Front Heated Seat Malfunction (With Memory A45)

Front Heated Seat Malfunction (With Memory A45)

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.

Diagnostic Fault Information







Circuit/System Description

The driver and front passenger heated seats are controlled by separate heated seat switches that are located together with the radio/HVAC control. When a heated seat switch is pressed, a serial data message is sent from the radio/HVAC controls to the HVAC control module indicating the heated seat command. The HVAC control module serves as a gateway to transmit the message to the seat memory control module via the serial data line. In response to this message, the seat memory control module applies battery voltage through the element supply voltage circuit to the appropriate seat heating elements. The seat memory control module then sends a serial data message back to the HVAC control module to gateway the information to the radio/HVAC controls to either illuminate or turn off the appropriate temperature indicator.

Reference Information

Schematic Reference

Heated/Cooled Seat Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Heated/Vented Seat Description and Operation

Electrical Information Reference

- Circuit Testing
- Connector Repairs
- Testing for Intermittent Conditions and Poor Connections
- Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

1. Ignition OFF, disconnect the X4 harness connector at the K40 seat memory control module.
2. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 5 and ground.
3. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
4. Ignition OFF, connect the X4 harness connector at the K40 seat memory control module.
5. Engine ON, observe the scan tool Driver Seat Heating/Venting/Cooling Mode parameter while pressing the driver seat HEAT switch. The reading should change between Off and Back & Cushion.
6. If not the specified value, replace the A20 radio/HVAC control.
7. Check the scan tool Passenger Seat Heating/Venting/Cooling Mode parameter while pressing the passenger seat HEAT switch. The reading should change between Off and Back & Cushion.
8. If not the specified value, replace the A20 radio/HVAC control.
9. If the scan tool parameter readings test normal, there are no DTCs set, and the driver and/or passenger heated seat is inoperative, replace the K40 seat memory control module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
- Radio Control Assembly Replacement
- Control Module References for seat memory control module replacement, setup, and programming