For 1990-2009 cars

### 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
--- | --- | --- | --- | ---
Driver Heated Seat Element Supply Voltage | B2345 00, B2508 02 | B2425 0C, B2425 0D | B2345 00, B2508 01 | --
Driver Heated Seat Element Control | B2345 00, B2508 02 | B2425 0C, B2425 0D | B2345 00, B2508 01 | --
Driver Heated Seat Temperature Sensor Signal | B1925 02 | B1925 05, B2425 04, B2425 1F | B1925 05, B2425 04, B2425 1F | B2345 13, B2345 42, B2345 4B
Driver Heated Seat Temperature Sensor Low Reference | -- | B1925 05, B2425 04, B2425 1F | -- | B2345 13, B2345 42, B2345 4B
Passenger Heated Seat Element Supply Voltage | B2345 00, B2508 02 | B2430 0C, B2430 0D | B2345 00, B2508 01 | --
Passenger Heated Seat Element Control | B2345 00, B2508 02 | B2430 0C, B2430 0D | B2345 00, B2508 01 | --
Passenger Heated Seat Temperature Sensor Signal | B2170 02 | B2170 05, B2430 04, B2430 1F | B2170 05, B2430 04, B2430 1F | B2345 13, B2345 42, B2345 4B
Passenger Heated Seat Temperature Sensor Low Reference | -- | B2170 05, B2430 04, B2430 1F | -- | B2345 13, B2345 42, B2345 4B

### Circuit/System Description

The driver and front passenger heated seats are controlled by separate heated seat switches. Both switches are located in the climate control panel (CCP). When a heated seat switch is pressed, the CCP sends a serial data message to the heated seat module (HSM) indicating the heated seat request. In response to this signal, the HSM activates the heated seat by applying battery voltage to the seat heating elements. The HSM then sends a serial data message back to the CCP commanding it to illuminate the appropriate seat temperature indicator.

### Reference Information

#### 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

• | 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 Verification

Ignition ON, observe the appropriate scan tool Heated Seat Module parameter listed below while pressing the heated seat switch. The reading should change between Off and Back and Cushion.

• | Driver Seat HVC Mode

• | Passenger Seat HVC Mode

⇒ | If not the specified value, replace the HVAC control module.

⇒ | If the parameter reading is Back and Cushion, the heated seat is inoperative, and there are NO DTCs set, replace the HSM.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for HVAC control module and HSM replacement, setup, and programming