GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2008 🢒 XLR 🢒 Seats 🢒 Seat Heating and Cooling 🢒 Heated/Cooled Seats Inoperative

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

B+, CCSM Terminal D X1

1

1

--

--

Ignition Voltage, CCSM Terminal 15 X2

1

1

--

--

Heated/Cooled Seat Mode Signal, CCSM Terminal 15 X2

1

1

1

--

Seat Blower Voltage Reference

1

1

--

--

Seat Blower Tachometer Signal

1

1

1

--

Seat Blower Speed Control

1

1

1*

--

Seat Blower Low Reference

--

1

--

--

Seat Back Temperature Sensor Signal

1

1

1*

--

Seat Back Temperature Sensor Low Reference

--

1

--

--

Seat Back Heated/Cool Ventilation Module Cool Control

1

1

--

--

Seat Back Heated/Cool Ventilation Module Heat Control

1

1

--

--

Seat Cushion Temperature Sensor Signal

1

1

1*

--

Seat Cushion Temperature Sensor Low Reference

--

1

--

--

Seat Cushion Heated/Cool Ventilation Module Cool Control

1

1

--

--

Seat Cushion Heated/Cool Ventilation Module Heat Control

1

1

--

--

Ground - CCSM

--

1

--

--

* A short B+ will damage the component

1. Heated and cooled seat is inoperative

Circuit/System Description

Battery positive voltage is supplied at all times to the climate control seat modules (CCSM) through the HTD SEAT LH 15A fuse for the driver seat and the HTD SEAT RH 15A fuse for the passenger seat that are located in the IP fuse block. This voltage is used by each module to supply power to the ventilation modules and the blower motor. Each CCSM is also supplied with ignition voltage through the RPA/H/C SEAT/WPR RELAYS 10A fuse located in the body control module (BCM). This voltage is used to power up each module and allows the climate control seat (CCS) system to operate only with the ignition in the ON position. Each CCSM is grounded through the module ground circuit.

Diagnostic Aids
    • In order to perform valid tests when diagnosing the climate control seat system, the ignition must be cycled OFF then ON between each test in order to reset the climate control seat module.
    • A short to ground in the heated/cool ventilation module HEAT control circuit will open the HTDST fuse when the heat mode is selected, and the heat mode will be inoperative. However, when the COOL mode is selected, the system will operate normally.
    • A short to ground in the heated/cool ventilation module COOL control circuit will open the HTDST fuse when the cool mode is selected and the system will be inoperative. However, when the HEAT mode is selected, the system operate normally.

Reference Information

Schematic Reference

Heated/Cooled Seat Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Heated/Cooled 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
  1. Ignition OFF, disconnect the X1 harness connector at the appropriate seat CCSM.
  2. Test for less than 10 ohms between the ground circuit terminal C and ground.
    3. ⇒If greater than the specified range, test the ground circuit for an open/high resistance.
  3. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal D and ground.
    4. ⇒If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
  4. Verify that a test lamp illuminates between the ignition circuit terminal B and ground.
    5. ⇒If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.
  5. Ignition OFF, connect the X1 harness connector at the CCSM and disconnect the X2 harness connector at the CCSM.
  6. Ignition ON, heated/cooled seats OFF, test for approximately 12 volts between the signal circuit terminal 15 and ground.
    7. ⇒If less than the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the HVAC control module.
  7. Observe the voltage from the signal circuit terminal 15 while pressing the seat temperature control switch. The voltage should change state.
    8. ⇒If the voltage did not change state, test the signal circuit for a short to voltage. If the circuit tests normal, replace the HVAC control module.
  8. Test for 0.5-7.5 ohms between control circuit terminal 1 and control circuit terminal 2.
    9. ⇒If greater than the specified range, test the control circuits for an open/high resistance. If the circuits test normal, test or replace the seat cushion heated/cooled ventilation module.
    ⇒If less than the specified range, test for a short between the control circuits. If the circuits test normal, test or replace the seat cushion heated/cooled ventilation module.
  9. Ignition OFF, test for infinite resistance between the signal circuit terminal 18 and ground.
    10. ⇒If not the specified value, test the signal circuit for a short to ground.
  10. Test for 63-18K ohms between the signal circuit terminal 18 and the low reference circuit terminal 17.
    11. ⇒If greater than the specified range, test the signal and low reference circuits for a short to voltage or an open/high resistance. If the circuits test normal, test or replace the seat cushion heated/cooled ventilation module.
    ⇒If less than the specified range, test for a short between the signal and low reference circuits. If the circuits test normal, test or replace the seat cushion heated/cooled ventilation module.
  11. Test for 0.5-7.5 ohms between control circuit terminal 11 and control circuit terminal 12.
    12. ⇒If greater than the specified value, test the control circuits for an open/high resistance. If the circuits test normal, test or replace the seat back heated/cooled ventilation module.
    ⇒If less than the specified range, test for a short between the control circuits. If the circuits test normal, test or replace the seat back heated/cooled ventilation module.
  12. Test for infinite resistance between the signal circuit terminal 19 and ground.
    13. ⇒If not the specified value, test the signal circuit for a short to ground.
  13. Test for 63-18K ohms between the signal circuit terminal 19 and the low reference circuit terminal 20.
    14. ⇒If greater than the specified range, test the signal and low reference circuits for a short to voltage or an open/high resistance. If the circuits test normal, test or replace the seat back heated/cooled ventilation module.
    ⇒If less than the specified range, test for a short between the signal and low reference circuits. If the circuits test normal, test or replace the seat back heated/cooled ventilation module.
  14. Ignition OFF, connect the X2 harness connector at the CCSM and disconnect the harness connector at the heated/cooled seat blower motor.

    15. Important: The ignition must be cycled OFF then ON between each test in order to reset the CCSM.

  15. Ignition OFF then ON, test for 6.0-12.0 volts between the voltage reference circuit terminal 1 and ground.
    16. ⇒If less than the specified range, test the voltage reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the CCSM.
    ⇒If greater than the specified range, test the voltage reference circuit for a short to voltage. If the circuit tests normal, replace the CCSM.

    Important: The ignition must be cycled OFF then ON between each test in order to reset the CCSM.

  16. Ignition OFF then ON, test for 6.0-12.0 volts between the voltage reference circuit terminal 1 and the low reference circuit terminal 4.
    17. ⇒If not the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the CCSM.

    Important: The ignition must be cycled OFF then ON between each test in order to reset the CCSM.

  17. Ignition OFF then ON, test for 1.5-12.0 volts between the control circuit terminal 3 and ground after pressing the seat temperature control switch.
    18. ⇒If less than the specified range, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the CCSM.
    ⇒If greater than the specified range, test the control circuit for a short to voltage. If the circuit tests normal, replace the CCSM.

    Important: The ignition must be cycled OFF then ON between each test in order to reset the CCSM.

  18. Ignition OFF then ON, test for 4.0-16.0 volts between the signal circuit terminal 2 and ground.
    19. ⇒If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the CCSM.
  19. If all circuits test normal, replace the CCSM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Driver Seat Ventilation Heating and Cooling Blower Replacement
    •  Passenger Seat Ventilation Heating and Cooling Blower Replacement
    •  Driver Seat Back Ventilation Heating and Cooling Module Replacement
    •  Driver Seat Cushion Ventilation Heating and Cooling Module Replacement
    •  Passenger Seat Back Ventilation Heating and Cooling Module Replacement
    •  Passenger Seat Cushion Ventilation Heating and Cooling Module Replacement
    •  Control Module References for CCSM and HVAC control module replacement, setup, and programming