify how to disable high voltage.

Identify how to test for the presence of high voltage.

Identify condition under which high voltage is always present and personal protection equipment (PPE) and proper procedures must be followed.

Before working on any high voltage system, be sure to wear the following Personal Protection Equipment:

Safety glasses with appropriate side shields when within 15 meters (50 feet) of the vehicle, either indoors or outdoors.

Certified and up-to-date Class "0" Insulation gloves rated at 1000V with leather protectors.

Visually and functionally inspect the gloves before use.

Wear the Insulation gloves with leather protectors at all times when working with the high voltage battery assembly, whether the system is energized or not.

Failure to follow the procedures may result in serious injury or death.

NOTE: Use the schematic to determine which devices are on the K114B Hybrid/EV Powertrain Control Module 2 terminal 69 X2 accessory wake up serial data 2 circuit. Use the connector end view to identify the B+, ignition, and accessory wake up serial data 2 circuit terminals for each of those devices.

1. Vehicle OFF, disconnect the X2 harness connector at the K114B Hybrid/EV Powertrain Control Module 2.

2. Vehicle in Service Mode.

3. Verify that a test lamp illuminates between the accessory wake up serial data circuit terminal 67 X2 and ground.

If the test lamp does not illuminate

1. Vehicle OFF and all vehicle systems OFF, remove the test lamp, disconnect the X4 harness connector at the K9 Body Control Module.

2. Test for greater than 100 Ω between the K114B Hybrid/EV Powertrain Control Module 2 wake up circuit terminal 67 X2 and ground.

If 100 Ω or less, repair the short to ground in the accessory wake up serial data circuit. If greater than 100 Ω

3. Test for less than 2 Ω between the K114B Hybrid/EV Powertrain Control Module 2 wake up circuit terminal 67 X2 and the K9 Body Control Module wake up circuit terminal 22 X4.

If 2 Ω or greater, repair the open/high resistance in the accessory wake up serial data circuit. If less than 2 Ω

4. Replace the K9 Body Control Module.

If the test lamp illuminates

4. Vehicle OFF, remove the test lamp, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. It may take up to 2 min for all vehicle systems to power down.

5. Test for greater than 100 Ω, but less than infinite resistance, between the accessory wake up serial data 2 circuit terminal 69 X2 and ground.

If 100 Ω or less

Refer to Testing the Accessory Wake Up Serial Data 2 Circuits for a Short to Ground.

If infinite resistance

Test for an open/high resistance in the accessory wake up serial data 2 circuit.

If greater than 100 Ω and less than infinite resistance

6. Vehicle in Service Mode.

7. Verify that a test lamp illuminates between each B+ circuit terminal and ground.

If the test lamp does not illuminate and the circuit fuse is good

1. Vehicle 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 less than 2 Ω, verify the fuse is not open and there is voltage at the fuse.

If the test lamp does not illuminate and the circuit fuse is open

1. Vehicle OFF, remove the test lamp.

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 K114B Hybrid/EV Powertrain Control Module 2.

If the test lamp illuminates

8. Vehicle in Service Mode.

9. Verify that a test lamp illuminates between each ignition circuit terminal and ground.

If the test lamp does not illuminate and the circuit fuse is good

1. Vehicle OFF, remove the test lamp.

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

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

If less than 2 Ω, verify the fuse is OK and there is voltage at the fuse.

If the test lamp does not illuminate and the circuit fuse is open

1. Vehicle OFF, remove the test lamp.

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

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

If infinite resistance, replace the K114B Hybrid/EV Powertrain Control Module 2.

If the test lamp illuminates

10. Replace the K114B Hybrid/EV Powertrain Control Module 2.

Testing the Accessory Wake Up Serial Data 2 Circuits for a Short to Ground

1. Perform the High Voltage Disabling procedure before proceeding with this diagnostic. Refer to High Voltage Disabling .

2. Reconnect the 12 V battery.

3. Vehicle OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. Disconnect the harness connectors at an easily accessible device that shares the K114B Hybrid/EV Powertrain Control Module 2 terminal 69 X2 accessory wake up serial data 2 circuit. It may

take up to 2 min for all vehicle systems to power down.

4. Test for less than 100 Ω between the K114B Hybrid/EV Powertrain Control Module 2 accessory wake up serial data 2 circuit terminal 69 X2 and ground.

If 100 Ω or greater

Replace the device that was just disconnected.

If less than 100 Ω

5. Repeat step 3 until all devices on the K114B Hybrid/EV Powertrain Control Module 2 accessory wake up serial data 2 circuit terminal 69 X2 have been disconnected.

6. Repair the short to ground on the accessory wake up serial data 2 circuit.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for device replacement, programming and setup.

DTC P0A1F, P1A01, P1A05, OR P1A06: BATTERY ENERGY CONTROL MODULE

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.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P0A1F

Battery Energy Control Module Performance

DTC P1A01

Battery Energy Control Module Long Term Memory Performance

DTC P1A05

Battery Energy Control Module Random Access Memory

DTC P1A06

Battery Energy Control Module Read Only Memory For symptom byte information, refer to Symptom Byte List . Circuit/System Description

The Battery Energy Control Module will diagnose its own systems and determine when a fault condition is present. Diagnostics and system status is communicated from the Battery Energy Control Module to the Hybrid/EV Powertrain Control Module 2 through serial data. The Hybrid/EV Powertrain Control Module 2 is

the host controller for diagnostic trouble code (DTC) information.

This diagnostic applies to internal microprocessor integrity conditions within the Battery Energy Control Module. This fault is internal to the Battery Energy Control Module and no external circuits are involved.

Conditions for Running the DTC

The Battery Energy Control Module is awake and communicating. The system voltage is at least 9 V.

Conditions for Setting the DTC

The Battery Energy Control Module has detected an internal malfunction.

Action Taken When the DTC Sets

DTCs P0A1F, P1A01, P1A05, and P1A06 are type A DTCs.

Vehicle goes to reduced battery power mode. After vehicle is turned off, vehicle will not return to propulsion active mode.

Conditions for Clearing the DTC

DTCs P0A1F, P1A01, P1A05, and P1A06 are type A DTCs.

Diagnostic Aids

If stored only as a history DTC and not retrieved as a current DTC, do not replace the device.

Reference Information

Schematic Reference

Data Communication Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Data Link Communications Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool References

Control Module References for scan tool information

Circuit/System Verification

WARNING: Always perform the High Voltage Disabling procedure prior to servicing any High Voltage component or connection. Personal Protection Equipment (PPE) and proper procedures must be followed.

The High Voltage Disabling procedure includes the following steps: Identify how to disable high voltage.

Identify how to test for the presence of high voltage.

Identify condition under which high voltage is always present and personal protection equipment (PPE) and proper procedures must be followed.

Before working on any high voltage system, be sure to wear the following Personal Protection Equipment:

Safety glasses with appropriate side shields when within 15 meters (50 feet) of the vehicle, either indoors or outdoors.

Certified and up-to-date Class "0" Insulation gloves rated at 1000V with leather protectors.

Visually and functionally inspect the gloves before use.

Wear the Insulation gloves with leather protectors at all times when working with the high voltage battery assembly, whether the system is energized or not.

Failure to follow the procedures may result in serious injury or death.

1. Vehicle in Service Mode.

NOTE: If the power is interrupted at exactly the time the K16 Battery Energy Control Module is writing to its memory, it may set a false P1A01 DTC.

2. Verify that DTC P1A01 is not set.

If DTC P1A01 is set

1. Vehicle OFF and all vehicle systems OFF. It may take up to 2 min for all vehicle systems to power down.

2. Vehicle in Service Mode.

3. Verify that the DTC does not set.

If the DTC sets, replace the K16 Battery Energy Control Module. If the DTC does not set

4. All OK.

If DTC P1A01 is not set

3. Verify that DTC P0A1F, P1A05, or P1A06 is not set.

If any of the DTCs are set

Replace the K16 Battery Energy Control Module.

If none of the DTCs are set

4. All OK

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for device replacement, programming and setup

DTC P16B7: ELECTRIC A/C COMPRESSOR CONTROL MODULE WAKE-UP CIRCUIT 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.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P16B7

Electric A/C Compressor Control Module Wake-Up Circuit Performance For symptom byte information, refer to Symptom Byte List .

Diagnostic Fault Information

Circuit/System Description

The accessory wake up serial data 2 circuit is energized by the K114B Hybrid/EV Powertrain Control Module 2 to immediately activate the G1 A/C Compressor connected to this circuit when the body control module signals the K114B Hybrid/EV Powertrain Control Module 2 that serial data is required.

Conditions for Running the DTC

The system voltage is greater than 10.25 V. The G1 A/C Compressor is awake.

Vehicle ON.

The G1 A/C Compressor receives serial data message from K114B Hybrid/EV Powertrain Control Module 2 and "Propulsion System Active" is TRUE for 500 ms continuously.

Conditions for Setting the DTC

The G1 A/C Compressor detects a fault in the wake up circuit.

Action Taken When the DTC Sets DTC P16B7 is a type B DTC. Conditions for Clearing the DTC DTC P16B7 is a type B DTC. Diagnostic Aids

Short to ground may set multiple no communication codes for high speed GMLAN devices.

Reference Information

Schematic Reference

Data Communication Schematics Control Module References

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Data Link Communications 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 P06E4 is not set.

If DTC P06E4 is set

Refer to DTC P06E4 (Hybrid/EV Powertrain Control Module 2).

If DTC P06E4 is not set

3. Refer to Circuit/System Testing.

Circuit/System Testing

NOTE: Use the schematics and connector end views to identify the device's accessory wake up serial data 2 circuit terminals.

1. Vehicle OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. Disconnect the X1 harness connector at the G1 A/C Compressor. It may take up to 2 min for all vehicle systems to power down.

2. Vehicle in Service Mode.

3. Verify that a test lamp illuminates between the accessory wake up serial data 2 circuit terminal 2 X1 and ground.

If the test lamp does not illuminate

1. Vehicle OFF and all vehicle systems OFF, remove the test lamp, disconnect the X2 harness connector at the K114B Hybrid/EV Powertrain Control Module 2.

2. Test for less than 2 Ω between the G1 A/C Compressor wake up circuit terminal 2 X1 and the K114B Hybrid/EV Powertrain Control Module 2 wake up circuit terminal 43 X2.

If 2 Ω or greater, repair the open/high resistance in the accessory wake up serial data 2 circuit.

If less than 2 Ω

3. Vehicle in Service Mode.

4. Verify that a test lamp illuminates between the K114B Hybrid/EV Powertrain Control Module 2 accessory wake up serial data circuit terminal 67 X2 and ground.

If the test lamp does not illuminate, test the accessory wake up serial data circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 Body Control Module.

If the test lamp illuminates

5. Replace the K114B Hybrid/EV Powertrain Control Module 2.

If the test lamp illuminates

4. Test or replace the G1 A/C Compressor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for device replacement, programming and setup

DTC P16B8-P16BA: ELECTRIC A/C COMPRESSOR CONTROL MODULE

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.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P16B8

Electric A/C Compressor Control Module Random Access Memory Performance

DTC P16B9

Electric A/C Compressor Control Module Read Only Memory Performance

DTC P16BA

Electric A/C Compressor Control Module Long Term Memory Performance For symptom byte information, refer to Symptom Byte List .

Circuit/System Description

The A/C Compressor will diagnose its own systems and determine when a fault condition is present. This diagnostic applies to internal microprocessor integrity conditions within the A/C compressor. This fault is internal to the A/C compressor and no external circuits are involved.

Conditions for Running the DTC

System voltage is greater than 10.25 V.

The device is awake and communicating.

Conditions for Setting the DTC

The device has detected an internal malfunction.

Action Taken When the DTC Sets

DTCs P16B8, P16B9, and P16BA are type A DTCs.

Conditions for Clearing the DTC

DTCs P16B8, P16B9, and P16BA are type A DTCs.

After the vehicle has been OFF for a sufficient amount of time to allow the devices to enter a sleep mode, the devices will re-enable the output on the following ignition cycle and the DTC will become history.

Circuit/System Verification

1. Vehicle in Service Mode.

2. Verify that DTC P16B8, P16B9, or P16BA is not set.

If any of the DTCs are set

Replace the G1 A/C Compressor.

If none of the DTCs are set

3. All OK

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for device replacement, programming and setup

DTC P1E8E-P1E91, P1E94-P1E97, P1E9A-P1E9D, P1EA0-P1EA3, P1F06-P1F09, P1FAC-P1FC2, P1FCF-P1FD4, P1FF3, P3031-P3034, P3037, P303C-P303F, OR P3042: HYBRID/EV BATTERY INTERFACE CONTROL MODULE

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.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P1E8E

Hybrid/EV Battery Interface Control Module 1 Performance

DTC P1E8F

Hybrid/EV Battery Interface Control Module 1 Random Access Memory Performance

DTC P1E90

Hybrid/EV Battery Interface Control Module 1 Read Only Memory Performance

DTC P1E91

Hybrid/EV Battery Interface Control Module 1 Long Term Memory Performance

DTC P1E94

Hybrid/EV Battery Interface Control Module 2 Performance

DTC P1E95

Hybrid/EV Battery Interface Control Module 2 Random Access Memory Performance

DTC P1E96

Hybrid/EV Battery Interface Control Module 2 Read Only Memory Performance

DTC P1E97

Hybrid/EV Battery Interface Control Module 2 Long Term Memory Performance

DTC P1E9A

Hybrid/EV Battery Interface Control Module 3 Performance

DTC P1E9B

Hybrid/EV Battery Interface Control Module 3 Random Access Memory Performance

DTC P1E9C

Hybrid/EV Battery Interface Control Module 3 Read Only Memory Performance

DTC P1E9D

Hybrid/EV Battery Interface Control Module 3 Long Term Memory Performance

DTC P1EA0

Hybrid/EV Battery Interface Control Module 4 Performance

DTC P1EA1

Hybrid/EV Battery Interface Control Module 4 Random Access Memory Performance

DTC P1EA2

Hybrid/EV Battery Interface Control Module 4 Read Only Memory Performance

DTC P1EA3

Hybrid/EV Battery Interface Control Module 4 Long Term Memory Performance

DTC P1F06

Hybrid/EV Battery Interface Control Module 1 Processor Performance

DTC P1F07

Hybrid/EV Battery Interface Control Module 2 Processor Performance

DTC P1F08

Hybrid/EV Battery Interface Control Module 3 Processor Performance

DTC P1F09

Hybrid/EV Battery Interface Control Module 4 Processor Performance

DTC P1FAC

Hybrid/EV Battery Interface Control Module 5 Read Only Memory Performance

DTC P1FAD

Hybrid/EV Battery Interface Control Module 7 Read Only Memory Performance

DTC P1FAE

Hybrid/EV Battery Interface Control Module 8 Read Only Memory Performance

DTC P1FAF

Hybrid/EV Battery Interface Control Module 9 Read Only Memory Performance

DTC P1FB0

Hybrid/EV Battery Interface Control Module 10 Read Only Memory Performance

DTC P1FB1

Hybrid/EV Battery Interface Control Module 5 Random Access Memory Performance

DTC P1FB2

Hybrid/EV Battery Interface Control Module 6 Random Access Memory Performance

DTC P1FB3

Hybrid/EV Battery Interface Control Module 7 Random Access Memory Performance

DTC P1FB4

Hybrid/EV Battery Interface Control Module 8 Random Access Memory Performance

DTC P1FB5

Hybrid/EV Battery Interface Control Module 9 Random Access Memory Performance

DTC P1FB6

Hybrid/EV Battery Interface Control Module 10 Random Access Memory Performance

DTC P1FB7

Hybrid/EV Battery Interface Control Module 5 Long Term Memory Performance

DTC P1FB8

Hybrid/EV Battery Interface Control Module 6 Long Term Memory Performance

DTC P1FB9

Hybrid/EV Battery Interface Control Module 7 Long Term Memory Performance

DTC P1FBA

Hybrid/EV Battery Interface Control Module 8 Long Term Memory Performance

DTC P1FBB

Hybrid/EV Battery Interface Control Module 9 Long Term Memory Performance

DTC P1FBC

Hybrid/EV Battery Interface Control Module 10 Long Term Memory Performance

DTC P1FBD

Hybrid/EV Battery Interface Control Module 5 Performance

DTC P1FBE

Hybrid/EV Battery Interface Control Module 6 Performance

DTC P1FBF

Hybrid/EV Battery Interface Control Module 7 Performance

DTC P1FC0

Hybrid/EV Battery Interface Control Module 8 Performance

DTC P1FC1

Hybrid/EV Battery Interface Control Module 9 Performance

DTC P1FC2

Hybrid/EV Battery Interface Control Module 10 Performance

DTC P1FCF

Hybrid/EV Battery Interface Control Module 5 Processor Performance

DTC P1FD0

Hybrid/EV Battery Interface Control Module 6 Processor Performance

DTC P1FD1

Hybrid/EV Battery Interface Control Module 7 Processor Performance

DTC P1FD2

Hybrid/EV Battery Interface Control Module 8 Processor Performance

DTC P1FD3

Hybrid/EV Battery Interface Control Module 9 Processor Performance

DTC P1FD4

Hybrid/EV Battery Interface Control Module 10 Processor Performance

DTC P1FF3

Hybrid/EV Battery Interface Control Module 6 Read Only Memory Performance

DTC P3031

Hybrid/EV Battery Interface Control Module 11 Read Only Memory

DTC P3032

Hybrid/EV Battery Interface Control Module 11 Random Access Memory

DTC P3033

Hybrid/EV Battery Interface Control Module 11 Long Term Memory Performance

DTC P3034

Hybrid/EV Battery Interface Control Module 11 Performance

DTC P3037

Hybrid/EV Battery Interface Control Module 11 Processor Performance

DTC P303C

Hybrid/EV Battery Interface Control Module 12 Read Only Memory

DTC P303D

Hybrid/EV Battery Interface Control Module 12 Random Access Memory

DTC P303E

Hybrid/EV Battery Interface Control Module 12 Long Term Memory Performance

DTC P303F

Hybrid/EV Battery Interface Control Module 12 Performance

DTC P3042

Hybrid/EV Battery Interface Control Module 12 Processor Performance For symptom byte information, refer to Symptom Byte List .

Circuit/System Description

The Hybrid/EV Battery Interface Control Modules will diagnose their own systems and determine when a fault condition is present. This diagnostic applies to internal microprocessor integrity conditions within the Hybrid/EV Battery Interface Control Modules. This fault is internal to the Hybrid/EV Battery Interface Control

Modules and no external circuits are involved.

Conditions for Running the DTC

The device is awake.

The system voltage is at least 9 V.

DTC U2603 - U2606 or U2617 - U2624 is not set.

Conditions for Setting the DTC

The device has detected an internal malfunction.

Action Taken When the DTC Sets

DTCs P1E8E - P1E91, P1E94 - P1E97, P1E9A - P1E9D, P1EA0 - P1EA3, P1F06 - P1F09, P1FAC - P1FC2, P1FCF - P1FD4, P1FF3, P3031 - P3034, P3037, P303C - P303F, and P3042 are type A DTCs.

Conditions for Clearing the DTC

DTCs P1E8E - P1E91, P1E94 - P1E97, P1E9A - P1E9D, P1EA0 - P1EA3, P1F06 - P1F09, P1FAC - P1FC2, P1FCF - P1FD4, P1FF3, P3031 - P3034, P3037, P303C - P303F, and P3042 are type A DTCs.

Diagnostic Aids

The Hybrid/EV Battery Interface Control Modules 1 - 12 are all internal to the Battery Energy Control Module.

If stored only as a history DTC and not retrieved as a current DTC, do not replace the device.

Reference Information

Schematic Reference

Data Communication Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Data Link Communications Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool References

Control Module References for scan tool information

Circuit/System Verification

WARNING: Always perform the High Voltage Disabling procedure prior to servicing any High Voltage component or connection. Personal Protection Equipment (PPE) and proper procedures must be followed.

The High Voltage Disabling procedure includes the following steps: Identify how to disable high voltage.

Identify how to test for the presence of high voltage.

Identify condition under which high voltage is always present and personal protection equipment (PPE) and proper procedures must be followed.

Before working on any high voltage system, be sure to wear the following Personal Protection Equipment:

Safety glasses with appropriate side shields when within 15 meters (50 feet) of the vehicle, either indoors or outdoors.

Certified and up-to-date Class "0" Insulation gloves rated at 1000V with leather protectors.

Visually and functionally inspect the gloves before use.

Wear the Insulation gloves with leather protectors at all times when working with the high voltage battery assembly, whether the system is energized or not.

Failure to follow the procedures may result in serious injury or death.

1. Vehicle in Service Mode.

2. Verify that DTC P1E8E - P1E91, P1E94 - P1E97, P1E9A - P1E9D, P1EA0 - P1EA3, P1F06 - P1F09, P1FAC - P1FC2, P1FCF - P1FD4, P1FF3, P3031 - P3034, P3037, P303C - P303F, or P3042 is not set.

If any of the DTCs are set

Replace the K16 Battery Energy Control Module.

If none of the DTCs are set

3. All OK

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for device replacement, programming and setup

DTC P1EB1: HYBRID/EV BATTERY INTERFACE CONTROL MODULE SOFTWARE INCOMPATIBLE

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.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P1EB1

Hybrid/EV Battery Interface Control Module Software Incompatible For symptom byte information, refer to Symptom Byte List .

Circuit/System Description

This is the software incompatibility issue between the Hybrid/EV Battery Interface Control Modules and the Battery Energy Control Module. No external circuits are involved.

Conditions for Running the DTC

Vehicle ON.

The system voltage is at least 9 V.

DTC U2401, U2603, U2604, U2605, or U2606 is not set.

Conditions for Setting the DTC

Any one of the Hybrid/EV Battery Interface Control Module software revision does not match.

Battery Energy Control Module software and Hybrid/EV Battery Interface Control Module software are incompatible.

Action Taken When the DTC Sets

Slave data that are incompatible with the Battery Energy Control Module software is set to Invalid, 0 V and -40°C (-40°F).

DTC P1EB1 is a type A DTC.

Conditions for Clearing the DTC DTC P1EB1 is a type A DTC. Diagnostic Aids

If stored only as a history DTC and not retrieved as a current DTC, do not replace the device.

Circuit/System Verification

WARNING: Always perform the High Voltage Disabling procedure prior to servicing any

High Voltage component or connection. Personal Protection Equipment (PPE) and proper procedures must be followed.

The High Voltage Disabling procedure includes the following steps: Identify how to disable high voltage.

Identify how to test for the presence of high voltage.

Identify condition under which high voltage is always present and personal protection equipment (PPE) and proper procedures must be followed.

Before working on any high voltage system, be sure to wear the following Personal Protection Equipment:

Safety glasses with appropriate side shields when within 15 meters (50 feet) of the vehicle, either indoors or outdoors.

Certified and up-to-date Class "0" Insulation gloves rated at 1000V with leather protectors.

Visually and functionally inspect the gloves before use.

Wear the Insulation gloves with leather protectors at all times when working with the high voltage battery assembly, whether the system is energized or not.

Failure to follow the procedures may result in serious injury or death.

1. Vehicle in Service Mode.

2. Verify DTC P1EB1 is not set.

If DTC P1EB1 is set

1. Program the K16 Battery Energy Control Module.

2. Verify the DTC does not set.

If the DTC sets without other DTCs set, replace the K16 Battery Energy Control Module.

If the DTC sets along with any of the DTCs P1EB2, P1EB3, P1EB4, or P1EB5 set, refer to

DTC P1EB2-P1EB5, P1FA6-P1FAB, P3030, or P303B.

If the DTC does not set

3. All OK.

If DTC P1EB1 is not set

3. All OK

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for device replacement, programming and setup

DTC P1EB2-P1EB5, P1FA6-P1FAB, P3030, OR P303B: HYBRID/EV BATTERY INTERFACE CONTROL MODULE

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.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P1EB2

Hybrid/EV Battery Interface Control Module 1 Not Programmed

DTC P1EB3

Hybrid/EV Battery Interface Control Module 2 Not Programmed

DTC P1EB4

Hybrid/EV Battery Interface Control Module 3 Not Programmed

DTC P1EB5

Hybrid/EV Battery Interface Control Module 4 Not Programmed

DTC P1FA6

Hybrid/EV Battery Interface Control Module 5 Not Programmed

DTC P1FA7

Hybrid/EV Battery Interface Control Module 6 Not Programmed

DTC P1FA8

Hybrid/EV Battery Interface Control Module 7 Not Programmed

DTC P1FA9

Hybrid/EV Battery Interface Control Module 8 Not Programmed

DTC P1FAA

Hybrid/EV Battery Interface Control Module 9 Not Programmed

DTC P1FAB

Hybrid/EV Battery Interface Control Module 10 Not Programmed

DTC P3030

Hybrid/EV Battery Interface Control Module 11 Not Programmed

DTC P303B

Hybrid/EV Battery Interface Control Module 12 Not Programmed For symptom byte information, refer to Symptom Byte List .

Circuit/System Description

When the Battery Energy Control Module is flash programmed, the Hybrid/EV Battery Interface Control Module operating software and calibrations are provided to the Battery Energy Control Module. The Hybrid/EV Battery Interface Control Module software and calibrations are then loaded to each of the Hybrid/EV Battery Interface Control Modules from the Battery Energy Control Module. This operation is automatic and requires no operator action. At this point, if any of the Hybrid/EV Battery Interface Control Modules are not programmed correctly, the appropriate DTC is set. This fault is internal to the Hybrid/EV Battery Interface Control Modules and no external circuits are involved.

Conditions for Running the DTC

The Battery Energy Control Module is awake and communicating. The system voltage is at least 9 V.

Conditions for Setting the DTC

The Hybrid/EV Battery Interface Control Module is not programmed correctly.

Action Taken When the DTC Sets

DTCs P1EB2, P1EB3, P1EB4, P1EB5, P1FA6, P1FA7, P1FA8, P1FA9, P1FAA, P1FAB, P3030, and P303B are

type A DTCs.

Conditions for Clearing the DTC

The Hybrid/EV Battery Interface Control Module is programmed correctly.

DTCs P1EB2, P1EB3, P1EB4, P1EB5, P1FA6, P1FA7, P1FA8, P1FA9, P1FAA, P1FAB, P3030, and

P303B are type A DTCs.

Diagnostic Aids

The Hybrid/EV Battery Interface Control Modules 1 - 12 are all internal to the Battery Energy Control Module.

Reference Information

Schematic Reference

Data Communication Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Data Link Communications Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections Wiring Repairs

DTC Type Reference

Powertrain Diagnostic Trouble Code (DTC) Type Definitions

Scan Tool References

Control Module References for scan tool information

Circuit/System Verification

WARNING: Always perform the High Voltage Disabling procedure prior to servicing any High Voltage component or connection. Personal Protection Equipment (PPE) and proper procedures must be followed.

The High Voltage Disabling procedure includes the following steps: Identify how to disable high voltage.

Identify how to test for the presence of high voltage.

Identify condition under which high voltage is always present and personal protection equipment (PPE) and proper procedures must be followed.

Before working on any high voltage system, be sure to wear the following Personal Protection Equipment:

Safety glasses with appropriate side shields when within 15 meters (50 feet) of the vehicle, either indoors or outdoors.

Certified and up-to-date Class "0" Insulation gloves rated at 1000V with leather protectors.

Visually and functionally inspect the gloves before use.

Wear the Insulation gloves with leather protectors at all times when working with the high voltage battery assembly, whether the system is energized or not.

Failure to follow the procedures may result in serious injury or death.

1. Vehicle in Service Mode.

2. Verify DTC P1EB2, P1EB3, P1EB4, P1EB5, P1FA6, P1FA7, P1FA8, P1FA9, P1FAA, P1FAB, P3030, or

P303B is not set.

If any of the DTCs are set

1. Program the K16 Battery Energy Control Module.

2. Verify the DTC does not set.

If the DTC sets, replace the K16 Battery Energy Control Module. If the DTC does not set

3. All OK.

If none of the DTCs are set

3. All OK

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for device replacement, programming and setup

DTC P1EB9: HIGH VOLTAGE ENERGY MANAGEMENT COMMUNICATION BUS ENABLE 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.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC P1EB9

High Voltage Energy Management Communication Bus Enable Circuit For symptom byte information, refer to Symptom Byte List .

Diagnostic Fault Information

Circuit/System Description

The Hybrid/EV Powertrain Control Module 2 activates the high voltage energy management communication enable circuit when the vehicle is on. This circuit wakes up the devices for high voltage energy bus communication.

Conditions for Running the DTC

The system voltage is between 9 - 16 V.

The vehicle power mode master requires serial data communication to occur.

Conditions for Setting the DTC

The Hybrid/EV Powertrain Control Module 2 detects a fault in the high voltage energy management communication enable circuit.

Action Taken When the DTC Sets DTC P1EB9 is a type A DTC. Conditions for Clearing the DTC DTC P1EB9 is a type A DTC. Diagnostic Aids

Short to ground will also set multiple no communication codes for devices on high voltage energy serial data bus.

Reference Information

Schematic Reference

Data Communication Schematics Control Module References

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Data Link Communications 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-48900 HEV Safety Kit

For equivalent regional tools, refer to Special Tools .

Circuit/System Testing

WARNING: Always perform the High Voltage Disabling procedure prior to servicing any High Voltage component or connection. Personal Protection Equipment (PPE) and proper procedures must be followed.

The High Voltage Disabling procedure includes the following steps: Identify how to disable high voltage.

Identify how to test for the presence of high voltage.

Identify condition under which high voltage is always present and personal protection equipment (PPE) and proper procedures must be followed.

Before working on any high voltage system, be sure to wear the following Personal Protection Equipment:

Safety glasses with appropriate side shields when within 15 meters (50 feet) of the vehicle, either indoors or outdoors.

Certified and up-to-date Class "0" Insulation gloves rated at 1000V with leather protectors.

Visually and functionally inspect the gloves before use.

Wear the Insulation gloves with leather protectors at all times when working with the high voltage battery assembly, whether the system is energized or not.

Failure to follow the procedures may result in serious injury or death.

NOTE: Use the schematics to determine which devices are on the K114B Hybrid/EV Powertrain Control Module 2 terminal 65 X2 high voltage energy management communication enable circuit. Use the connector end views to identify the B+, ignition, and high voltage energy management communication enable circuit terminals for each of those devices.

1. Vehicle OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. Disconnect the X2 harness connector at the K114B Hybrid/EV Powertrain Control Module 2. It may take up to 2 min for all vehicle systems to power down.

2. Test for greater than 100 Ω, but less than infinite resistance, between the high voltage energy management communication enable circuit terminal 65 X2 and ground.

If 100 Ω or less

Refer to Testing the High Voltage Energy Management Communication Enable Circuits for a Short to Ground.

If infinite resistance

Test for an open/high resistance in the high voltage energy management communication enable

circuit.

If greater than 100 Ω and less than infinite resistance

3. Vehicle in Service Mode.

4. Verify that a test lamp illuminates between each B+ circuit terminal 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, verify the fuse is not open and there is voltage at the fuse.

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 K114B Hybrid/EV Powertrain Control Module 2.

If the test lamp illuminates

5. Verify that a test lamp illuminates between each ignition circuit terminal 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 ignition circuit end to end.

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

If less than 2 Ω, verify the fuse is OK and there is voltage at the fuse.

If the test lamp does not illuminate and the circuit fuse is open

1. Vehicle OFF.

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

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

If infinite resistance, replace the K114B Hybrid/EV Powertrain Control Module 2.

If the test lamp illuminates

6. Replace the K114B Hybrid/EV Powertrain Control Module 2.

Testing the High Voltage Energy Management Communication Enable Circuits for a Short to Ground

1. Perform the High Voltage Disabling procedure. Refer to High Voltage Disabling .

2. Reconnect the 12 V battery.

3. Vehicle OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. Disconnect the harness connector at an easily accessible device that shares the K114B Hybrid/EV Powertrain Control Module 2 terminal 65 X2 high voltage energy management communication enable circuit. It may take up to 2 min for all vehicle systems to power down.

4. Test for less than 100 Ω between the K114B Hybrid/EV Powertrain Control Module 2 high voltage energy management communication enable circuit terminal 65 X2 and ground.

If 100 Ω or greater

Replace the device that was just disconnected.

If less than 100 Ω

5. Repeat step 3 until all devices on the K114B Hybrid/EV Powertrain Control Module 2 high voltage energy management communication enable circuit terminal 65 X2 have been disconnected.

6. Repair the short to ground on the high voltage energy management communication enable circuit.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Control Module References for device replacement, programming and setup.

DTC P1EB9: HIGH VOLTAGE ENERGY MANAGEMENT COMMUNICATION BUS ENABLE 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.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC P1EC1

Battery Energy Control Module High Voltage Energy Management Communication Bus Enable Circuit Low Voltage

For symptom byte information, refer to Symptom Byte List .

Diagnostic Fault Information

Circuit/System Description

The Hybrid/EV Powertrain Control Module 2 activates the high voltage energy management communication enable circuit when the vehicle is on. The high voltage energy management communication enable circuit wakes up the Battery Energy Control Module for serial data communication.

The Battery Energy Control Module compares the high voltage energy management communication enable hardwire signal with a Hybrid/EV Powertrain Control Module 2 serial data message indicating that the high voltage energy management communication enable signal is active. If the high voltage energy management communication enable hardwire signal is low when the serial data message indicates it should be high, then DTC P1EC1 is set.

Conditions for Running the DTC

The device is awake and communicating. The system voltage is at least 9 V.

DTCs U2602, U180B, P1A0C, or P1A07 is not set.

Conditions for Setting the DTC

P1EC1

The ignition voltage on the high voltage energy management communication enable circuit is less than 5 V.

Action Taken When the DTC Sets

DTCs P1EC1 and P1EC2 are type A DTCs.

Conditions for Clearing the DTC

P1EC1

The ignition voltage on the high voltage energy management communication enable circuit is at least 5 V for 10 s.

DTCs P1EC1 and P1EC2 are type A DTCs.

Diagnostic Aids

Short to ground will also set multiple no communication codes for devices on high voltage management serial data bus.

Reference Information

Schematic Reference

Data Communication Schematics Control Module References

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

INLINE HARNESS CONNECTOR END VIEWS - INDEX

Description and Operation

Data Link Communications 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-48900 HEV Safety Kit

EL-50211 Low Voltage Jumper Harness Extension

For equivalent regional tools, refer to Special Tools .

Circuit/System Verification

1. Vehicle in Service Mode.

2. Verify that DTC P1EB9 or U185B is not set.

If any of the DTCs are set

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

If none of the DTCs are set

3. Refer to Circuit/System Testing.

Circuit/System Testing

WARNING: Always perform the High Voltage Disabling procedure prior to servicing any High Voltage component or connection. Personal Protection Equipment (PPE) and proper procedures must be followed.

The High Voltage Disabling procedure includes the following steps: Identify how to disable high voltage.

Identify how to test for the presence of high voltage.

Identify condition under which high voltage is always present and personal protection equipment (PPE) and proper procedures must be followed.

Before working on any high voltage system, be sure to wear the following Personal Protection Equipment:

Safety glasses with appropriate side shields when within 15 meters (50 feet) of the vehicle, either indoors or outdoors.

Certified and up-to-date Class "0" Insulation gloves rated at 1000V with leather protectors.

Visually and functionally inspect the gloves before use.

Wear the Insulation gloves with leather protectors at all times when working with the high voltage battery assembly, whether the system is energized or not.

Failure to follow the procedures may result in serious injury or death.

NOTE: Use the schematics and connector end views to identify the devices' high voltage energy management communication enable circuit terminals.

1. Vehicle OFF, disconnect the X357 harness connector at the A4 Hybrid/EV Battery Pack.

2. Vehicle in Service Mode.

3. Verify that a test lamp illuminates between the high voltage energy management communication enable circuit terminal 5 X357 and ground.

If the test lamp does not illuminate

1. Vehicle OFF, disconnect the X2 harness connector at the K114B Hybrid/EV Powertrain Control Module 2.

2. Test for infinite resistance between the high voltage energy management communication enable circuit terminal 5 X357 at the A4 Hybrid/EV Battery Pack 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 high voltage energy management communication enable circuit end to end between the A4 Hybrid/EV Battery Pack terminal 5 X357 and the K114B Hybrid/EV Powertrain Control Module 2 terminal 65 X2.

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

If less than 2 Ω, replace the K114B Hybrid/EV Powertrain Control Module 2.

If the test lamp illuminates

4. Vehicle OFF, connect the X357 harness connector at the A4 Hybrid/EV Battery Pack.

5. Perform the High Voltage Disabling procedure before proceeding with this diagnostic. Refer to High Voltage Disabling .

6. Reconnect the 12 V battery.

7. Vehicle OFF, connect the EL-50211 low voltage jumper harness extension.

8. Disconnect the X8 harness connector at the K16 Battery Energy Control Module.

9. Vehicle in Service Mode.

10. Verify that a test lamp illuminates between the high voltage energy management communication enable circuit terminal 10 X8 at K16 Battery Energy Control Module and ground.

If the test lamp does not illuminate

Repair the open/high resistance in the circuit.

If the test lamp illuminates

11. Replace the K16 Battery Energy Control Module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Serial Data Circuit Wiring Repairs

Control Module References for device replacement, programming and setup

DTC U0020: LOW SPEED CAN BUS

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.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC U0020

Low Speed CAN Bus

For symptom byte information, refer to Symptom Byte List .

Circuit/System Description

Devices connected to the GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the devices. The devices have programmed information about what messages are needed to be exchanged on the serial data circuits. The messages are also supervised and some periodic messages are used by the receiver device as an availability indication of the transmitter device.

Conditions for Running the DTCs

Supply voltage to the devices is in the normal operating range.

The vehicle power mode requires serial data communication to occur. The DTC U2100 does not have a current status.

Conditions for Setting the DTC

A supervised periodic message that includes the transmitter device availability has not been received.

Action Taken When the DTCs Sets

The device uses a default value for the missing parameter.

Conditions for Clearing the DTC

A current DTC clears when the malfunction is no longer present.

A history DTC clears when the device ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

Circuit/System Verification

Diagnosis of this DTC is accomplished via the symptom or an additional DTC. Refer to Scan Tool Does Not Communicate with Low Speed GMLAN Device , or Diagnostic Trouble Code (DTC) List - Vehicle .

DTC U0028: MOST BUS

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.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC U0028

MOST Bus

For symptom byte information, refer to Symptom Byte List .

Diagnostic Fault Information

Circuit/System Description

The Media Oriented Systems Transport (MOST) bus consists of a physical ring in which multimedia devices share audio, video and infotainment system control data. Each device on the MOST bus transmits and receives data via the MOST Bus Serial Data (+/- transmit/receive) circuits. The MOST bus diagnostic master is the Radio. The MOST control circuit is connected to each device on the MOST bus. Each device provides a 12 V signal on the MOST control circuit. The Radio initiates communication on the MOST bus at Vehicle "On" by toggling the MOST control circuit low for 100 ms. Once each device recognizes the wakeup signal from the Radio on the MOST control circuit, they will respond to the Radio on the MOST bus to indicate no faults are present and normal communications will commence.

Conditions for Running the DTC

The system voltage is between 9 - 16 V. The vehicle is ON.

Conditions for Setting the DTC

A fault occurs on transmit, receive, electronic control lines, or internal device failure.

Action Taken When the DTC Sets

Some or all of the infotainment system audio and displays may be inoperative.

While a current U0028 is set, the Radio will continually send 400 ms low pulses on the MOST control circuit every 2.5 s. This is a Ring Break Diagnostic indication to the devices on the ring to report a Surrogate Master Upstream Position Node.

Conditions for Clearing the DTC

The MOST initialization is successful without errors and the MOST bus resumes normal communications.

Diagnostic Aids

The EL-51578 MOST Bus Diagnostic Tool Kit when utilized will cause false GMLAN DTC's to be set as a result, along with loss of bypassed MOST device infotainment functionality. These DTC's and missing functionality should be ignored unless the system is completely assembled and a DTC or symptom is present during the repair verification steps.

To troubleshoot the intermittent condition, manipulate or wiggle MOST wiring harness and observe the Radio's DTC U0028 status and the Radio scan tool Number of MOST Communication Breaks parameter value.

If the issue still exists after performing all verification and test steps in this diagnostic procedure, bypass each MOST device individually on the MOST bus (except the Radio) while monitoring DTC U0028 status. If DTC U0028 remains current after each MOST device has been bypassed, disconnect the Radio MOST harness connector. The entire MOST ring can now be tested with all MOST devices (except the Radio) bypassed to determine if any circuit faults exist.

The Radio's DTC U0028 will be set current with all MOST devices bypassed.

Reference Information

Schematic Reference

Data Communication Schematics Control Module References

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Data Link Communications 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-51578 MOST Bus Diagnostic Tool Kit

For equivalent regional tools, refer to Special Tools .

Circuit/System Verification

1. Vehicle in Service Mode. Radio ON.

2. If equipped, verify that the A33 Media Disc Player is operative by inserting or ejecting a disk.

If the disk can not be inserted or ejected

Test the power, ground, and serial data circuits of the A33 Media Disc Player for an open/high resistance.

If the disk can be inserted or ejected

3. Verify that the scan tool communicates with each MOST device, except the A33 Media Disc Player.

If any MOST device does not communicate with the scan tool

Refer to DTC U0100-U02FF to diagnose power, ground, and serial data circuits of that MOST device.

If all MOST devices communicate with the scan tool

4. Verify that DTC U2098 or DTC U0029 02 is not set.

If any of the DTCs are set

Refer to DTC U2098 .

If none of the DTCs are set

5. Verify that DTC U0028 is not set.

If the DTC U0028 is set

1. Using the scan tool, select the MOST Bus Diagnostic Starting Point function from A11 Radio Control Functions menu.

2. Determine the fault location from A11 Radio scan tool Control Functions, MOST Bus Diagnostic Starting Point. Reference Node Locations of MOST Bus Communication Break parameter value.

3. Refer to Circuit/System Testing.

If the DTC U0028 is not set

6. Refer to Repair Verification.

Circuit/System Testing

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

NOTE: Use the Radio scan tool, schematics and specific vehicle build RPO codes to determine optional devices and to identify the following:

The MOST bus ring configuration

Each MOST device's MOST control and serial data circuit terminals

NOTE: If the A11 Radio is the first node position in the "Node Locations of MOST Bus Communication Break" range, proceed to step 8.

1. Vehicle OFF, disconnect the harness connector containing the MOST circuits at the MOST device at the first Node position reported by Node Locations of MOST Bus Communication Break parameter value.

2. Connect the appropriate connector from the EL-51578 MOST Bus Diagnostic Tool Kit to the harness connector of the MOST device to bypass this MOST device.

3. Vehicle in Service Mode.

NOTE: MOST control (ECL) voltage will toggle from 9 - 13 V to 0 V while DTC U0028 is current.

4. Test for 9 - 13 V between the ECL connector from the EL-51578 MOST Bus Diagnostic Tool Kit and ground.

If less than 9 V

1. Vehicle OFF and all vehicle systems OFF, disconnect the harness connectors at the A11 Radio.

2. Disconnect the EL-51578 MOST Bus Diagnostic Tool Kit from the harness connector of the first Node location MOST device.

3. Test for less than 2 Ω in the MOST control circuit end to end between the MOST device that was just disconnected and the A11 Radio.

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 13 V

1. Vehicle OFF, disconnect the harness connectors at the A11 Radio.

2. Disconnect the EL-51578 MOST Bus Diagnostic Tool Kit from the harness connector of the first Node location MOST device, Vehicle in Service Mode.

3. Test for less than 1 V between the MOST control circuit and ground. If 1 V or greater, repair the short to voltage in the circuit.

If less than 1 V, replace the A11 Radio.

If between 9 - 13 V

5. Verify that DTC U0028 status remains current.

If the status of DTC U0028 changes from current to history

Replace the disconnected MOST device.

If the status of DTC U0028 remains current

6. Vehicle OFF, disconnect the EL-51578 MOST Bus Diagnostic Tool Kit from the harness connector of the first Node location MOST device.

7. Reconnect the harness connector containing the MOST circuits at the first Node location MOST device.

NOTE: If the A11 Radio is the last node position in the "Node Locations of MOST Bus Communication Break" range, disconnect the harness connector containing MOST circuits at the A11 Radio and proceed to step 13.

8. Disconnect the harness connector containing the MOST circuits at the last Node location MOST device of the fault location identified by Node Locations of MOST Bus Communication Break parameter value.

9. Connect the appropriate connector from the EL-51578 MOST Bus Diagnostic Tool Kit to the harness connector of the last Node location MOST device to bypass this MOST device.

10. Vehicle in Service Mode.

11. Verify that DTC U0028 status remains current.

If the status of DTC U0028 changes from current to history

Replace the disconnected MOST device.

If the status of DTC U0028 remains current

12. Vehicle OFF, disconnect the EL-51578 MOST Bus Diagnostic Tool Kit from the harness connector of the last Node location MOST device.

13. Disconnect the harness connector containing the MOST circuits at the first Node location MOST device. The following tests will be performed on the MOST serial data circuits between the two MOST devices that are disconnected.

14. Vehicle in Service Mode.

15. Test for less than 1 V between each MOST serial data circuit and ground.

If any serial data circuits are 1 V or greater

Repair the short to voltage in the circuit.

If each serial data circuits are less than 1 V

16. Vehicle OFF, all access doors closed, and all vehicle systems OFF.

17. Test for infinite resistance between each MOST serial data circuit and ground.

If any serial data circuits are less than infinite resistance

Repair the short to ground in the circuit.

If each serial data circuits are infinite resistance

18. Test for infinite resistance between each pair of the MOST serial data circuits.

If any pair of serial data circuits are less than infinite resistance

Repair the short between the circuits.

If each pair of serial data circuits are infinite resistance

19. Test for less than 2 Ω in each MOST serial data circuit end to end.

If any serial data circuits are 2 Ω or greater

Repair the open/high resistance in the circuit between the two MOST devices.

If each serial data circuits are less than 2 Ω

20. Replace the A11 Radio.

21. Vehicle in Service Mode. Radio ON.

22. Verify that DTC U0028 does not set.

If the DTC U0028 sets

Refer to Diagnostic Aids.

If the DTC U0028 does not set

23. All OK.

Repair Instructions

Perform the Repair Verification after completing the repair.

Serial Data Circuit Wiring Repairs

Control Module References for device replacement, programming and setup

Repair Verification

1. Vehicle OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. It may take up to 2 min for all vehicle systems to power down.

2. Install any components or connectors that have been removed or replaced during diagnosis.

3. Vehicle in Service Mode.

4. Clear the DTCs.

5. Verify the A11 Radio scan tool Surrogate MOST Master Node Upstream Position parameter value is None.

If the value is not None

Disconnect the A11 Radio power or the battery cables for 1 min to reset this value to None.

If the value is None

6. All OK.

DTC U0029: MOST BUS 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.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC U0029

MOST Bus Performance

For symptom byte information, refer to Symptom Byte List .

Circuit/System Description

The Media Oriented Systems Transport (MOST) bus master device shall set DTC U0029 when the MOST bus interruptions lasts long enough to interrupt MOST communication and functions, but not long enough to break the MOST bus ring.

Conditions for Running the DTC

The system voltage is between 9 - 16 V. The vehicle is ON.

The Radio is ON.

Conditions for Setting the DTC

A current DTC sets when MOST bus communication has been interrupted more than 10 times during the monitoring cycle period.

Action Taken When the DTC Sets

Some or all of the infotainment system may be inoperative for brief periods of time.

Conditions for Clearing the DTC

A current DTC is cleared when MOST bus communication interruptions are no longer detected and the Number of MOST Communication Breaks counter remains at 0.

Diagnostic Aids

This is an intermittent connection detection DTC. All MOST device connectors should be checked for poor connections on both MOST bus circuits.

Reference Information

Schematic Reference

Data Communication Schematics Control Module References

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Data Link Communications 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 DTC U0029 is not set with symptom byte 02.

If DTC U0029 is set with symptom byte 02

Refer to DTC U2098 .

If DTC U0029 is set with other symptom bytes except 02

3. Verify that DTC U0028 is set.

If the DTC is set

Refer to DTC U0028.

If the DTC is not set

4. Refer to Testing for Intermittent Conditions and Poor Connections to test for an intermittent condition.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Serial Data Circuit Wiring Repairs

Control Module References for device replacement, programming and setup

DTC U0073 OR U2100: CONTROL MODULE COMMUNICATION BUS A OFF/CAN BUS COMMUNICATION

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.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptors

DTC U0073

Control Module Communication Bus A Off

DTC U2100

CAN Bus Communication

For symptom byte information, refer to Symptom Byte List .

Circuit/System Description

The serial data circuits are used to communicate information between the devices. The serial data circuits also connect directly to the data link connector (DLC).

Conditions for Running the DTCs

Supply voltage to the devices is in the normal operating range. The vehicle power mode requires serial data communications.

Conditions for Setting the DTC

The device setting the DTC has attempted to establish communications on the serial data circuits more than 3 times in 5 s.

Action Taken When the DTCs Sets

The device suspends all message transmission.

The device uses default values for all parameters received on the serial data circuits.

In the transmission control module, DTC U0073 will cause the transmission to go into default gears.

In the engine control module and transmission control module, DTC U0073 will cause the malfunction indicator lamp (MIL) to illuminate.

If equipped with eAssist, DTC U0073 in the hybrid powertrain control module is a type B DTC and will cause the malfunction indicator lamp to illuminate and result in the engine operating in conventional engine mode and will maintain 14 V module operation.

The device inhibits the setting of all other communication DTCs.

Conditions for Clearing the DTC

The engine control module or transmission control module turns OFF the MIL after 4 consecutive ignition cycles that the diagnostic runs and does not fail.

If equipped with eAssist, the hybrid powertrain control module turns off the MIL after the diagnostic runs and does not fail during subsequent ignition cycles. Normal operation will resume 5 s after subsequent ignition cycle.

A current DTC clears when the malfunction is no longer present.

A history DTC clears when the device ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.

Circuit/System Verification

1. Refer to Data Link References to determine which serial data communication system is used for a

specific device.

2. This DTC may not be retrieved with a current status. Diagnosis is accomplished using the symptom. Refer to Symptoms - Data Communications .

DTC U0074: CONTROL MODULE COMMUNICATION POWERTRAIN EXPANSION CAN BUS OFF

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.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC U0074

Control Module Communication Powertrain Expansion CAN Bus Off For symptom byte information, refer to Symptom Byte List .

Diagnostic Fault Information

Circuit/System Description

The serial data is transmitted on two twisted wires that allow speeds up to 500 Kb/s. The twisted pair is terminated with two 120 Ω resistors, one is internal to the engine control module (ECM) and the other can be a separate resistor in a connector assembly or in another device. The resistors are used as the load for the powertrain high speed GMLAN bus during normal vehicle operation. The powertrain high speed GMLAN is a differential bus. The powertrain high speed GMLAN serial data bus (+) and powertrain high speed GMLAN serial data (-) are driven to opposite extremes from a rest or idle level of approximately 2.5 V. Driving the lines to their extremes, adds 1 V to the powertrain high speed GMLAN serial data bus (+) circuit and subtracts 1 V from the powertrain high speed GMLAN serial data bus (-) circuit. If serial data is lost, devices will set a no communication code against the non-communicating device. Note that a loss of serial data DTC does not represent a failure of the device that set it.

Conditions for Running the DTC

The system voltage is between 9 - 16 V.

Conditions for Setting the DTC

The device setting the DTC has attempted to establish communications on the powertrain high speed GMLAN serial data circuits more than 3 times.

Action Taken When the DTC Sets

The device suspends all message transmission.

The MIL and battery indicators will illuminate, along with several DIC messages. DTC U0074 is a type A DTC.

Conditions for Clearing the DTC

A current DTC clears when the malfunction is no longer present.

A history DTC clears when the device ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

DTC U0074 is a type A DTC.

Diagnostic Aids

Sometimes, while diagnosing a specific customer concern or after a repair, you may notice a history U code present. However, there is no associated "current" or "active" status. Loss of communication U codes such as these can set for a variety of reasons. Many times, they are transparent to the vehicle operator and technician, and/or have no associated symptoms. Eventually, they will erase themselves automatically after a number of fault-free ignition cycles. This condition would most likely be attributed to one of these scenarios:

A device on the data communication circuit was disconnected while the communication circuit is awake.

Power to one or more devices was interrupted during diagnosis.

A low battery condition was present, so some devices stop communicating when battery voltage drops below a certain threshold.

Battery power was restored to the vehicle and devices on the communication circuit did not all re- initialize at the same time.

If a loss of communication U code appears in history for no apparent reason, it is most likely associated with one of the scenarios above. These are all temporary conditions and should never be interpreted as an intermittent fault, causing you to replace a part.

Do not replace a device reporting a U code. The U code identifies which device needs to be diagnosed for a communication issue.

Communication may be available between the device and the scan tool with one or more GMLAN serial data systems inoperative. This condition is due to the device using multiple GMLAN busses.

The engine will not start when there is a total malfunction of the powertrain high speed GMLAN serial data bus.

Use Data Link References to determine which devices connect to the powertrain high speed GMLAN serial data bus.

Reference Information

Schematic Reference

Data Communication Schematics Control Module References

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Data Link Communications 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: Some devices with an internal terminating resistor have a loop in the harness that connects the internal terminating resistor to the serial data circuit. When wired this way, test these loop circuits for the appropriate failure mode short to voltage, short to ground, or open/high resistance prior to replacing the device for each of the following tests.

Each device may need to be disconnected to isolate a circuit fault. Use the schematics and connector end views to identify the following:

Powertrain high speed GMLAN devices and terminating resistors the vehicle is equipped with

Device locations on the powertrain high speed GMLAN serial data circuits Each device's ground, B+, ignition, and powertrain high speed GMLAN

serial data circuit terminals

1. Refer to Data Link References to determine which devices are on the powertrain expansion bus.

2. Vehicle OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. It may take up to 2 min for all vehicle systems to power down. Disconnect the harness connectors containing the powertrain high speed GMLAN serial data circuits at an easily accessible device that is not communicating.

3. Vehicle in Service Mode.

4. Test for less than 4.5 V between each powertrain high speed GMLAN serial data circuit at the device that was just disconnected and ground.

If 4.5 V or greater

Refer to Testing the Serial Data Circuits for a Short to Voltage.

If less than 4.5 V

5. Vehicle OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. It may take up to 2 min for all vehicle systems to power down.

6. Test for greater than 100 Ω between each powertrain high speed GMLAN serial data circuit at the device that was just disconnected and ground.

If 100 Ω or less

Refer to Testing the Serial Data Circuits for a Short to Ground.

If greater than 100 Ω

7. Test for 110 - 130 Ω between each pair of the powertrain high speed GMLAN serial data circuits at the device that was just disconnected.

If less than 110 Ω

Refer to Testing the Serial Data Circuits for a Short between the Circuits.

If greater than 130 Ω

Refer to Testing the Serial Data Circuits for an Open/High Resistance.

If between 110 - 130 Ω

8. Refer to Testing the Device Circuits.

Testing the Serial Data Circuits for a Short to Voltage

1. Vehicle OFF, disconnect the harness connectors with the powertrain high speed GMLAN serial data circuits at another device, in the direction of the circuit shorted to voltage, Vehicle in Service Mode.

2. Test for greater than 4.5 V between each serial data circuit at the device connector that was just disconnected and ground.

If each serial data circuit is 4.5 V or less

1. Vehicle OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. It may take up to 2 min for all vehicle systems to power down.

2. Test for less than 10 Ω between each of the device's ground circuit terminals and ground. If 10 Ω or greater, repair the open/high resistance in the circuit.

If less than 10 Ω, replace the device that was disconnected.

If any serial data circuit is greater than 4.5 V

3. Repeat step 1 until one of the following conditions are isolated:

A short to voltage on the serial data circuit between two devices or splice packs, if equipped. A short to voltage on the serial data circuit between a device and a terminating resistor.

Testing the Serial Data Circuits for a Short to Ground

1. Vehicle OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. It may take up to 2 min for all vehicle systems to power down.

2. Disconnect the harness connectors containing the powertrain high speed GMLAN serial data circuits at another device, in the direction of the circuit shorted to ground.

3. Test for greater than 100 Ω between each serial data circuit at the device connector that was just disconnected and ground.

If all serial data circuits are 100 Ω or greater

Replace the device that was disconnected.

If any serial data circuit is less than 100 Ω

4. Repeat step 2 until one of the following conditions are isolated:

A short to ground on the serial data circuit between two devices or splice packs, if equipped. A short to ground on the serial data circuit between a device and a terminating resistor.

Testing the Serial Data Circuits for a Short between the Circuits

1. Vehicle OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. It may take up to 2 min for all vehicle systems to power down.

2. Connect the harness connectors at the device that was previously disconnected.

3. Disconnect the harness connectors containing the powertrain high speed GMLAN serial data circuits at another device, in the direction of the circuit shorted together.

4. Test for greater than 110 Ω between each pair of serial data circuits at the device connector that was just disconnected.

If each pair of serial data circuits is 110 Ω or greater

Replace the device that was disconnected.

If any pair of serial data circuits is less than 110 Ω

5. Repeat step 2 until one of the following conditions are isolated:

Serial data circuits shorted together between two devices or splice packs, if equipped. Serial data circuits shorted together between a device and a terminating resistor.

A shorted terminating resistor.

Testing the Serial Data Circuits for an Open/High Resistance

1. Vehicle OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. It may take up to 2 min for all vehicle systems to power down.

2. Connect the harness connectors at the device that was previously disconnected.

3. Disconnect the harness connectors containing the powertrain high speed GMLAN serial data circuits at another device, in the direction of the circuit with the open/high resistance.

4. Test for less than 130 Ω between each pair of serial data circuits at the device connector that was just disconnected.

If each pair of serial data circuits is 130 Ω or less

Replace the device that was disconnected.

If any pair of serial data circuits is greater than 130 Ω

5. Repeat step 2 until one of the following conditions are isolated:

An open/high resistance on the serial data circuit between two devices or splice packs, if equipped. An open/high resistance on the serial data circuit between a device and a terminating resistor.

An open/high resistance terminating resistor.

Testing the Device Circuits

1. Vehicle OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. It may take up to 2 min for all vehicle systems to power down.

2. Test for less than 10 Ω between each ground circuit terminal at the device that was just disconnected 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. If equipped, verify a test lamp illuminates between each B+ circuit terminal and ground.

If the test lamp does not illuminate and the circuit fuse is good

1. Vehicle 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 less than 2 Ω, verify the fuse is not open and there is voltage at the fuse.

If the test lamp does not illuminate and the circuit fuse is open

1. Vehicle OFF, remove the test lamp.

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 disconnected device.

If the test lamp illuminates

4. Vehicle in Service Mode.

5. If equipped, verify a test lamp illuminates between each ignition circuit terminal, which has a fuse in the circuit, and ground.

If the test lamp does not illuminate and the circuit fuse is good

1. Vehicle OFF, remove the test lamp.

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

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

If less than 2 Ω, verify the fuse is OK and there is voltage at the fuse.

If the test lamp does not illuminate and the circuit fuse is open

1. Vehicle OFF, remove the test lamp.

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

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

If the test lamp illuminates

6. If equipped, verify a test lamp illuminates between each ignition circuit terminal, which is controlled by a control module, and ground.

If the test lamp does not illuminate

1. Vehicle OFF, remove the test lamp, disconnect the harness connectors at the control module that controls the ignition circuit.

2. Test for infinite resistance between the ignition 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 ignition circuit end to end.

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

If less than 2 Ω, replace the control module that controls the ignition circuit.

If the test lamp illuminates

7. Replace the device that was disconnected.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Serial Data Circuit Wiring Repairs

Control Module References for device replacement, programming and setup

DTC U0075: CONTROL MODULE COMMUNICATION OBJECT DETECTION CAN BUS OFF

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.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC U0075 00

Control Module Communication Object Detection CAN Bus Off

Diagnostic Fault Information

Circuit/System Description

The devices connected to the object high speed GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the devices when the ignition switch is in any position other than OFF. The object high speed GMLAN serial data bus uses terminating resistors that are in parallel with the object high speed GMLAN (+) and (-) circuits.

Conditions for Running the DTC

The system voltage is between 9 - 16 V.

Conditions for Setting the DTC

A supervised periodic message that includes the transmitter device availability has not been received.

Action Taken When the DTC Sets Specific subsystems will not function. Conditions for Clearing the DTC

A current DTC clears when the malfunction is no longer present.

A history DTC clears when the device ignition cycle counter reaches the reset threshold of 50, without a repeat of the malfunction.

Diagnostic Aids

Use the Data Link References to identify the object detection high speed GMLAN devices.

Sometimes, while diagnosing a specific customer concern or after a repair, you may notice a history U code present. However, there is no associated "current" or "active" status. Loss of communication U codes such as these can set for a variety of reasons. Many times, they are transparent to the vehicle operator and technician, and/or have no associated symptoms. Eventually, they will erase themselves automatically after a number of fault-free ignition cycles. This condition would most likely be attributed to one of these scenarios:

A device on the data communication circuit was disconnected while the communication circuit is awake.

Power to one or more devices was interrupted during diagnosis.

A low battery condition was present, so some devices stop communicating when battery voltage drops below a certain threshold.

Battery power was restored to the vehicle and devices on the communication circuit did not all re- initialize at the same time.

If a loss of communication U code appears in history for no apparent reason, it is most likely associated with one of the scenarios above. These are all temporary conditions and should never be interpreted as an intermittent fault, causing you to replace a part.

Do not replace a device reporting a U code. The U code identifies which device needs to be diagnosed for a communication issue.

Communication may be available between some devices and the scan tool with the object high speed GMLAN serial data system inoperative. This condition is due to those devices using multiple serial data communication systems.

An open in the DLC ground circuit terminal 5 will allow the scan tool to operate but not communicate with the vehicle.

Technicians may find various Local Area Network (LAN) communication Diagnostic Trouble Codes (DTC).

Some devices may not have internal protection for specific voltage outputs and may open a battery positive voltage or ignition voltage source fuse. If a voltage input fuse is open and no short is found in that circuit, ensure that no device output voltage circuit is shorted to ground before replacing the device.

Reference Information

Schematic Reference

Data Communication Schematics Control Module References

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Data Link Communications 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. Ignition ON/Vehicle In Service Mode.

2. Verify two or more devices are not communicating on the object high speed GMLAN serial data circuit. Refer to Data Link References to determine how many devices should be communicating on this bus.

If only one device is not communicating

Refer to Circuit/System Testing - Testing the Device Circuits.

If two or more devices are not communicating

3. Ignition/Vehicle OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. It may take up to 2 min for all vehicle systems to power down. Disconnect the scan tool from the X84 Data Link Connector. The following tests will be done at the X84 Data Link Connector.

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

If 10 Ω or greater

1. Ignition/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

5. Ignition ON/Vehicle In Service Mode.

6. Test for less than 4.5 V between the serial data circuits listed below and ground: Terminal 3

Terminal 11

If 4.5 V or greater

Refer to Circuit/System Testing - Testing the Serial Data Circuits for a Short to Voltage.

If less than 4.5 V

7. Ignition/Vehicle OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. It may take up to 2 min for all vehicle systems to power down.

8. Test for greater than 100 Ω between the serial data circuits listed below and ground: Terminal 3

Terminal 11

If 100 Ω or less

Refer to Circuit/System Testing - Testing the Serial Data Circuits for a Short to Ground.

If greater than 100 Ω

9. Test for 50 - 70 Ω between the serial data circuit terminals 3 and 11.

If less than 35 Ω

Refer to Circuit/System Testing - Testing the Serial Data Circuits for a Short between the Circuits.

If between 35 - 50 Ω

There may be a third terminating resistor between the serial data circuits. This can happen if the incorrect device is installed. Some devices are available with and without the terminating resistors installed to reduce the need of terminating resistors in the wiring harness. Refer to Circuit/System Testing - Testing the Serial Data Circuits for a Short between the Circuits.

If greater than 70 Ω but less than infinite

Refer to Circuit/System Testing - Testing the Serial Data Circuits for an Open/High Resistance.

If infinite resistance

Repair the open/high resistance in the circuit between the X84 Data Link Connector and the first splice/device in the serial data circuit.

If between 50 - 70 Ω

10. Refer to Circuit/System Testing - Testing the Device Circuits.

Circuit/System Testing

NOTE: Some devices with an internal terminating resistor have a loop in the harness that connects the internal terminating resistor to the serial data circuit. When wired this way, test these loop circuits for the appropriate failure mode short to voltage, short to ground, or open/high resistance prior to replacing the device for each of the following tests. Each device may need to be disconnected to isolate a circuit fault. Use the schematics and connector end views to identify the following:

Object high speed GMLAN devices and terminating resistors the vehicle is equipped with

Device locations on the object high speed GMLAN serial data circuits

Each device's ground, B+, ignition, and object high speed GMLAN serial data circuit terminals

NOTE: Circuit/System Verification must be performed before proceeding with Circuit/System Testing.

Testing the Serial Data Circuits for a Short to Voltage

1. Ignition/Vehicle OFF, disconnect the harness connectors with the object high speed GMLAN serial data circuits at an easily accessible device, ignition ON/Vehicle In Service Mode.

2. Test for greater than 4.5 V between each serial data circuit at the device connector that was just disconnected and ground.

If each serial data circuit is 4.5 V or less

1. Ignition/Vehicle OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. It may take up to 2 min for all vehicle systems to power down.

2. Test for less than 10 Ω between each of the device's ground circuit terminals and ground. If 10 Ω or greater, repair the open/high resistance in the circuit.

If less than 10 Ω, replace the device that was disconnected.

If any serial data circuit is greater than 4.5 V

3. Ignition/Vehicle OFF, disconnect the harness connectors with the object high speed GMLAN serial data circuits at another device, in the direction of the circuit shorted to voltage, ignition ON/Vehicle In Service Mode.

4. Test for greater than 4.5 V between each serial data circuit at the device connector that was just disconnected and ground.

If each serial data circuit is 4.5 V or less

1. Ignition/Vehicle OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. It may take up to 2 min for all vehicle systems to power down.

2. Test for less than 10 Ω between each of the device's ground circuit terminals and ground. If 10 Ω or greater, repair the open/high resistance in the circuit.

If less than 10 Ω, replace the device that was disconnected.

If any serial data circuit is greater than 4.5 V

5. Repeat step 3 until one of the following conditions are isolated:

A short to voltage on the serial data circuit between two devices or splice packs, if equipped. A short to voltage on the serial data circuit between a device and a terminating resistor.

Testing the Serial Data Circuits for a Short to Ground

1. Ignition/Vehicle OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. It may take up to 2 min for all vehicle systems to power down. Disconnect the harness connectors with the object high speed GMLAN serial data circuits at an easily accessible device.

2. Test for greater than 100 Ω between each object high speed GMLAN serial data circuit at the device connector that was just disconnected and ground.

If each serial data circuit is 100 Ω or greater

Replace the device that was disconnected.

If any serial data circuit is less than 100 Ω

3. Disconnect the harness connectors with the object high speed GMLAN serial data circuits at another device, in the direction of the circuit shorted to ground.

4. Test for greater than 100 Ω between each object high speed GMLAN serial data circuit at the device connector that was just disconnected and ground.

If both serial data circuits are 100 Ω or greater

Replace the device that was disconnected.

If any serial data circuit is less than 100 Ω

5. Repeat step 3 until one of the following conditions are isolated:

A short to ground on the serial data circuit between two devices or splice packs, if equipped.

A short to ground on the serial data circuit between a device and a terminating resistor.

A short to ground on the serial data circuit between the X84 Data Link Connector and the first device or splice pack.

Testing the Serial Data Circuits for a Short between the Circuits

1. Ignition/Vehicle OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. It may take up to 2 min for all vehicle systems to power down. Disconnect the harness connectors with the object high speed GMLAN serial data circuits at an easily accessible device that is not communicating.

2. Test for greater than 110 Ω between each pair of object high speed GMLAN serial data circuits at the device connector that was just disconnected.

If each pair of serial data circuits is 110 Ω or greater

Replace the device that was disconnected.

If any pair of serial data circuits is less than 110 Ω

3. Connect the harness connectors at the device that was disconnected.

4. Disconnect the harness connectors with the object high speed GMLAN serial data circuits at another device, in the direction of the circuit shorted together.

5. Test for greater than 110 Ω between each pair of object high speed GMLAN serial data circuits at the device connector that was just disconnected.

If each pair of serial data circuits is 110 Ω or greater

Replace the device that was disconnected.

If any pair of serial data circuits is less than 110 Ω

6. Repeat step 3 until one of the following conditions are isolated:

Serial data circuits shorted together between two devices or splice packs, if equipped. Serial data circuits shorted together between a device and a terminating resistor.

Serial data circuits shorted together between the X84 Data Link Connector and the first device or splice pack.

A shorted terminating resistor.

Testing the Serial Data Circuits for an Open/High Resistance

1. Ignition/Vehicle OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. It may take up to 2 min for all vehicle systems to power down. Disconnect the harness connectors with the object high speed GMLAN serial data circuits at an easily accessible device that is not communicating.

2. Test for less than 130 Ω between each pair of object high speed GMLAN serial data circuits at the device connector that was just disconnected.

If each pair of serial data circuits is 130 Ω or less

Replace the device that was disconnected.

If any pair of serial data circuits is greater than 130 Ω

3. Connect the harness connectors at the device that was disconnected.

4. Disconnect the harness connectors with the object high speed GMLAN serial data circuits at another device, in the direction of the circuit with the open/high resistance.

5. Test for less than 130 Ω between each pair of object high speed GMLAN serial data circuits at the device connector that was just disconnected.

If each pair of serial data circuits is 130 Ω or less

Replace the device that was disconnected.

If any pair of serial data circuits is greater than 130 Ω

6. Repeat step 3 until one of the following conditions are isolated:

An open/high resistance on the serial data circuit between two devices or splice packs, if equipped. An open/high resistance on the serial data circuit between a device and a terminating resistor.

An open/high resistance terminating resistor.

Testing the Device Circuits

1. Ignition/Vehicle OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. It may take up to 2 min for all vehicle systems to power down. Disconnect the harness connectors at an easily accessible device that is not communicating.

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

If 10 Ω or greater

1. Ignition/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. Ignition ON/Vehicle In Service Mode.

4. If equipped, verify a test lamp illuminates between each B+ circuit terminal and ground.

If the test lamp does not illuminate and the circuit fuse is good

1. Ignition/Vehicle 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 less than 2 Ω, verify the fuse is not open and there is voltage at the fuse.

If the test lamp does not illuminate and the circuit fuse is open

1. Ignition/Vehicle OFF, remove the test lamp.

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 disconnected device.

If the test lamp illuminates

5. If equipped, verify a test lamp illuminates between each ignition circuit terminal, which has a fuse in the circuit, and ground.

If the test lamp does not illuminate and the circuit fuse is good

1. Ignition/Vehicle OFF, remove the test lamp.

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

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

If less than 2 Ω, verify the fuse is OK and there is voltage at the fuse.

If the test lamp does not illuminate and the circuit fuse is open

1. Ignition/Vehicle OFF, remove the test lamp.

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

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

If the test lamp illuminates

6. If equipped, verify a test lamp illuminates between each ignition circuit terminal, which is controlled by a control module, and ground.

If the test lamp does not illuminate

1. Ignition/Vehicle OFF, remove the test lamp, disconnect the harness connectors at the control module that controls the ignition circuit.

2. Test for infinite resistance between the ignition 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 ignition circuit end to end.

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

If less than 2 Ω, replace the control module that controls the ignition circuit.

If the test lamp illuminates

7. Ignition/Vehicle OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. It may take up to 2 min for all vehicle systems to power down.

8. Test for less than 2 Ω in each object high speed GMLAN serial data circuit end to end between the device harness connector and the appropriate X84 Data Link Connector terminals listed below.

X84 Data Link Connector terminal 3 X84 Data Link Connector terminal 11 If 2 Ω or greater

Repair the open/high resistance in the serial data circuit.

If less than 2 Ω

9. Replace the device that was disconnected.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Serial Data Circuit Wiring Repairs

Control Module References for device replacement, programming and setup

DTC U0077: CONTROL MODULE COMMUNICATION CHASSIS EXPANSION CAN BUS OFF

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.

Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor

DTC U0077

Control Module Communication Chassis Expansion CAN Bus Off For symptom byte information, refer to Symptom Byte List .

Diagnostic Fault Information

Circuit/System Description

The GMLAN high speed chassis expansion bus functions the same as the GMLAN high speed bus, and the two buses operate in parallel. The expansion chassis bus was added to reduce message congestion on the primary high speed bus. Since the GMLAN high speed chassis bus and primary GMLAN high speed bus operate in the same manner, the diagnostics for each are the same.

The chassis high speed GMLAN serial data circuits also connect directly to the Data Link Connector (DLC).

Conditions for Running the DTC

The system voltage is between 9 - 16 V.

Conditions for Setting the DTC

The device setting the DTC has attempted to establish communications on the chassis high speed GMLAN serial data circuits more than 3 times.

Action Taken When the DTC Sets

The device suspends all message transmission.

The device uses default values for all parameters received on the serial data circuits. The device inhibits the setting of all other communication DTCs.

DTC U0077 is a type A DTC.

Conditions for Clearing the DTC

A current DTC clears when the malfunction is no longer present.

A history DTC clears when the device ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.

DTC U0077 is a type A DTC.

Diagnostic Aids

Sometimes, while diagnosing a specific customer concern or after a repair, you may notice a history U code present. However, there is no associated "current" or "active" status. Loss of communication U codes such as these can set for a variety of reasons. Many times, they are transparent to the vehicle operator and technician, and/or have no associated symptoms. Eventually, they will erase themselves automatically after a number of fault-free ignition cycles. This condition would most likely be attributed to one of these scenarios:

A device on the data communication circuit was disconnected while the communication circuit is awake.

Power to one or more devices was interrupted during diagnosis.

A low battery condition was present, so some devices stop communicating when battery voltage drops below a certain threshold.

Battery power was restored to the vehicle and devices on the communication circuit did not all re- initialize at the same time.

If a loss of communication U code appears in history for no apparent reason, it is most likely associated with one of the scenarios above. These are all temporary conditions and should never be interpreted as an intermittent fault, causing you to replace a part.

A device may have a U code stored in history that does not require any repairs. Issues with late or corrupted messages between devices can be temporary with no apparent symptom or complaint; this does not mean the device is faulty. Do not replace a device based only on a history U code.

Do not replace a device reporting a U code. The U code identifies which device needs to be diagnosed for a communication issue.

Communication may be available between the device and the scan tool with one or more GMLAN serial data systems inoperative. This condition is due to the device using multiple GMLAN busses.

Use Data Link References to determine what GMLAN serial data communications the non communicating device uses.

The device may not have internal protection for specific control circuits and may open a B+ or ignition fuse. If a fuse is open and the B+ or ignition circuit is not shorted to ground, ensure none of the control circuits are shorted to ground before replacing the non communicating device.

Reference Information

Schematic Reference

Data Communication Schematics Control Module References

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Data Link Communications 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 two or more devices are not communicating on the chassis high speed GMLAN serial data circuit. Refer to Data Link References to determine how many devices should be communicating on the bus.

If only one device is not communicating

Refer to Circuit/System Testing - Testing the Device Circuits.

If two or more devices are not communicating

3. Vehicle OFF, all access doors closed, all vehicle systems OFF, and all keys at least 3 m (9.8 ft) away from vehicle. It may take up to 2 min for all vehicle systems to power down. Disconnect the scan tool from the X84 Data Link Connector. The following tests will be done at the X84 Data Link Connector.

4. 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

5. Vehicle in Service Mode.

6. Test for less than 4.5 V between the serial data circuits listed below and ground.

Terminal 12

Terminal 13

If 4.5 V or greater

Refer to Circuit/System Testing - Testing the Serial Data Circuits for a Short to Voltage.

If less than 4.5 V