GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2008 🢒 DTS 🢒 Seats 🢒 Seat Heating and Cooling 🢒 Rear Seat Heater Switch Indicator Malfunction

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

Rear Heated Seat Switch Ground

1

1

--

--

Rear Heated Seat Switch Indicator Supply Voltage

3

3

--

--

Rear Heated Seat Back Only Mode Indicator Control

4

3

3

--

Rear Heated Seat Back Only Mode Switch Signal

2

2

2

--

Rear Heated Seat Back/Cushion Indicator Control

4

3

3

--

Rear Heated Seat Low Temperature Indicator Control

4

3

3

--

Rear Heated Seat Medium Temperature Indicator Control

4

3

3

--

Rear Heated Seat High Temperature Indicator Control

4

3

3

--

Rear Heated Seat Back Cushion Switch Signal

1

1

1

--

1. Rear heated seat inoperative

2. Rear heated seat back only mode inoperative

3. Rear heated seat switch indicator inoperative

4. Rear heated seat switch indicator always on

Circuit/System Description

The left and right rear passenger heated seats are controlled by separate heated seat switches. The switches are located on the rear door panels. When a heated seat switch is pressed, ground is momentarily applied through the switch contacts and the switch signal circuit to the rear heated seat module (RHSM). In response to this signal, the RHSM applies battery voltage through the element supply voltage circuits to the seat cushion and seat back heating elements. The RHSM then supplies a ground through the appropriate indicator control circuits to the heated seat switch illuminating the appropriate indicators.

Reference Information

Schematic Reference

Heated/Cooled Seat Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Rear 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 Testing

Rear Heated Seat Switch Indicators Inoperative

  1. Ignition OFF, disconnect the harness connector at the heated seat switch.
  2. Ignition ON, verify that a test lamp illuminates between the supply voltage circuit terminal K and ground.
    3. ⇒If the test lamp does not illuminate, test the supply voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the body control module (BCM).
  3. Ignition OFF, connect the harness connector at the heated seat switch.
  4. Disconnect the X3, X4 harness connectors at the RHSM.
  5. Ignition ON, connect a test lamp between the control circuits listed below and ground. The appropriate indicator should illuminate.
    6. • Seat back and cushion mode indicator terminal 17 X4
    • Seat back only mode indicator terminal 15 X4
    • Low heat indicator terminal 5 X3
    • Medium heat indicator terminal 16 X4
    • High heat indicator terminal 4 X3
    ⇒If any indicator does not illuminate, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, test or replace the heated seat switch.
  6. If all circuits test normal, replace the RHSM.

Heated Seat Switch Indicators Always On

  1. Ignition OFF, disconnect the X3, X4 harness connectors at the RHSM.
  2. Ignition ON, heated seats OFF, the heated seat switch mode indicators should not be illuminated.
    3. ⇒If illuminated, test the appropriate control circuit listed below for a short to ground. If the circuit tests normal, test or replace the heated seat switch.
    • Seat back and cushion mode indicator terminal 17 X4
    • Seat back only mode indicator terminal 15 X4
    • Low heat indicator terminal 5 X3
    • Medium heat indicator terminal 16 X4
    • High heat indicator terminal 4 X3
  3. If all circuits test normal, replace the RHSM.

Component Testing

Rear Heated Seat Switch

  1. Ignition OFF, disconnect the harness connector at the heated seat switch switch.
  2. Test for infinite resistance between the signal terminal G and the ground terminal J with the seat back and cushion mode switch in the open position.
    3. ⇒If not the specified value, replace the heated seat switch switch.
  3. Test for infinite resistance between the signal terminal A and the ground terminal J with the seat back only mode switch in the open position.
    4. ⇒If not the specified value, replace the heated seat switch switch.
  4. Test for less than 2 ohms between the signal terminal G and the ground terminal J with the seat back and cushion mode switch in the closed position.
    5. ⇒If greater than the specified range, replace the heated seat switch.
  5. Test for less than 2 ohms between the signal terminal A and the ground terminal J with the seat back only mode switch in the closed position.
    6. ⇒If greater than the specified range, replace the heated seat switch.
  6. Connect a 3A fused jumper wire between the B+ terminal K and battery voltage.
  7. Connect a test lamp between the control circuits listed below and ground. The selected indicator should illuminate.
    8. • Seat back only mode indicator terminal B
    • Low heat indicator terminal C
    • Medium heat indicator terminal D
    • High heat indicator terminal E
    • Seat back cushion mode indicator terminal H
    • Terminal H seat back cushion mode indicator
         ⇒If any of the indicators do not illuminate, replace the rear heated seat switch.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Rear Seat Heater Switch Replacement
    •  Control Module References for RHSM and BCM replacement, setup, and programming