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‌ACCESSORIES & EQUIPMENT

Seat Heating and Cooling - Volt

SCHEMATIC WIRING DIAGRAMS

HEATED/COOLED SEAT WIRING SCHEMATICS

Heated Seats (KA1)

Fig. 1: Heated Seats (KA1)

Courtesy of GENERAL MOTORS COMPANY

Heated Seats (KA6)

Fig. 2: Heated Seats (KA6)

Courtesy of GENERAL MOTORS COMPANY

DIAGNOSTIC INFORMATION AND PROCEDURES

DTC B191A OR B191B: FRONT/REAR HEATED SEAT 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.

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

DTC Descriptors

DTC B191A 39

Front Heated Seat Module

DTC B191B 39

Rear Heated Seat Module

Circuit/System Description

An internal fault is detected inside the control module. No external circuits are involved.

Conditions for Running the DTC

Ignition ON.

Conditions for Setting the DTC

The control module detects an internal fault.

Action Taken When the DTC Sets

The seat heating control module will disable all heated seat functions.

Conditions for Clearing the DTC

The DTC clears when the diagnostic runs and passes.

The history DTC will clear after 40 consecutive fault-free ignition cycles have occurred.

Reference Information

Schematic Reference

Heated/Cooled Seat Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Heated Seats Description and Operation

Rear Heated Seats 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

DTC B191A

1. Ignition ON.

2. Verify DTC B191A is not set.

If the DTC is set

Replace the K29F Seat Heating Control Module - Front.

If the DTC is not set

3. All OK.

DTC B191B

1. Ignition ON.

2. Verify DTC B191B is not set.

If the DTC is set

Replace the K29R Seat Heating Control Module - Rear.

If the DTC is not set

3. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Control Module References for K29F Seat Heating Control Module - Front or K29R Seat Heating Control Module - Rear replacement, programming and setup

SYMPTOMS - SEAT HEATING AND COOLING

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

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

There are no DTCs set.

The control module(s) can communicate via the serial data link.

2. Refer to the system description and operation from the following list in order to familiarize yourself with the system functions:

Heated Seats Description and Operation

Rear Heated Seats Description and Operation

Visual/Physical Inspection

Inspect for aftermarket devices which could affect the operation of the power seats. Refer to Checking Aftermarket Accessories .

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

Inspect the seat adjuster track for conditions which may cause binding or objects within the seat adjustment range which obstruct movement or interfere with wiring.

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for

Intermittent Conditions and Poor Connections .

Symptom List

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

Front Heated Seat Malfunction Rear Heated Seat Malfunction

FRONT HEATED SEAT MALFUNCTION

Diagnostic Instructions

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

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

Diagnostic Fault Information

Circuit/System Description

The driver and passenger heated seat switches are located with the HVAC controls. When a heated seat switch is pressed, a LIN bus serial data message is sent from the HVAC controls to the HVAC control module. In turn the HVAC control module sends a low speed GMLAN serial data message to the body control module (BCM) indicating the heated seat command. The BCM serves as the heated seat system master to determine the requested operating mode. The BCM then sends a LIN bus serial data message to the seat heating control module indicating the heated seat command. In response to this message, the seat heating control module attempts to drive the appropriate seat heating elements per the BCM command.

The seat heating control module controls heated seat operation for the driver and passenger seats. When active, power is applied to the seat cushion and back heater elements through a common pulse width modulated (PWM) voltage supply control circuit. Each individual heater element is switched to ground by the module

through a common low side drive control circuit.

The seat back and cushion temperature sensors (thermistors) are packaged with the seat heating elements located just under the seat covers. The seat heating control module supplies each temperature sensor with a 5 V reference signal circuit and a low reference circuit. The module monitors the voltage from the signal circuit to determine the temperature of the seat.

The temperature sensor varies in resistance based on the temperature of the heating element causing the signal voltage to change. Once the module senses the seat reached the set temperature, it will then begin regulate the current flow through the heater elements in order to maintain the desired seat temperature based on the feedback voltage from the sensor.

Diagnostic Aids

A short to ground or B+ in either the heating element voltage control circuit or ground control circuit will cause both the driver and front passenger heated seats to be inoperative.

An open in either the voltage control circuit or ground control circuit between the module and the splice will cause the seat cushion and seat back the heated seat function to be inoperative for that seat.

A short to ground on either the seat cushion or seat back temperature sensor signal circuit will cause the heated seat function to be inoperative for that seat.

An open in either the voltage control circuit or ground control circuit between the splice and the heating element will cause just that one heating element to be inoperative.

The following faults will cause a degraded heated seat operation for both the seat back and seat cushion.

An open or a short to voltage on either the seat cushion or seat back temperature sensor signal circuit.

An open in either the seat cushion or seat back temperature sensor low reference circuit. A fault in either the seat cushion or seat back temperature sensor.

A broken wire in a heating element may cause a degraded heated seat operation for that particular heating element.

When inactive the seat heating control module connects the heating element low side outputs to a common reference point internal to the module which is biased to approximately 3.4 V. The module uses this biased voltage in order to check the high side and low side control circuits for a short to battery or ground before enabling the driver and passenger seat heating elements.

With both the seat cushion and seat back heater elements disconnected, if the high side output of the module is measured it will display a low current bleed off voltage between 3.4 - 12 V. This bleed off voltage does not have a meaningful diagnostic purpose. With one or both of the heater elements connected you would just see the 3.4 V biased voltage from this circuit.

If the heated seats are on high, the temperature level may automatically be lowered after approximately 30 min of operation.

Reference Information

Schematic Reference

Heated/Cooled Seat Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Heated Seats 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 ON.

NOTE: Review the Diagnostic Fault Information table and Diagnostic Aids in order to get a better understanding of the possible heated seat system faults before proceeding Circuit/System Verification and Circuit/System Testing.

2. Verify the scan tool Body Control Module Driver Seat Heating/Venting/Cooling Mode parameter changes between OFF and Seat Back and Cushion Heating when pressing the driver heated seat switch.

If the parameter does not change

Replace the A26 HVAC Controls.

If the parameter changes

3. Verify the scan tool Passenger Seat Heating/Venting/Cooling Mode parameter changes between OFF and Seat Back and Cushion Heating when pressing the passenger heated seat switch.

If the parameter does not change

Replace the A26 HVAC Controls.

If the parameter changes

4. Verify the driver and front passenger heated seats operate.

If the driver and front passenger heated seats are inoperative

Refer to Circuit/System Testing - Both Heated Seats are Inoperative

If the seat cushion and back heating elements are inoperative of one seat

Refer to Circuit/System Testing - One Heated Seat is Inoperative

If just one of the heating elements is inoperative

Refer to Circuit/System Testing - One Heating Element is Inoperative.

If the driver seat exhibits a degraded heated seat operation

Refer to Circuit/System Testing - Degraded Heated Seat Operation Driver Seat

If the passenger seat exhibits a degraded heated seat operation

Refer to Circuit/System Testing - Degraded Heated Seat Operation Passenger Seat

If both heated seats operate

5. All OK.

Circuit/System Testing

Both Heated Seats are Inoperative

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

1. Vehicle OFF, disconnect the X1 harness connector at the K29F Seat Heating Control Module - Front, Vehicle ON.

2. Verify a test lamp illuminates between each B+ circuit terminal listed below and ground. Terminal 7

Terminal 10

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 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 B+ circuit and ground.

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

If infinite resistance, replace the K29F Seat Heating Control Module - Front.

If the test lamp illuminates

3. Vehicle OFF.

4. Test for infinite resistance between each control circuit terminal listed below and ground, one at a time. Terminal 2

Terminal 6

If less than infinite resistance

Repair the short to ground on the circuit.

If infinite resistance

5. Vehicle ON.

6. Test for less than 1 V between each control circuit terminal listed below and ground, one at a time. Terminal 2

Terminal 6

If 1 V or greater

Repair the short to voltage on the circuit.

If less than 1 V

7. Replace the K29F Seat Heating Control Module - Front.

One Heated Seat is Inoperative

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

1. Vehicle OFF, disconnect the X1 harness connector at the K29F Seat Heating Control Module - Front, Vehicle ON.

2. Verify a test lamp illuminates between the B+ circuit terminal 7 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 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 B+ circuit and ground.

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

If infinite resistance, replace the K29F Seat Heating Control Module - Front.

If the test lamp illuminates

3. Vehicle OFF, connect the X1 harness connector at the K29F Seat Heating Control Module - Front. Disconnect the harness connector at the E14 Seat Heating Element - Cushion and the E14 Seat Heating Element - Back, Vehicle ON.

NOTE: When performing this test ensure that you are testing from the correct terminal. Testing from the incorrect terminal will cause a misdiagnosis of the circuit. Three of the four terminals in this connector will not only display a voltage reading but a different voltage reading.

4. Test for 4.8 - 5.2 V between each signal circuit terminal listed below and ground, one at a time. E14 Seat Heating Element - Cushion terminal 2

E14 Seat Heating Element - Back terminal 2

If less than 4.8 V

1. Vehicle OFF, disconnect the X2 harness connector at the K29F Seat Heating Control Module - Front.

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

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

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

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

If less than 2 Ω, replace the K29F Seat Heating Control Module - Front.

If greater than 5.2 V

1. Vehicle OFF, disconnect the X2 harness connector at the K29F Seat Heating Control Module - Front, Vehicle ON.

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

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

If less than 1 V, replace the K29F Seat Heating Control Module - Front.

If between 4.8 - 5.2 V

5. Connect a test lamp between control circuit terminal 1 and control circuit terminal 4 of the E14 Seat Heating Element - Back, Vehicle ON.

NOTE: The test lamp should turn ON for approximately 10 s after the heated seat is commanded ON.

6. Verify the test lamp turns ON after pressing the heated seat switch.

If the test lamp is always OFF

1. Vehicle OFF, remove the test lamp, disconnect the X1 harness connector at the K29F Seat Heating Control Module - Front.

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

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

If less than 2 Ω, replace the K29F Seat Heating Control Module - Front.

If the test lamp turns ON

7. Vehicle OFF, connect the harness connector at the E14 Seat Heating Element - Cushion, Vehicle ON.

8. Verify the test lamp turns ON after pressing the heated seat switch.

If the test lamp is always OFF

NOTE: Because of the type of material used in the heater element, a reliable resistance value is unavailable for a component test.

Test or replace the E14 Seat Heating Element - Cushion.

If the test lamp turns ON

NOTE: Because of the type of material used in the heater element, a reliable resistance value is unavailable for a component test.

9. Test or replace the E14 Seat Heating Element - Back.

One Heating Element is Inoperative

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

1. Vehicle OFF, disconnect the harness connector at the appropriate E14 Seat Heating Element.

2. Connect a test lamp between control circuit terminal 1 and control circuit terminal 4, Vehicle ON.

3. Verify the test lamp turns ON after pressing the heated seat switch.

If the test lamp is always OFF

1. Vehicle OFF, remove the test lamp, disconnect the X1 harness connector at the K29F Seat Heating Control Module - Front.

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

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

If the test lamp turns ON

NOTE: Because of the type of material used in the heater element, a reliable resistance value is unavailable for a component test.

4. Test or replace the E14 Seat Heating Element.

Degraded Heated Seat Operation Driver Seat

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

1. Vehicle OFF, disconnect the harness connector at each component listed below. It may take up to 2 min for all vehicle systems to power down.

E14B Seat Heating Element - Driver Cushion E14A Seat Heating Element - Driver Back

2. Test for less than 40 Ω between each low reference circuit terminal listed below and ground, one at a time.

E14B Seat Heating Element - Driver Cushion terminal 3 E14A Seat Heating Element - Driver Back terminal 3

If 40 Ω or greater

1. Vehicle OFF, disconnect the X2 harness connector at the K29F Seat Heating Control Module - Front.

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

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

If less than 2 Ω, replace the K29F Seat Heating Control Module - Front.

If less than 40 Ω

3. Vehicle ON.

4. Test for 4.8 - 5.2 V between each signal circuit terminal listed below and ground, one at a time. E14B Seat Heating Element - Driver Cushion terminal 2

E14A Seat Heating Element - Driver Back terminal 2

If less than 4.8 V

1. Vehicle OFF, disconnect the X2 harness connector at the K29F Seat Heating Control Module - Front.

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

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

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

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

If less than 2 Ω, replace the K29F Seat Heating Control Module - Front.

If greater than 5.2 V

1. Vehicle OFF, disconnect the X2 harness connector at the K29F Seat Heating Control Module - Front, Vehicle ON.

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

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

If less than 1 V, replace the K29F Seat Heating Control Module - Front.

If between 4.8 - 5.2 V

5. Vehicle OFF, connect the harness connector at the E14B Seat Heating Element - Driver Cushion and the E14A Seat Heating Element - Driver Back. Disconnect the X2 harness connector at the K29F Seat Heating Control Module - Front.

6. Test for 500 Ω - 300 kΩ between the signal circuit and the low reference circuit terminals listed below, one at a time.

E14B Seat Heating Element - Driver Cushion terminal 6 and terminal 1 E14A Seat Heating Element - Driver Back terminal 3 and terminal 1

If not between 500 Ω - 300 kΩ

Replace the E14 Seat Heating Element.

If between 500 Ω - 300 kΩ

7. Replace the K29F Seat Heating Control Module - Front.

Degraded Heated Seat Operation Passenger Seat

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

1. Vehicle OFF, disconnect the harness connector at each component listed below. It may take up to 2 min for all vehicle systems to power down.

E14D Seat Heating Element - Passenger Cushion E14C Seat Heating Element - Passenger Back

2. Test for less than 40 Ω between each low reference circuit terminal listed below and ground, one at a time.

E14D Seat Heating Element - Passenger Cushion terminal 3 E14C Seat Heating Element - Passenger Back terminal 3

If 40 Ω or greater

1. Vehicle OFF, disconnect the X2 harness connector at the K29F Seat Heating Control Module - Front.

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

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

If less than 2 Ω, replace the K29F Seat Heating Control Module - Front.

If less than 40 Ω

3. Vehicle ON.

4. Test for 4.8 - 5.2 V between each signal circuit terminal listed below and ground, one at a time. E14D Seat Heating Element - Passenger Cushion terminal 2

E14C Seat Heating Element - Passenger Back terminal 2

If less than 4.8 V

1. Vehicle OFF, disconnect the X2 harness connector at the K29F Seat Heating Control Module - Front.

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

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

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

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

If less than 2 Ω, replace the K29F Seat Heating Control Module - Front.

If greater than 5.2 V

1. Vehicle OFF, disconnect the X2 harness connector at the K29F Seat Heating Control Module - Front, Vehicle ON.

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

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

If less than 1 V, replace the K29F Seat Heating Control Module - Front.

If between 4.8 - 5.2 V

5. Vehicle OFF, connect the harness connector at the E14D Seat Heating Element - Passenger Cushion and the E14C Seat Heating Element - Passenger Back. Disconnect the X2 harness connector at the K29F Seat Heating Control Module - Front.

6. Test for 500 Ω - 300 kΩ between the signal circuit and the low reference circuit terminals listed below, one at a time.

E14D Seat Heating Element - Passenger Cushion terminal 5 and terminal 2 E14C Seat Heating Element - Passenger Back terminal 4 and terminal 12

If not between 500 Ω - 300 kΩ

Replace the E14 Seat Heating Element.

If between 500 Ω - 300 kΩ

7. Replace the K29F Seat Heating Control Module - Front.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Heater and Air Conditioning User Interface Control Replacement

Refer to Driver or Passenger Seat Back Heater Replacement

Refer to Front Seat Cushion Heater Replacement

Refer to Control Module References for K29F Seat Heating Control Module - Front replacement, programming and setup

REAR HEATED SEAT MALFUNCTION

Diagnostic Instructions

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

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

Diagnostic Fault Information

Circuit/System Description

When a heated seat switch is pressed, the heated seat switch signal circuit from the body control module (BCM) is pulled low indicating the heated seat command. The BCM serves as the heated seat system master to determine the requested operating mode. The BCM then sends a LIN bus serial data message to the rear seat heating control module indicating the heated seat command. In response to this message, the seat heating control module attempts to drive the appropriate seat heating element per the BCM command.

The rear seat heating control module controls heated seat operation for the left and right rear seats. When active, power is applied to the seat cushion heater element through a pulse width modulated (PWM) voltage supply control circuit. The heater element is switched to ground by the module through a low side drive control circuit.

The seat cushion temperature sensor (thermistor) is packaged with the seat heating element located just under the seat cover. The rear seat heating control module supplies the temperature sensor with a 5 V reference signal circuit and a low reference circuit. The module monitors the voltage from the signal circuit to determine the temperature of the seat.

The temperature sensor varies in resistance based on the temperature of the heating element causing the signal voltage to change. Once the module senses the seat reached the set temperature, it will then begin regulate the current flow through the heater elements in order to maintain the desired seat temperature based on the feedback voltage from the sensor.

Diagnostic Aids

A short to ground or B+ in either the heating element voltage control circuit or ground control circuit will cause both rear heated seats to be inoperative.

A short to ground on the seat cushion temperature sensor signal circuit will cause the heated seat function to be inoperative for that seat.

The following faults will cause a degraded heated seat operation.

An open or a short to voltage on the seat cushion temperature sensor signal circuit. An open in the seat cushion temperature sensor low reference circuit.

A fault in the seat cushion temperature sensor.

A broken wire in a heating element may cause a degraded heated seat operation for that particular heating element.

When inactive the seat heating control module connects the heating element low side outputs to a common reference point internal to the module which is biased to approximately 3.5 V. The module uses this biased voltage in order to check the high side and low side control circuits for a short to battery or ground before enabling the left and right rear seat heating elements.

With the seat cushion heater element disconnected, if the high side output of the control module is measured it will display a low current 12 V bleed off voltage. This bleed off voltage does not have a meaningful diagnostic purpose. With the heater elements connected you would just see the 3.5 V biased voltage from this circuit.

If the heated seats are on high, the temperature level may automatically be lowered after approximately 30 min of operation.

Reference Information

Schematic Reference

Heated/Cooled Seat Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

Description and Operation

Rear Heated Seats 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 ON.

NOTE: Review the Diagnostic Fault Information table and Diagnostic Aids in order to get a better understanding of the possible heated seat system faults before proceeding Circuit/System Verification and Circuit/System Testing.

2. Verify the scan tool Body Control Module Left Rear Seat Heating/Venting/Cooling Mode parameter changes between Off and Seat Back and Cushion Heating when pressing the left rear heated seat switch.

If the parameter does not change

Refer to Circuit/System Testing - Heated Seat Switch Circuit Test.

If the parameter changes

3. Verify the scan tool Right Rear Seat Heating/Venting/Cooling Mode parameter changes between Off and Seat Back and Cushion Heating when pressing the right rear heated seat switch.

If the parameter does not change

Refer to Circuit/System Testing - Rear Heated Seat Switch Circuit Test.

If the parameter changes

4. Verify the left and right rear heated seats operate.

If both rear heated seats are inoperative

Refer to Circuit/System Testing - Both Rear Heated Seats are Inoperative

If just one of the rear heated seats is inoperative

Refer to Circuit/System Testing - One Rear Heated Seat is Inoperative

If the left rear seat exhibits a degraded heated seat operation

Refer to Circuit/System Testing - Degraded Heated Seat Operation Left Rear Seat

If the right rear seat exhibits a degraded heated seat operation

Refer to Circuit/System Testing - Degraded Heated Seat Operation Right Rear Seat

If both heated seats operate

5. Verify the rear heated seat switch indicator illuminates after pressing the rear seat heating switch.

If the indicator does not illuminate

Refer to Circuit/System Testing - Heated Seat Switch Indicator Circuit Test.

If the indicator illuminates

6. All OK.

Circuit/System Testing

Rear Heated Seat Switch Circuit Test

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

1. Vehicle OFF and all vehicle systems OFF, disconnect the harness connector at the appropriate S32 Seat Heating Switch - Rear. It may take up to 2 min for all vehicle system to power down.

2. Test for less than 10 Ω between the ground circuit terminal 1 and ground.

If 10 Ω or greater

1. Vehicle OFF.

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

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

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

If less than 10 Ω

3. Vehicle ON.

4. Verify the appropriate scan tool Rear Seat Heating/Venting/Cooling Mode parameter is Off.

If not Off

1. Vehicle OFF, disconnect the X4 harness connector at the K9 Body Control Module.

2. Test for infinite resistance between the signal circuit terminal 3 and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance, replace the K9 Body Control Module.

If Off

5. Install a 3 A fused jumper wire between the signal circuit terminal 3 and the ground circuit terminal 1.

6. Verify the scan tool scan tool Rear Seat Heating/Venting/Cooling Mode parameter is Seat Back and Cushion Heating - High.

If not Seat Back and Cushion Heating - High

1. Vehicle OFF, remove the jumper wire, disconnect the X4 harness connector at the K9 Body Control Module, Vehicle ON.

2. Test for less than 1 V between the signal circuit terminal 3 and ground. If 1 V or greater, repair the short to voltage on the circuit.

If less than 1 V

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

If 2 Ω or greater, repair the open/high resistance in the circuit. If less than 2 Ω, replace the K9 Body Control Module.

If Seat Back and Cushion Heating - High

7. Test or replace the S32 Seat Heating Switch - Rear.

Both Heated Seats are Inoperative

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

1. Vehicle OFF and all vehicle systems OFF, disconnect the X1 harness connector at the K29R Seat Heating

Control Module - Rear, Vehicle ON.

2. Verify a test lamp illuminates between each B+ circuit terminal listed below and ground. Terminal 7

Terminal 10

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 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 B+ circuit and ground.

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

If infinite resistance, replace the K29R Seat Heating Control Module - Rear.

If the test lamp illuminates

3. Vehicle OFF.

4. Test for infinite resistance between each control circuit terminal listed below and ground, one at a time. Terminal 2

Terminal 6

If less than infinite resistance

Repair the short to ground on the circuit.

If infinite resistance

5. Vehicle ON.

6. Test for less than 1 V between each control circuit terminal listed below and ground, one at a time. Terminal 2

Terminal 6

If 1 V or greater

Repair the short to voltage on the circuit.

If less than 1 V

7. Replace the K29R Seat Heating Control Module - Rear.

One Heated Seat is Inoperative

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

1. Vehicle OFF, disconnect the X1 harness connector at the K29R Seat Heating Control Module - Rear, Vehicle ON.

2. Verify a test lamp illuminates between the B+ circuit terminal 7 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 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 B+ circuit and ground.

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

If infinite resistance, replace the K29R Seat Heating Control Module - Rear.

If the test lamp illuminates

3. Vehicle OFF, connect the X1 harness connector at the K29R Seat Heating Control Module - Rear and disconnect the harness connector at the appropriate E14 Seat Heating Element - Rear Cushion, Vehicle ON.

NOTE: When performing this test ensure that you are testing from the correct terminal. Testing from the incorrect terminal will cause a misdiagnosis of the circuit. Three of the four terminals in this connector will not only display a voltage reading but a different voltage reading.

4. Test for 4.8 - 5.2 V between the signal circuit terminal 2 and ground.

If less than 4.8 V

1. Vehicle OFF, disconnect the X2 harness connector at the K29R Seat Heating Control Module - Rear.

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

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

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

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

If less than 2 Ω, replace the K29R Seat Heating Control Module - Rear.

If greater than 5.2 V

1. Vehicle OFF, disconnect the X2 harness connector at the K29R Seat Heating Control Module - Rear, Vehicle ON.

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

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

If less than 1 V, replace the K29R Seat Heating Control Module - Rear.

If between 4.8 - 5.2 V

5. Connect a test lamp between control circuit terminal 1 and control circuit terminal 4, Vehicle ON.

NOTE: The test lamp should turn ON for approximately 20 s after the heated seat

is commanded ON.

6. Verify the test lamp turns ON after pressing the rear heated seat switch.

If the test lamp is always OFF

1. Vehicle OFF, remove the test lamp, disconnect the X1 harness connector at the K29R Seat Heating Control Module - Rear.

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

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

If less than 2 Ω, replace the K29R Seat Heating Control Module - Rear.

If the test lamp turns ON

NOTE: Because of the type of material used in the heater element, a reliable resistance value is unavailable for a component test.

7. Test or replace the E14 Seat Heating Element - Rear Cushion.

Degraded Heated Seat Operation Left Rear Seat

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

1. Vehicle OFF, disconnect the harness connector at the E14F Seat Heating Element - Left Rear Cushion. It may take up to 2 min for all vehicle systems to power down.

2. Test for less than 40 Ω between the low reference circuit terminal 3 and ground.

If 40 Ω or greater

1. Vehicle OFF, disconnect the X2 harness connector at the K29R Seat Heating Control Module - Rear.

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

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

If less than 2 Ω, replace the K29R Seat Heating Control Module - Rear.

If less than 40 Ω

3. Vehicle ON.

4. Test for 4.8 - 5.2 V between the signal circuit terminal 2 and ground.

If less than 4.8 V

1. Vehicle OFF, disconnect the X2 harness connector at the K29R Seat Heating Control Module - Rear.

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

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

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

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

If less than 2 Ω, replace the K29R Seat Heating Control Module - Rear.

If greater than 5.2 V

1. Vehicle OFF, disconnect the X2 harness connector at the K29R Seat Heating Control Module - Rear, Vehicle ON.

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

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

If less than 1 V, replace the K29R Seat Heating Control Module - Rear.

If between 4.8 - 5.2 V

5. Vehicle OFF, connect the harness connector at the E14F Seat Heating Element - Left Rear Cushion and disconnect the X2 harness connector at the K29R Seat Heating Control Module - Rear.

6. Test for 500 Ω - 300 kΩ between the signal circuit terminal 6 and the low reference circuit terminal 1.

If not between 500 Ω - 300 kΩ

Replace the E14F Seat Heating Element - Left Rear Cushion.

If between 500 Ω - 300 kΩ

7. Replace the K29R Seat Heating Control Module - Rear.

Degraded Heated Seat Operation Right Rear Seat

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

1. Vehicle OFF, disconnect the harness connector at the E14H Seat Heating Element - Right Rear Cushion. It may take up to 2 min for all vehicle systems to power down.

2. Test for less than 40 Ω between the low reference circuit terminal 3 and ground.

If 40 Ω or greater

1. Vehicle OFF, disconnect the X2 harness connector at the K29R Seat Heating Control Module - Rear.

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

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

If less than 2 Ω, replace the K29R Seat Heating Control Module - Rear.

If less than 40 Ω

3. Vehicle ON.

4. Test for 4.8 - 5.2 V between the signal circuit terminal 2 and ground.

If less than 4.8 V

1. Vehicle OFF, disconnect the X2 harness connector at the K29R Seat Heating Control Module - Rear.

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

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

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

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

If less than 2 Ω, replace the K29R Seat Heating Control Module - Rear.

If greater than 5.2 V

1. Vehicle OFF, disconnect the X2 harness connector at the K29R Seat Heating Control Module - Rear, Vehicle ON.

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

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

If less than 1 V, replace the K29R Seat Heating Control Module - Rear.

If between 4.8 - 5.2 V

5. Vehicle OFF, connect the harness connector at the E14H Seat Heating Element - Right Rear Cushion and disconnect the X2 harness connector at the K29R Seat Heating Control Module - Rear.

6. Test for 500 Ω - 300 kΩ between the signal circuit terminal 5 and the low reference circuit terminal 2.

If not between 500 Ω - 300 kΩ

Replace the E14H Seat Heating Element - Right Rear Cushion.

If between 500 Ω - 300 kΩ

7. Replace the K29R Seat Heating Control Module - Rear.

Heated Seat Switch Indicator Circuit Test

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

1. Vehicle OFF, disconnect the harness connector at the appropriate S32 Seat Heating Switch - Rear, Vehicle ON.

NOTE: The test lamp in the following step will illuminate at LOW intensity. This is normal circuit operation and does not indicate a circuit malfunction.

2. Verify a test lamp illuminates at LOW intensity between the control circuit terminal 6 and ground.

If the test lamp does not illuminate

1. Vehicle OFF, remove the test lamp, disconnect the X1 harness connector at the K9 Body Control Module.

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

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

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

If 2 Ω or greater, repair the open/high resistance in the circuit. If less than 2 Ω, replace the K9 Body Control Module

If the test lamp illuminates at FULL intensity

1. Vehicle OFF, remove the test lamp, disconnect the X1 harness connector at the K9 Body Control Module, Vehicle ON.

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

If 1 V or greater, repair the short to voltage on the circuit. If less than 1 V, replace the K9 Body Control Module.

If the test lamp illuminates at LOW intensity

3. Connect a test lamp illuminate between control circuit terminal 6 and control circuit terminal 4.

4. Verify the test lamp Does Not illuminate.

If the test lamp illuminates

1. Vehicle OFF, remove the test lamp, disconnect the X5 harness connector at the K9 Body Control Module.

2. Test for infinite resistance between the control circuit terminal 4 and ground. If less than infinite resistance, repair the short to ground on the circuit. If infinite resistance, replace the K9 Body Control Module.

If the test lamp does not illuminate

5. Verify the test lamp illuminates when commanding the Rear Seat Heating Indicator Active with a scan tool.

If the test lamp does not illuminate

1. Vehicle OFF, disconnect the X5 harness connector at the K9 Body Control Module, Vehicle ON.

2. Test for less than 1 V between the control circuit terminal 4 and ground. If 1 V or greater, repair the short to voltage on the circuit.

If less than 1 V

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

If 2 Ω or greater, repair the open/high resistance in the circuit. If less than 2 Ω, replace the K9 Body Control Module.

If the test lamp illuminates

6. Test or replace the S32 Seat Heating Switch - Rear.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Refer to Rear Seat Heater Switch Replacement

Refer to Rear Seat Cushion Heater Replacement

Refer to Control Module References for K29R Seat Heating Control Module - Rear replacement, programming and setup

REPAIR INSTRUCTIONS

WIRE TO WIRE REPAIR - SEATS

Special Tools

EL-38125-10 Splice Sleeve Crimping Tool (non GMNA)

J-38125-5A Ultra Torch Special Tool

J-38125-8 Splice Sleeve Crimping Tool (GMNA)

For equivalent regional tools, refer to Special Tools .

WARNING: In order to reduce the risk of personal injury, loss of high voltage isolation to ground and higher system impedance, do not attempt to repair any HV wiring, connector, or terminal that is damaged. High voltage coaxial type cables are not repairable. Never attempt to repair a coaxial type cable. The entire cable/harness or component must be replaced. In order to maintain system integrity and personal safety, never attempt to repair any high voltage wiring, cables, or terminals. Performing this procedure on high voltage circuits may result in serious injury or death.

NOTE: If the wiring harness internal to the transmission is damaged, the wiring harness must be replaced. The use of splice sleeves in an attempt to repair the internal transmission wires, connectors, or terminals could result in performance issues.

NOTE: Do not splice wires in Door Harness Grommets.

NOTE: The DuraSeal splice sleeves have the following 2 critical features:

A special heat shrink sleeve environmentally seals the splice. The heat shrink sleeve contains a sealing adhesive inside.

A cross hatched (knurled) core crimp provides the necessary low resistance contact integrity for these sensitive, low energy circuits.

Use only DuraSeal splice sleeves to form a one-to-one splice on all types of insulation except high voltage and specialty cables. Use DuraSeal splice sleeves where there are special requirements such as moisture sealing.

Follow the instructions below in order to splice copper wire using DuraSeal splice sleeves.

Splice Sleeve Selection

NOTE: You must perform the following procedures in the listed order. Repeat the procedure if any wire strands are damaged. You must obtain a clean strip with all of the wire strands intact.

1. Open the harness by removing any tape:

Use a sewing seam ripper, available from sewing supply stores, in order to cut open the harness in order to avoid wire insulation damage.

Use the DuraSeal splice sleeves on all types of insulation except Tefzel and coaxial.

Do not use the crimp and DuraSeal splice sleeve to form a splice with more than 2 wires coming together.

2. Cut as little wire off the harness as possible. You may need the extra length of wire in order to change the location of a splice.

Adjust splice locations so that each splice is at least 40 mm (1.5 in) away from the other splices, harness branches, or connectors.

3. Strip the insulation:

When adding a length of wire to the existing harness, use the same size wire as the original wire. Perform one of the following items in order to find the correct wire size:

Find the wire on the schematic and convert to regional wiring gauge size.

If you are unsure of the wire size, begin with the largest opening in the wire stripper and work down until achieving a clean strip of the insulation.

Strip approximately 5.0 mm (0.20 in) of insulation from each wire to be spliced.

Do not nick or cut any of the strands. Inspect the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section.

4. For high temperature wiring, slide a section of high temperature SCT1 shrink tubing down the length of wire to be spliced. Ensure that the shrink tubing will not interfere with the splice procedure.

5. Select the proper DuraSeal splice sleeve according to the wire size. Refer to the above table at the beginning of the repair procedure for the color coding of the DuraSeal splice sleeves and the crimp tool nests.

Fig. 3: Splice Sleeve Crimping Tool With 4 Crimp Nests Courtesy of GENERAL MOTORS COMPANY

6. The EL-38125-10 splice sleeve crimping tool has four crimp nests. The largest crimp nest (4) is used for crimping 10 and 12 gauge wires. The second largest crimp nest (3) is used for crimping 14 and 16 gauge wires. The third largest crimp nest (2) is used for crimping 18 and 20 gauge wires. The smallest crimp nest (1) is used for crimping 22 to 26 gauge wires. The crimp nests are referenced in the table (farther above) under the crimp tool nest color.

Fig. 4: Splice Sleeve Crimping Tool With 3 Crimp Nests Courtesy of GENERAL MOTORS COMPANY

7. The J-38125-8 splice sleeve crimping tool has three crimp nests. The largest crimp nest (3) is used for crimping 10 and 12 gauge wires. The second largest crimp nest (2) is used for crimping 14 and 16 gauge wires. The smallest crimp nest (1) is used for crimping 18 to 20 gauge wires. The crimp nests are referenced in the table (farther above) under the crimp tool nest color.

8. Use the splice sleeve crimp tool in order to position the DuraSeal splice sleeve in the proper color nest of the splice sleeve crimp tool. For the four crimp nest tool, use the three largest crimp nests to crimp the splice sleeves. For the three crimp nest tool, use all three crimp nests to crimp the splice sleeves. Use the four and three crimp tool diagrams (above) and the table (farther above) to match the splice sleeve with the correct crimp nest. The crimp tool diagram callout numbers match the numbers in the table (under crimp tool nest color).

Fig. 5: Identifying DuraSeal Splice Sleeve Courtesy of GENERAL MOTORS COMPANY

9. Place the DuraSeal splice sleeve in the nest. Ensure that the crimp falls midway between the end of the barrel and the stop. The sleeve has a stop (3) in the middle of the barrel (2) in order to prevent the wire (1) from going further. Close the hand crimper handles slightly in order to firmly hold the DuraSeal splice sleeve in the proper nest.

Fig. 6: Crimped DuraSeal Splice Sleeve Courtesy of GENERAL MOTORS COMPANY

10. Insert the wire into the splice sleeve barrel until the wire hits the barrel stop. Refer to Folded-Over Wire Repair for splicing wires of 0.35 mm or less (22, 24, 26 gauge sizes) and for splicing wires of different gauges.

11. Tightly close the handles of the crimp tool until the crimper handles open when released.

The crimper handles will not open until you apply the proper amount of pressure to the DuraSeal splice sleeve. Repeat steps 4 and 6 for the opposite end of the splice.

Fig. 7: Heated Splice Sleeve

Courtesy of GENERAL MOTORS COMPANY

12. Using the heat torch, apply heat to the crimped area of the barrel.

13. Start in the middle and gradually move the heat barrel to the open ends of the tubing: The tubing will shrink completely as the heat is moved along the insulation.

A small amount of sealant will come out of the end of the tubing when sufficient shrinkage is achieved.

Weatherpack™ Wiring Repair

NOTE: Some replacement pigtail connectors may be delivered without the terminated leads installed into the connector. For Weatherpack™ connectors, all terminated leads included in the package should to be installed into the connector. If the connector end view shows that a terminal is not occupied, the extra terminated lead(s) need to be installed and the end(s) sealed using a DuraSeal splice sleeve and taped back into the harness.

1. Insert the wire into the splice sleeve barrel until the wire hits the barrel stop. Refer to Folded-Over Wire Repair for splicing wires of 0.35 mm or less (22, 24, 26 gauge sizes) and for splicing wires of different gauges.

Fig. 8: Tightly Close Handles Of Crimp Tool Courtesy of GENERAL MOTORS COMPANY

2. Tightly close the handles of the crimp tool until the crimper handles open when released.

The crimper handles will not open until you apply the proper amount of pressure to the DuraSeal splice sleeve. Holding the DuraSeal with one hand gently tug on the wire to ensure it is crimped in the DuraSeal.

3. Using the heat torch, apply heat to the crimped area of the barrel.

Fig. 9: Heat To Crimped Area Of Barrel Courtesy of GENERAL MOTORS COMPANY

4. Start in the middle and gradually move the heat barrel to the open ends of the tubing: The tubing will shrink completely as the heat is moved along the insulation.

A small amount of sealant will come out of the end of the tubing when sufficient shrinkage is achieved.

Fig. 10: Taping Extra Terminated Leads Back Into Harness Courtesy of GENERAL MOTORS COMPANY

5. Tape the extra terminated lead(s) back into the harness.

High Temperature Wiring Repairs

Use the following procedures to perform high temperature wiring repairs:

1. Center the high temperature SCT1 shrink tube over the DuraSeal splice sleeve.

2. Using the heat torch, apply heat to the high temperature heat shrink tubing.

3. Gradually move the heat from the center to the open end of the tubing:

The tubing will shrink completely as the heat is moved along the insulation.

A small amount of sealant will come out of the end of the tubing when sufficient shrinkage is achieved.

4. Replace any reflective tape and clips that may have been removed during the repair.

CONNECTOR RECONNECTION - SEATS

Special Tools

EL-35616 Terminal Test Probe Kit

For equivalent regional tools, refer to Special Tools .

When the condition is not currently present, but is indicated in DTC history, the cause may be intermittent. An intermittent may also be the cause when there is a customer complaint, but the symptom cannot be duplicated. Refer to the Symptom Table of the system that is suspect of causing the condition before trying to locate an intermittent condition.

Most intermittent conditions are caused by faulty electrical connections or wiring. Inspect for the following items:

Loose, corroded, or painted terminal stud/fastener Wiring broken inside the insulation

Poor connection between the male and female terminal at a connector A terminal not seated all the way into the connector body

Poor terminal to wire connection - Some conditions which fall under this description are poor crimps, poor solder joints, crimping over the wire insulation rather than the wire itself, and corrosion in the wire to terminal contact area, etc.

Pierced or damaged insulation can allow moisture to enter the wiring causing corrosion. The conductor can corrode inside the insulation, with little visible evidence. Look for swollen and stiff sections of wire in the suspect circuits.

Wiring which has been pinched, cut, or its insulation rubbed through may cause an intermittent open or short as the bare area touches other wiring or parts of the vehicle.

Wiring that comes in contact with hot or exhaust components

Refer to Inducing Intermittent Fault Conditions in order to duplicate the conditions required, in order to verify the customer concern.

Refer to Testing for Electrical Intermittents for test procedures to detect intermittent open, high resistance, short to ground, and short to voltage conditions.

Refer to Scan Tool Snapshot Procedure for advanced intermittent diagnosis and Vehicle Data Recorder operation.

Testing for Terminal Fretting

Some intermittent conditions can be caused by wire terminal fretting corrosion. Fretting corrosion is a build-up of insulating, oxidized wear debris that can form when there is a small motion between electrical contacts. The oxidized wear debris can pile up enough at the electrical contact spots that the electrical resistance across the connection increases. Movement between the contacting surfaces as small as 10 to 100 microns can cause fretting. To put this in perspective, a sheet of paper is about 100 microns thick, so fretting motion is small and hard to see. Vibration and thermal expansion/contraction are the main sources that create fretting motion. Since vehicles vibrate and can experience large temperature swings, they are a good source for fretting motion. Tin, copper, nickel, and iron surfaces are all susceptible to fretting corrosion. Fretting corrosion can be difficult to see but it looks like small, dark smudges on the terminals contact surface.

To correct a fretting condition disconnect the suspect connector and add dielectric grease/lubricant (Nyogel

760G or equivalent, meeting GM specification 9986087) to both sides of the connector terminals. Then reconnect the connector and wipe away any excess lubricant. This will correct the additional terminal contact resistance due to the terminal fretting corrosion.

Testing for Proper Terminal Contact

It is important to test terminal contact at the component and any inline connectors before replacing a suspect component. Mating terminals must be inspected to ensure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation.

Contamination may be caused by the connector halves being improperly connected. A missing or damaged connector seal, damage to the connector itself, or exposing the terminals to moisture and dirt can also cause contamination. Contamination, usually in the underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit.

Deformation is caused by probing the mating side of a connector terminal without the proper adapter. Always use the EL-35616 kit when probing connectors. Other causes of terminal deformation are improperly joining the connector halves, or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact causing an open or intermittently open circuit.

Testing for Proper Terminal Contact in Bussed Electrical Centers

It is very important to use the correct test adapter when testing for proper terminal contact of fuses and relays in a bussed electrical center. Use the EL-35616 kit to test for proper terminal contact. Failure to use the EL-35616 kit can result in improper diagnosis of the bussed electrical center.

Follow the procedure below in order to test terminal contact:

1. Separate the connector halves.

2. Visually inspect the connector halves for contamination. Contamination may result in a white or green build-up within the connector body or between terminals. This causes high terminal resistance, intermittent contact, or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals, and connector body.

3. Using an equivalent male terminal/terminated lead, verify that the retention force is significantly different between a known good terminal and the suspect terminal. Replace the female terminal in question.

Flat Wire Connectors

There are no serviceable parts for flat wire connectors on the harness side or the component side. Follow the procedure below in order to test terminal contact:

1. Remove the component in question.

2. Visually inspect each side of the connector for signs of contamination. Avoid touching either side of the connector as oil from your skin may be a source of contamination as well.

3. Visually inspect the terminal bearing surfaces of the flat wire circuits for splits, cracks, or other imperfections that could cause poor terminal contact. Visually inspect the component side connector to ensure that all of the terminals are uniform and free of damage or deformation.

4. Insert the appropriate adapter into the flat wire harness connector in order to test the circuit in question.

Control Module/Component Voltage and Grounds

Poor voltage or ground connections can cause widely varying symptoms.

Test all control module voltage supply circuits. Many vehicles have multiple circuits supplying voltage to a control module. Other components in the system may have separate voltage supply circuits that may also need to be tested. Inspect connections at the module/component connectors, fuses, and any intermediate connections between the voltage source and the module/component. A test lamp or a DMM may indicate that voltage is present, but neither tests the ability of the circuit to carry sufficient current.

Operate the component to test the ability of the circuit to carry sufficient current. Refer to Circuit Testing

, and Power Distribution Schematics .

Test all control module ground and system ground circuits. The control module may have multiple ground circuits. Other components in the system may have separate grounds that may also need to be tested.

Inspect grounds for clean and tight connections at the grounding point (screw or stud). Inspect the connections at the component and in splice packs, where applicable. Operate the component to test the ability of the circuit to carry sufficient current. Refer to Circuit Testing , and Ground Distribution Schematics .

Temperature Sensitivity

An intermittent condition may occur when a component/connection reaches normal operating temperature. The condition may occur only when the component/connection is cold, or only when the component/connection is hot.

Freeze Frame, Failure Records, Snapshot, or Vehicle Data Recorder data may help with this type of intermittent condition, where applicable.

If the intermittent is related to heat, review the data for a relationship with the following: High ambient temperatures

Underhood/engine generated heat

Circuit generated heat due to a poor connection, or high electrical load Higher than normal load conditions, towing, etc.

If the intermittent is related to cold, review the data for the following:

Low ambient temperatures - In extremely low temperatures, ice may form in a connection or component. Inspect for water intrusion.

The condition only occurs on a cold start.

The condition goes away when the vehicle warms up.

Information from the customer may help to determine if the trouble follows a pattern that is temperature related.

If temperature is suspected of causing an intermittent fault condition, attempt to duplicate the condition.

Refer to Inducing Intermittent Fault Conditions in order to duplicate the conditions required.

Electromagnetic Interference and Electrical Noise

Some electrical components/circuits are sensitive to electromagnetic interference or other types of electrical noise. Inspect for the following conditions:

A mis-routed harness that is too close to high voltage/high current devices such as secondary ignition

components, motors, generator etc. - These components may induce electrical noise on a circuit that could interfere with normal circuit operation.

Electrical system interference caused by a malfunctioning relay, or a control module driven solenoid or switch - These conditions can cause a sharp electrical surge. Normally, the condition will occur when the malfunctioning component is operating.

Installation of non-factory or aftermarket add on accessories such as lights, 2-way radios, amplifiers, electric motors, remote starters, alarm systems, cell phones, etc. - These accessories may create interference in other circuits while operating and the interference would disappear when the accessory is not operating. Refer to Checking Aftermarket Accessories .

Test for an open diode across the A/C compressor clutch and for other open diodes. Some relays may contain a clamping diode.

The generator may be allowing AC noise into the electrical system.

Incorrect Control Module

There are only a few situations where reprogramming a control module is appropriate: A new service control module is installed.

A control module from another vehicle is installed.

Revised software/calibration files have been released for this vehicle.

NOTE: DO NOT re-program the control module with the SAME software/calibration files that are already present in the control module. This is not an effective repair for any type of concern.

Verify that the control module contains the correct software/calibration. If incorrect programming is found, reprogram the control module with the most current software/calibration. Refer to Control Module References for replacement, setup, and programming.

FRONT SEAT HEATER CONTROL MODULE REPLACEMENT

Fig. 11: Front Seat Heater Control Module Courtesy of GENERAL MOTORS COMPANY

DRIVER OR PASSENGER SEAT BACK HEATER REPLACEMENT

Fig. 12: Driver Or Passenger Seat Back Cushion Heater Courtesy of GENERAL MOTORS COMPANY

FRONT SEAT CUSHION HEATER REPLACEMENT

Fig. 13: Front Seat Cushion Heater

Courtesy of GENERAL MOTORS COMPANY

REAR SEAT HEATER SWITCH REPLACEMENT

Fig. 14: Rear Seat Heater Switch

Courtesy of GENERAL MOTORS COMPANY

REAR SEAT HEATER CONTROL MODULE REPLACEMENT

Fig. 15: Rear Seat Heater Control Module Courtesy of GENERAL MOTORS COMPANY

REAR SEAT CUSHION HEATER REPLACEMENT

Fig. 16: Rear Seat Cushion Heater

Courtesy of GENERAL MOTORS COMPANY

DESCRIPTION AND OPERATION

HEATED SEATS DESCRIPTION AND OPERATION

Heated Seat Components

The heated seat system consists of the following components: Heated seat switches

Body control module

Seat heating control module

Driver seat cushion heating element

Driver seat cushion temperature sensor Driver seat back heating element

Driver seat back temperature sensor

Passenger seat cushion heating element

Passenger seat cushion temperature sensor Passenger seat back heating element

Passenger seat back temperature sensor

Heated Seat Switches

The driver and passenger heated seats are controlled by separate heated seat switches located on the center stack near the HVAC controls. The vehicle must be ON to operate the heated seat system. The BCM is the heated seat system master. It monitors heated seat switch activations to determine user requested operating mode. Based on the requested operating mode, the BCM sends a LIN Bus serial data message to the seat heating control module how to drive the self-regulated heating pads. The BCM also controls the indicators used to provide the operator with feedback as to the operating status of the system. With each press of the switch, the system will cycle through High, Medium, Low, and then back to Off again. The BCM also controls the seat temperature and mode indicators, via the serial data line, used to provide the operator with feedback as to the operating status of the system.

Heated Seat Operation

The seat heating control module controls heated seat operation for the driver and passenger seats. When active, power is applied to the seat cushion and back heater elements through a common pulse width modulated (PWM) voltage supply control circuit. Each individual heater element is switched to ground by the module through a common low side drive control circuit.

When inactive the seat heating control module connects the heating element low side outputs to a common reference point internal to the module which is biased to approximately 3.5 V. The module uses this biased voltage in order to check the high side and low side control circuits for a short to battery or ground before enabling the driver and passenger seat heating elements. During heated seat operation, the seat heating control module interrupts control of the heating elements every 10 s for approximately 10 ms to make this biased voltage check.

With both the seat cushion and seat back heater elements disconnected, if the high side output of the module is measured it will display a low current 12 V bleed off voltage. This bleed off voltage does not have a meaningful diagnostic purpose. With one or both of the heater elements connected you would just see the 3.5 V biased voltage from this circuit.

Temperature Regulation

The seat back and cushion temperature sensors (thermistors) are packaged with the seat heating elements located just under the seat covers. The seat heating control module supplies each temperature sensor with a 5 V reference signal circuit and a low reference circuit. The module monitors the voltage from the signal circuit to determine the temperature of the seat.

The temperature sensor varies in resistance based on the temperature of the heating element causing the signal voltage to change. Once the module senses the seat reached the set temperature, it will then begin regulate the current flow through the heater elements in order to maintain the desired seat temperature based on the feedback voltage from the sensor.

If the heated seats are on high, the temperature level may automatically be lowered after approximately 30 min of operation.

REAR HEATED SEATS DESCRIPTION AND OPERATION

Heated Seat Components

The rear heated seat system consists of the following components: Rear heated seat switches

Body control module

Rear seat heating control module

Left rear seat cushion heating element

Left rear seat cushion temperature sensor Right rear seat cushion heating element

Right rear seat cushion temperature sensor

Heated Seat Switches

When a heated seat switch is pressed, the heated seat switch signal circuit from the body control module (BCM) is pulled low indicating the heated seat command. The BCM serves as the heated seat system master to determine the requested operating mode. The BCM then sends a LIN bus serial data message to the rear seat heating control module indicating the heated seat command. In response to this message, the seat heating control module attempts to drive the appropriate seat heating element per the BCM command.

Rear Heated Seat Operation

The rear seat heating control module controls heated seat operation for the left and right rear seats. When active, power is applied to the seat cushion and back heater elements through a common pulse width modulated (PWM) voltage supply control circuit. Each individual heater element is switched to ground by the module through a common low side drive control circuit.

When inactive the rear seat heating control module connects the heating element low side outputs to a common reference point internal to the control module which is biased to approximately 3.5 V. The control module uses this biased voltage in order to check the high side and low side control circuits for a short to battery or ground before enabling either the left or right rear seat heating element. During heated seat operation, the control module interrupts control of the heating elements every 10 s for approximately 10 ms to make this biased voltage check.

Temperature Regulation

The seat cushion temperature sensor (thermistors) is packaged with the seat heating element located just under the seat cover. The rear seat heating control module supplies the temperature sensor with a 5 V reference signal circuit and a low reference circuit. The control module monitors the voltage from the signal circuit to determine

the temperature of the seat.

The temperature sensor varies in resistance based on the temperature of the heating element causing the signal voltage to change. Once the rear seat heating control module senses the seat reached the set temperature, it will then begin regulate the current flow through the heater elements in order to maintain the desired seat temperature based on the feedback voltage from the sensor.

The temperature level may automatically be lowered after approximately 30 min of operation.

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