GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The driver and passenger seat heaters are controlled by the driver seat module (DSM). Power is supplied to the driver seat cushion and back heater elements through individual voltage supply circuits. Power is supplied to the passenger seat cushion and back heater elements through a common voltage supply circuit. All of the driver and passenger seat heater elements are grounded by the DSM through individual low side drive control circuits. The heater element control circuits are pulse width modulated to ground by the DSM in order to control the seat temperatures by regulating the current flow through the heater elements.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC B3941 Front Seat Heaters Circuit

Conditions for Running the DTC

The system voltage must be between 9-16 volts.

Conditions for Setting the DTC

The DSM determines that one of the seat heater element voltage supply circuits is shorted to ground.

Action Taken When the DTC Sets

    • Both heated seats will be disabled.
    • When the fault is no longer present a history status DTC will be stored, and heated seat operation will be restored.

Conditions for Clearing the DTC

    • The DTC will be current for as long as the fault is present.
    • When the fault is no longer present the DTC will be a history status code.
    • The history DTC will be cleared after 100 error free ignition cycles, or by using the scan tool clearing DTCs feature.

Step

Action

Yes

No

Schematic Reference: Driver Seat Schematics and Passenger Seat Schematics

Connector End View Reference: Power Seat Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

Verify the condition is present.

Does the system operate normally?

Go to Testing for Intermittent Conditions and Poor Connections

Go to Step 3

3

  1. Disconnect the driver seat module (DSM) connectors containing the voltage supply and control circuits to the seat heater elements.
  2. Using a DMM test for continuity to ground at the heater element supply circuit terminals in the harness connectors. Refer to Circuit Testing.

Is continuity to ground present on any of the heater element supply circuits?

Go to Step 4

Go to Step 6

4

  1. Disconnect the affected seat heater element connector.
  2. Test the heater element voltage supply circuit for a short to ground. Refer to Circuit Testing and to Wiring Repairs.

Did you find and correct the condition?

Go to Step 9

Go to Step 5

5

Inspect for poor connections at the seat heater element harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs.

Did you find and correct the condition?

Go to Step 9

Go to Step 7

6

Inspect for poor connections at the DSM harness connectors. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs.

Did you find and correct the condition?

Go to Step 9

Go to Step 8

7

Replace the seat heater element. Refer to Driver or Passenger Seat Back Cushion Heater Replacement or Driver or Passenger Seat Cushion Heater Replacement .

Did you complete the replacement?

Go to Step 9

--

8

Replace the DSM. Refer to Control Module References for replacement, setup, and programming.

Did you complete the replacement?

Go to Step 9

--

9

  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK