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, B+ is momentarily applied through the switch contacts and the switch signal circuit to the door lock/window switch. In response to this signal, the door lock/window switch sends a serial data message to the memory seat module (MSM) indicating the heat seat request. The door lock/window switch then illuminates the appropriate heated seat switch indicators.

The left and right heated seats are controlled by the memory seat module (MSM). When active, ground is applied to the seat cushion and back heater elements through a common low side drive low reference control circuit. Battery voltage is applied to the seat cushion and seat back heater elements by the MSM through separate high side drive control circuits. In the back only mode, the MSM applies battery voltage to just the seat back heater element, not the seat cushion heater element. The heater element control circuits are pulse width modulated to B+ by the module in order to control the seat temperature by regulating the current flow through the heater elements. The module then monitors the current flow through the heating elements and the of rate change of the temperature sensors to verify correct 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

Scan Tool Reference

Control Module References for scan tool information

1. Ignition ON, observe the scan tool Driver Door Module and Passenger Door Module heated seat switch parameters listed below while pressing and releasing the appropriate switch. The readings should change between Inactive/Off and Active/On.

•	Heated Seat Switch

•	Back Only Heat Switch

⇒	If not the specified value, replace the appropriate door lock/window switch.

2. Observe the scan tool Driver Seat Module heat zone parameters listed below while pressing the appropriate heated seat switch listed above. The readings should change between Off and Back/Cushion or Back Only.

•	Driver Seat Heat Zone

•	Psgr. Seat Heat Zone

⇒	If not the specified value, replace the MSM.

3. Observe the scan tool Driver Seat Module temperature setting parameters listed below while pressing the appropriate heated seat switch through the high, medium, and low temperature settings. The readings should change between Off, High, Med, and Low.

•	Driver Seat Temp. Setting

•	Psgr. Seat Temp. Setting

⇒	If not the specified values, replace the MSM.

4. Observe the appropriate heated seat switch mode and temperature indicators while pressing the appropriate heated seat switch. The appropriate indicators should illuminate.

⇒	If any of the indicators do not illuminate, replace the appropriate door lock/window switch.

5. If all scan tool parameters test normal, refer to Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the appropriate seat heater element.
2. Connect a test lamp between control circuit terminal A and control circuit terminal B.
3. Ignition ON, press the heated seat switch. The test lamp should illuminate.

⇒	If the test lamp does not illuminate, test the control circuits for a short to ground or an open/high resistance. If the circuits test normal, replace the MSM.

4. If all circuits test normal, test or replace the seat heater element.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.