GM Service Manual Online
For 1990-2009 cars only

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.

Circuit/System Description

The driver and 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, use a scan tool to observe the appropriate HVAC Control Module heated seat switch parameter listed below while pressing the heated seat switch. The reading should change between Inactive and Active.

    • Driver Heated Seat Sw.
    • Pass. Heated Seat Sw.
If not the specified value, replace the HVAC control module.
If the readings change between Inactive and Active, 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