Heated/Cooled Seats Inoperative
Heated/Cooled Seats Inoperative
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.
Diagnostic Fault Information
Circuit/System Description
The heat and cool seat functions for both driver and passenger seats are controlled by the climate control seat module (CCSM) that is located under the passenger seat cushion. When a driver or passenger heat or cool seat switch is pressed, a low reference signal is applied through the switch signal circuit to the door control module. In response to the switch input, the door module sends a GMLAN message to the memory seat module (MSM) indicating the heat/cool seat request. The MSM then sends a pulse width modulation (PWM) signal through the heated/cooled seat mode signal circuit to the CCSM. The CCSM then applies battery positive voltage to the seat cushion and seat back thermal electronic devices (TEDs) and a pre-determined voltage to the blower motors. To determine seat temperature, the CCSM supplies a 5 volt signal and a low reference to the temperature sensors that are attached to each TED. The temperature sensors are variable resistors, their resistance changes as the temperature of the seat changes. Then based on the seat temperature, the CCSM controls the voltage level that it applies to the TEDs and blower motors.
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 CCSM.
* Most circuit faults will set a DTC within 1.5 minutes. However, some circuit faults may cause a performance problem in one mode and be inoperative and set a DTC in another mode. In some cases it may take 5 minutes or more for a DTC to set. Operate the heated/cooled seat in each of the three modes for 5 minutes or more then check for DTCs.
Reference Information
Schematic Reference
Heated/Cooled Seat Schematics (Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Heated/Cooled Seats Description and Operation (Heated/Cooled Seats Description and Operation)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
Scan Tool Reference
Programming and Relearning (Programming and Relearning) for Scan Tool Information
Circuit System Verification
1. If both the driver and passenger heated and cooled seats are inoperative, refer to Driver and Passenger Heated/Cool Seats Inoperative.
2. Ignition ON, observe the following scan tool Driver Door Switch parameters while pressing and releasing the related switch. The readings should change between Inactive and Active.
* Seat Heat Mode Sw.
* Seat Back Heat Mode Sw.
* Seat Cool Mode Switch.
• If not Active or always Active, refer to the Heated and Cooled Seat Switch Component Test.
3. Ignition ON, operate the driver heated/cooled seat in each of the three modes for more than 1.5 minutes each, then verify that no DTCs are set.
• If DTCs are displayed, refer to Diagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code Descriptions) .
• If the driver heated and cooled seat is inoperative, refer to Driver Heated/Cooled Seat Inoperative.
4. Ignition ON, observe the following scan tool Passenger Door Switch parameters while pressing and releasing the related switch. The readings should change between Inactive and Active.
* Seat Heat Mode Sw.
* Seat Back Heat Mode Sw.
* Seat Cool Mode Switch.
• If not Active or always Active, refer to the Heated and Cooled Seat Switch Component Test.
5. Ignition ON, operate the passenger heated/cooled seat in each of the three modes for more than 1.5 minutes each, then verify that no DTCs are set.
• If DTCs are displayed, refer to Diagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code Descriptions) .
• If the passenger heated and cooled seat is inoperative, refer to Passenger Heated/Cooled Seat Inoperative.
Circuit/System Testing
Driver and Passenger Heated/Cool Seats Inoperative
1. Ignition OFF, disconnect the X1 harness connector at the CCSM.
2. Ignition OFF, test for less than 5 ohms of resistance between the ground circuit terminal M and ground.
• If greater than 5 ohms, test the ground circuit for an open/high resistance.
3. Verify that a test lamp illuminates between the B+ circuit terminal E and ground.
• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
4. Ignition OFF, disconnect the X2 harness connector at the CCSM.
5. Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 1 and ground.
• If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.
6. If all circuits test normal, replace the CCSM.
Driver Heated/Cooled Seat Inoperative
1. Ignition OFF, disconnect the X3 harness connector at the CCSM.
2. Connect a test lamp between the signal circuit terminal 14 and B+.
3. Ignition ON, press the HEAT or COOL switch through the high, medium, and low positions to OFF. The test lamp should illuminate until the OFF position is reached.
• If the test lamp does not illuminate, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the memory seat module.
• If the test lamp is ON with the switch in the OFF position, test the signal circuit for a short to ground. If the circuit tests normal, replace the memory seat module.
4. Ignition OFF, connect the X3 harness connector at the CCSM.
5. Disconnect the harness connector at the seat cushion ventilation heat and cool module.
6. Ignition ON, verify that a test lamp illuminates between the control circuits listed below and ground, while commanding the related Driver Seat Heat Cmd. and the Driver Seat Cool Cmd. ON and OFF with a scan tool.
* Seat cushion heat control circuit terminal 1
* Seat cushion cool control circuit terminal 3
• If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the climate control seat module.
• If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the climate control seat module.
7. Ignition OFF, connect the harness connector at the seat cushion ventilation heat and cool module.
8. Disconnect the harness connector at the seat back ventilation heat and cool module.
9. Ignition ON, verify that a test lamp illuminates between the control circuits listed below and ground, while commanding the related Driver Seat Heat Cmd. and the Driver Seat Cool Cmd. ON and OFF with a scan tool.
* Seat back heat control circuit terminal 1
* Seat back cool control circuit terminal 3
• If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the climate control seat module.
• If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the climate control seat module.
Passenger Heated/Cooled Seat Inoperative
1. Ignition OFF, disconnect the X3 harness connector at the CCSM.
2. Connect a test lamp between the signal circuit terminal 6 and B+.
3. Ignition ON, press the HEAT or COOL switch through the high, medium, and low positions to OFF. The test lamp should illuminate until the OFF position is reached.
• If the test lamp does not illuminate, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the memory seat module.
• If the test lamp is ON with the switch in the OFF position, test the signal circuit for a short to ground. If the circuit tests normal, replace the memory seat module.
4. Ignition OFF, connect the X3 harness connector at the CCSM.
5. Disconnect the harness connector at the seat cushion ventilation heat and cool module.
6. Ignition ON, verify that a test lamp illuminates between the control circuits listed below and ground while commanding the related Passenger Seat Heat Cmd. and the Passenger Seat Cool Cmd. ON and OFF with a scan tool.
* Seat cushion heat control circuit terminal 1
* Seat cushion cool control circuit terminal 3
• If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the climate control seat module.
• If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the climate control seat module.
7. Ignition OFF, connect the harness connector at the seat cushion ventilation heat and cool module.
8. Disconnect the harness connector at the seat back ventilation heat and cool module.
9. Ignition ON, verify that a test lamp illuminates between the control circuits listed below and ground, while commanding the related Passenger Seat Heat Cmd. and the Passenger Seat Cool Cmd. ON and OFF with a scan tool.
* Seat back heat control circuit terminal 1
* Seat back cool control circuit terminal 3
• If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the climate control seat module.
• If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the climate control seat module.
Component Testing
Heated and Cool Seat Switch
1. Ignition OFF, disconnect the X4 harness connector at the door module.
2. Test for infinite resistance between the following switch signal circuits and the low reference circuit terminal 4 with the switch in the open position.
* Terminal 7 heated seat back only mode switch signal
* Terminal 6 heated seat back cushion heat switch signal
* Terminal 3 heated seat cool switch signal
• If less than infinite resistance, replace the heated and cooled seat switch.
3. Test for less than 2 ohms between the following switch signal circuits and the low reference circuit terminal 4 with the switch in the closed position.
* Terminal 7 heated seat back only mode switch signal
* Terminal 6 heated seat back cushion heat switch signal
* Terminal 3 heated seat cool switch signal
• If greater than 2 ohms for any of the tests, replace the heated and cooled seat switch.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Heated and Cooled Seat Switch Replacement (Service and Repair)
* Programming and Relearning (Programming and Relearning) for CCSM and MSM replacement, setup, and programming