The driver and front passenger heated seats are controlled by separate heated seat switches. The switches are located on the door panels. When a heated seat switch is pressed, ground is momentarily applied through the switch contacts and the switch signal circuit to the door module. In response to this signal, the door module then sends a message via the low speed GMLAN serial data line to the memory seat module (MSM) indicating the heat seat request. The door module then applies voltage through the appropriate indicator control circuits to the heated seat switch illuminating the appropriate indicators.

Schematic Reference

Heated/Cooled Seat Schematics

Connector End View Reference

Heated/Cooled Seat Connector End Views

Electrical Information Reference

Scan Tool Reference

Ignition ON, observe the following scan tool parameters in the Driver Door Switch and Passenger Door Switch input data lists while pressing and releasing the related switch. The readings should change between Active and Inactive.

Driver Heated Seat Inoperative

1. Ignition OFF, disconnect the harness connector at the driver heated seat switch.
2. Ignition OFF, test for less than 10 ohms of resistance between the heated seat switch low reference circuit terminal 3 and ground.

⇒	If greater than 10 ohms, test the ground circuit for an open/high resistance. If the circuit tests normal, replace the door module.

3. Ignition ON, verify the scan tool Seat Heat Mode Sw. parameter is Inactive.

⇒	If not Inactive, test the signal circuit terminal 8 for a short to ground. If the circuit tests normal, replace the door control module.

4. Install a 3A fused jumper wire between the signal circuit terminal 8 and ground. Verify the scan tool Seat Heat Mode Sw parameter is Active.

⇒	If not Active, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the door control module.

5. Ignition ON, verify the scan tool Seat Back Heat Mode Sw. parameter is Inactive.

⇒	If not Inactive, test the signal circuit terminal 11 for a short to ground. If the circuit tests normal, replace the door control module.

6. Install a 3A fused jumper wire between the signal circuit terminal 11 and ground. Verify the scan tool Seat Back Heat Mode Sw parameter is Active.

⇒	If not Active, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the door control module.

7. If all circuits test normal, test or replace the heated seat switch.

Passenger Heated Seat Inoperative

1. Ignition OFF, disconnect the harness connector at the passenger heated seat switch.
2. Ignition OFF, test for less than 10 ohms of resistance between the heated seat switch low reference circuit terminal 5 and ground.

⇒	If greater than 10 ohms, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the door module.

3. Ignition ON, verify the scan tool Seat Heat Mode Sw. parameter is Inactive.

⇒	If not Inactive, test the signal circuit terminal 14 for a short to ground. If the circuit tests normal, replace the door control module.

4. Install a 3A fused jumper wire between the signal circuit terminal 14 and ground. Verify the scan tool Seat Heat Mode Sw parameter is Active.

⇒	If not Active, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the door control module.

5. Ignition ON, verify the scan tool Seat Back Heat Mode Sw. parameter is Inactive.

⇒	If not Inactive, test the signal circuit terminal 11 for a short to ground. If the circuit tests normal, replace the door control module.

6. Install a 3A fused jumper wire between the signal circuit terminal 11 and ground. Verify the scan tool Seat Back Heat Mode Sw parameter is Active.

⇒	If not Active, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the door control module.

7. If all circuits test normal, test or replace the heated seat switch.

Driver Heated Seat Switch

1. Ignition OFF, disconnect the harness connector at the heated seat switch.
2. Test for infinite resistance between the following switch signal circuits and the low reference circuit terminal 3 with the switch in the open position.

•	Terminal 8 heated seat back cushion heat switch signal

•	Terminal 11 heated seat back only mode switch signal

⇒	If less than infinite resistance, replace the heated seat switch.

3. Test for less than 2 ohms between the following switch signal circuits and the low reference circuit terminal 3 with the switch in the closed position.

•	Terminal 8 heated seat back cushion heat switch signal

•	Terminal 11 heated seat back only mode switch signal

⇒	If greater than 2 ohms for any of the tests, replace the heated seat switch.

Passenger Heated Seat Switch

1. Ignition OFF, disconnect the harness connector at the heated seat switch.
2. Test for infinite resistance between the following switch signal circuits and the low reference circuit terminal 5 with the switch in the open position.

•	Terminal 14 heated seat back cushion heat switch signal

•	Terminal 11 heated seat back only mode switch signal

⇒	If less than infinite resistance, replace the heated seat switch.

3. Test for less than 2 ohms between the following switch signal circuits and the low reference circuit terminal 5 with the switch in the closed position.

•	Terminal 14 heated seat back cushion heat switch signal

•	Terminal 11 heated seat back only mode switch signal

⇒	If greater than 2 ohms for any of the tests, replace the heated seat switch.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.