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Front Heated Seat Malfunction (With Memory)

Front Heated Seat Malfunction (With Memory)

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 Short to Ground Open/High Resistance Short to Voltage Signal Performance
Seat Memory Control Module B+ Terminal 5 X4

B242A 02, B2425 0D, B2430 0D, 1, 2

B242A 02, B2425 0D, B2430 0D, 1, 2

-

-

Driver Heated Seat Element Control Terminal 11 X3

B242A 02

B2425 0D

B242A 01

B2425 0B, B2425 0E

Driver Heated Seat Element Control Terminal 6 X3

B242A 02

B2425 0D

B242A 01

B2425 0B, B2425 0E

Driver Heated Seat Temperature Sensor Signal

B1925 02

B1925 05

B1925 05

-

Driver Heated Seat Temperature Sensor Low Reference

-

B1925 05

-

-

Passenger Heated Seat Element Control Terminal 10 X3

B242A 02

B2430 0D

B242A 01

B2430 0B, B2430 0E

Passenger Heated Seat Element Control Terminal 4 X3

B242A 02

B2430 0D

B242A 01

B2430 0B, B2430 0E

Passenger Heated Seat Temperature Sensor Signal

B2170 02

B2170 05

B2170 05

-

Passenger Heated Seat Temperature Sensor Low Reference

-

B2170 05

-

-

1. Power seats inoperative

2. Heated seats inoperative



Circuit/System Description

The driver and passenger heated seats are controlled by separate heated seat switches located in the HVAC control. When a seat heating switch is pressed, a serial data message is sent from the HVAC control to the HVAC control module. The HVAC control module serves as a gateway to transmit the message to the seat memory control module via the serial data line, which provides the order for seat heating. In response to this message, the seat memory control module then 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 HVAC control 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 HEATED seat switch. The reading should change between Off and Back & Cushion Heat.

6. If not the specified value, replace the A26 HVAC control.

7. Observe the scan tool Passenger Seat Heating/Venting/Cooling Mode parameter while pressing the passenger HEATED seat switch. The reading should change between Off and Back & Cushion Heat.

8. If not the specified value, replace the A26 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.


• Heater and Air Conditioning Control Replacement

• Control Module References for seat memory control module replacement, setup, and programming