Battery voltage is supplied at all times to the heated seat module through the HTD/SEAT LT 15A fuse for the driver seat and the HTD/SEAT RT 15A fuse for the passenger seat. Ignition voltage is supplied to the driver and passenger heated seat modules and heated seat switches through the HTD SEAT/ONSTAR IGN 10A fuse located in the underhood fuse block. When the heated seat switch is pressed, battery voltage is applied through the switch contacts and the switch signal circuit to the heated seat module. In response to this signal, the module applies battery voltage through the heater element control circuit to the seat cushion and seat back heater elements for heated seat operation.

Schematic Reference

Heated/Cooled Seat Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Heated Seats Description and Operation

Electrical Information Reference

1. Ignition ON, press the heated seat switch. The seat cushion and seat back should get warm.

⇒	If the heated seat cushion and seat back are both inoperative, refer to Heated Seat Malfunction.

⇒	If just the seat back is inoperative, refer to Seat Back Heater Element Inoperative.

2. Cycle the heated seat switch to the OFF position. The heated seat system should turn OFF.

⇒	If the heated seat remains ON, refer to Heated Seat Malfunction

3. Observe the heated seat switch temperature indicators while pressing the appropriate heated seat switch through the low, medium, and high positions. The appropriate indicators should illuminate as the switch is pressed.

⇒	If the heated seat operates normal, but one or all of the switch temperature indicators are inoperative or always ON, refer to Heated Seat Switch Indicator Malfunction.

Heated Seat Malfunction

1. Ignition OFF, disconnect the X2 harness connector at the center console multifunction switch.
2. Ignition ON, verify that a test lamp illuminates between the Ignition circuit terminal 1 and ground.

⇒	If the test lamp does not illuminate, test the Ignition circuit for a short to ground or an open/high resistance.

3. Ignition OFF, connect the X2 harness connector at the center console multifunction switch and disconnect the harness connector at the appropriate heated seat module.
4. Test for less than 1 Ω between the ground circuit terminal 2 and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

5. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal 10 and ground.

⇒	If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.

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

⇒	If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.

7. Verify that a test illuminates between the signal circuit terminal 9 and ground while pressing the heated seat switch.

⇒	If the test lamp does not illuminate, test the signal circuit for a short to ground or an open/high resistance. If the signal circuit tests normal, test or replace the center console multifunction switch.

8. Test for 2 k - 15 kΩ between the signal circuit terminal 12 and the ground circuit terminal 2.

⇒	If greater than the specified range, test the signal circuit and the ground circuit for a short to voltage or an open/high resistance. If the circuits test normal, test or replace the heated seat element - cushion.

⇒	If less than the specified range, test for a short between the signal circuit and the ground circuit. If the circuits test normal, test or replace the heated seat element - cushion.

9. Test for 1 - 5 Ω between the control circuit terminal 8 and the ground circuit terminal 2.

⇒	If greater than the specified range, test the control circuit and the ground circuit for an open/high resistance. If the circuits test normal, test or replace the heated seat element - cushion.

⇒	If less than the specified range, test for a short between the control circuit and the ground circuit. If the circuits test normal, test or replace the heated seat element - cushion.

10. If all circuits test normal, replace the heated seat control module.

Seat Back Heater Element Inoperative

1. Ignition OFF, disconnect the harness connector at the appropriate heated seat element - back.
2. Test for less than 1 Ω between the ground circuit terminal 3 and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

3. At the seat back heater element, test for 1-8 Ω between terminal 1 and terminal 3.

⇒	If not within the specified range, replace the heated seat element - back.

Heated Seat Switch Indicator Malfunction

1. Ignition ON, heated seats OFF, verify that the appropriate heated seat switch temperature indicators are not illuminated.

⇒	If the indicators are illuminated, test the appropriate control circuit terminal listed below for a short to ground. If the circuit tests normal, replace the appropriate heated seat module.

•	High temperature indicator terminal 5

•	Medium temperature indicator terminal 6

•	Low temperature indicator terminal 11

2. Ignition OFF, disconnect the X2 harness connector at the center console multifunction switch.
3. Ignition ON, verify that a test lamp illuminates between the voltage reference circuit terminal 5 and ground.

⇒	If the test lamp does not illuminate, test the voltage reference circuit for an open/high resistance. If the circuit tests normal, refer to Interior Backlighting Malfunction.

4. Ignition OFF, connect the X2 harness connector at the center console multifunction switch and disconnect the harness connector at the appropriate heated seat module.
5. Ignition ON, connect a test lamp between the appropriate control circuit terminal listed below and ground. The appropriate temperature indicator should illuminate.

•	High temperature indicator terminal 5

•	Medium temperature indicator terminal 6

•	Low temperature indicator terminal 11

⇒	If the appropriate indicator does not illuminate, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, test or replace the center console multifunction switch.

6. If all circuits test normal, replace the heated seat control module.

Center Console Multifunction Switch

1. Ignition OFF, disconnect the X1, X2 harness connectors at the center console multifunction switch.
2. Test for infinite resistance between the B+ terminal 1 X2 and the signal terminals listed below with the switch in the open position.

•	Driver seat switch signal terminal 3 X1

•	Passenger seat switch signal terminal 6 X2

⇒	If not the specified value, replace the center console multifunction switch.

3. Test for less than 2 Ω between the B+ terminal 1 X2 and the signal terminals listed below with the switch in the closed position.

•	Driver seat switch signal terminal 3 X1

•	Passenger seat switch signal terminal 6 X2

⇒	If greater than the specified range, replace the center console multifunction switch.

4. Connect a 3A fused jumper wire between the B+ terminal 1 X2 and battery voltage.
5. Connect a test lamp between each control circuit terminal listed below and ground. The appropriate seat temperature indicator should illuminate.

•	Driver seat high temperature indicator terminal 4 X1

•	Driver seat medium temperature indicator terminal 5 X1

•	Driver seat low temperature indicator terminal 6 X1

•	Passenger seat high temperature indicator terminal 2 X2

•	Passenger seat medium temperature indicator terminal 3 X2

•	Passenger seat low temperature indicator terminal 4 X2

⇒	If the appropriate indicator does not illuminate, replace the center console multifunction switch.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.