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Rear Heated Seat Malfunction (Without CJ4)




Rear Heated Seat Malfunction (Without CJ4)

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.

* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Diagnostic Fault Information






Circuit/System Description

Ground is supplied at all times to the rear seat heating switches located in the auxiliary radio/HVAC controls. When a heated seat switch is pressed, the heated seat switch signal circuit from the body control module is pulled low indicating the heated seat command. The body control module serves as a gateway to transmit the message to the rear seat heating control module via the serial data line. In response to this message, the rear seat heating control module applies battery voltage through the element control circuits to the appropriate seat heating elements. The rear seat heating control module then sends a serial data message back to the body control module to either illuminate or turn off the heated seat indicator.

Reference Information

Schematic Reference

Heated/Cooled Seat Schematics Electrical Diagrams

Connector End View Reference

Component Connector End Views Fuel Pump and Level Sensor Assembly

Description and Operation

Rear Heated Seats Description and Operation Rear Heated Seats

Electrical Information Reference

* Circuit Testing Circuit Testing

* Connector Repairs Connector Repairs

* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections

* Wiring Repairs Wiring Repairs

Scan Tool Reference

Control Module References Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON.

2. Verify the scan tool Body Control Module Left Rear Seat Heating Switch parameter changes between Inactive and Active when pressing the left 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

3. Verify the scan tool Right Rear Heated Seat Switch parameter changes between Inactive and Active when pressing the 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 that both the left and right rear heated seats operate.

• If both the left and right 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 both heated seats operate

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

• If the indicator does not illuminate
Refer to Circuit/System Testing - Rear Seat Heating 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. Ignition OFF, disconnect the harness connector at the appropriate S32 Rear Seat Heating Switch.

2. Ignition ON.

3. Verify a test lamp illuminates between the control circuit terminal 6 and ground.

• If the test lamp does not illuminate

1. Ignition OFF, disconnect the X7 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 ohms in the control circuit end to end.

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

• If less than 2 ohms, replace the K9 Body Control Module.

• If the test lamp illuminates

4. Verify the scan tool Rear Seat Heating Switch parameter is Inactive.

• If not Inactive

1. Ignition OFF, disconnect the X2 harness connector at the K9 Body Control Module.

2. Test for infinite resistance between the signal circuit terminal 2 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 Inactive

5. Install a 3 A fused jumper wire between the signal circuit terminal 2 and ground.

6. Verify the scan tool Rear Seat Heating Switch parameter is Active.

• If not Active

1. Ignition OFF, disconnect the X2 harness connector at the K9 Body Control Module.

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

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

• If less than 1 V

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

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

• If less than 2 ohms, replace the K9 Body Control Module.

• If Active

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

Both Rear Heated Seats are Inoperative

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

1. Ignition OFF and all vehicle systems OFF, disconnect the X2 harness connector at the K29R Rear Seat Heating Control Module. It may take up to 2 minutes for all vehicle systems to power down.

2. Test for less than 10 ohms between the ground circuit terminal 7 and ground.

• If 10 ohms or greater

1. Ignition OFF.

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

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

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

• If less than 10 ohms

3. Ignition ON.

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

* Terminal 2

* Terminal 3

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

1. Ignition OFF.

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

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

• If less than 2 ohms, 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 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 K29R Rear Seat Heating Control Module.

• If the test lamp illuminates

5. Replace the K29R Rear Seat Heating Control Module.

One Rear Heated Seat is Inoperative

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

1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the appropriate E14 Seat Heating Element. It may take up to 2 minutes for all vehicle systems to power down.

2. Test for less than 10 ohms between the ground circuit terminal A and ground.

• If 10 ohms or greater

1. Ignition OFF.

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

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

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

• If less than 10 ohms

3. Connect a test lamp between the control circuit terminal B and ground circuit terminal A, ignition ON.

4. Verify the test lamp turns ON and OFF when commanding the rear heated seat ON and OFF using the appropriate S32 Seat Heating Switch - Left or Right Rear.

• If the test lamp is always OFF

1. Ignition OFF, disconnect the X2 harness connector at the K29R Rear Seat Heating 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 ohms in the control circuit end to end.

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

• If less than 2 ohms, replace the K29R Rear Seat Heating Control Module.

• If the test lamp is always ON

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

• If the test lamp turns ON and OFF

5. Test or replace the E14 Seat Heating Element.

Rear Seat Heating Switch Indicator Circuit Test

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

1. Ignition OFF, disconnect the harness connector at the appropriate S32 Seat Heating Switch - Left or Right Rear, ignition ON.

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

• If the test lamp does not illuminate

1. Ignition OFF, 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 ohms in the control circuit end to end.

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

• If less than 2 ohms, replace the K9 Body Control Module.

• If the test lamp illuminates

3. Connect a test lamp between the control circuit terminal 6 and control circuit terminal 5, ignition ON.

4. Verify the test lamp turns ON and OFF when commanding the Rear Seat Heating Indicator ON and OFF with a scan tool.

• If the test lamp is always OFF

1. Ignition OFF, disconnect the X5 harness connector at the K9 Body Control Module, ignition 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

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

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

• If less than 2 ohms, replace the K9 Body Control Module.

• If the test lamp is always ON

1. Ignition OFF, disconnect the X5 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, replace the K9 Body Control Module.

• If the test lamp turns ON and OFF

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

Component Testing

Rear Seat Heating Switch

1. Ignition OFF, disconnect the harness connector at the appropriate S32 Seat Heating Switch - Left or Right Rear.

2. Test for infinite resistance between the signal terminal 2 and the control terminal 6 with the switch in the open position.

• If less than infinite resistance
Replace the S32 Seat Heating Switch - Rear.

• If infinite resistance

3. Test for less than 2 ohms between the signal terminal 2 and the control terminal 6 with the switch in the closed position.

• If 2 ohms or greater
Replace the S32 Seat Heating Switch - Rear.

• If less than 2 ohms

4. Install a 3 A fused jumper wire between the control circuit terminal 6 and B+. Connect a test lamp between the control terminal 5 and ground.

5. Verify the S32 Seat Heating Switch - Rear temperature indicator illuminates.

• If the indicator does not illuminate
Replace the S32 Seat Heating Switch - Rear.

• If the indicator illuminates

6. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the repair.

* Rear Seat Heater Switch Replacement Rear Seat Heater Switch Replacement

* Rear Seat Back Cushion Heater Replacement (40%) Rear Seat Back Cushion Heater Replacement (40%)Rear Seat Back Cushion Heater Replacement (60%) Rear Seat Back Cushion Heater Replacement (60%)

* Rear Seat Cushion Heater Replacement Rear Seat Cushion Heater Replacement

* Control Module References Control Module References for the K9 Body Control Module and the K29R Rear Seat Heating Control Module replacement, programming and setup

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