GM Service Manual Online
For 1990-2009 cars only

Diagnostic Fault Information

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Circuit

Short to Ground

Open/High Resistance

Short to Voltage

Signal Performance

Heated Seat Back Only Mode Indicator Control

4

4

4

5

--

Heated Seat Back Only Mode Switch Signal

2

2

2

--

Heated Seat Back/Cushion Indicator Control

4

4

4

5

--

Heated Seat Back/Cushion Switch Signal

1

1

1

--

Heated Seat Cool Indicator Control

4

4

4

5

--

Heated Seat Cool Switch Signal

3

3

3

--

Heated Seat High Temperature Indicator Control

4

4

4

5

--

Heated Seat Low Temperature Indicator Control

4

4

4

5

--

Heated Seat Medium Temperature Indicator Control

4

4

4

5

--

Seat Temperature Control Switch Ground

1

1

--

--

1. Heated seat back/cushion inoperative

2. Heated seat back only mode inoperative

3. Heated seat cool mode inoperative

4. Heated seat switch indicator inoperative

5. Heated seat switch indicator always on

Circuit/System Description

The driver and front passenger climate control seats are controlled by separate heated and cooled seat switches located on the door panels. When a heated or cool seat switch is pressed, ground is momentarily applied through the switch contacts and the switch signal circuit to the driver door module (DDM) or front passenger door module (FPDM). In response to this signal, the door module sends a serial data message to the memory seat module (MSM) indicating the heat or cool seat request. The door module then applies voltage through the appropriate indicator control circuits to the heated seat switch illuminating the appropriate indicators.

Reference Information

Schematic Reference

    •  Driver Seat Schematics
    •  Passenger Seat Schematics

Connector End View Reference

Power Seat Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

    •  Scan Tool Output Controls
    •  Scan Tool Data List
    •  Scan Tool Data Definitions

Circuit/System Verification

Ignition ON, operate the heated and cooled seat switch through all three heat and cool modes of operation. The seat should activate in the appropriate heat or cool modes and the appropriate switch indicators should illuminate until the OFF position is reached.

If any heated or cooled seat mode is inoperative, refer to Heated/Cooled Seats Inoperative.
If the heated and cooled seat operates normal, but the switch indicators do not illuminate or are always ON, refer to the Heated and Cooled Seat Switch Indicator component test. If the switch tests normal, replace the appropriate door module.

Component Testing

Heated and Cool Seat Switch Indicator

  1. Ignition OFF, disconnect the C4 harness connector at the appropriate door module.
  2. Connect a 3A fused jumper wire between the low reference circuit terminal 4 and ground.
  3. Connect a test lamp between B+ and each control circuit terminal listed below. The appropriate indicator should illuminate.
  4. • Seat back only heat mode indicator terminal 11
    • Seat cool mode indicator terminal 12
    • Seat back and cushion heat mode indicator terminal 10
    • Low temperature indicator terminal 9
    • Medium temperature indicator terminal 1
    • High temperature indicator terminal 2
    If any indicator does not illuminate, replace the heated and cooled seat switch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Heated and Cooled Seat Switch Replacement
    •  Control Module References for door control module replacement, setup, and programming