Heated/Cooled Seats Inoperative (KB6)
Heated/Cooled Seats Inoperative (Chevrolet or GMC, KB6)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.
Diagnostic Fault Information
Circuit/System Description
The heat and cool seat functions for the 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 lock/window switch. In response to the switch input, the door lock/window switch simultaneously illuminates the appropriate heated/cooled switch indicators and sends a serial data message to the memory seat module (MSM) indicating the heat or cool seat request. The MSM then sends a pulse width modulation (PWM) signal through the appropriate 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 V 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
It is important to review the harness connector end views for the seat ventilation heating and cooling modules before proceeding with Circuit/System Testing. The terminal numbers may not be positioned as expected and could cause a misdiagnosis of the system.
The following conditions must be met 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.
* The engine must be running in order to supply the CCSM with the amount of current needed to operate the heated/cool seat system.
* Inspect the seat-to-body inline harness connector under the affected seat for loose, bent, or backed out terminals.
Reference Information
Schematic Reference
Heated/Cooled Seat Schematics [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views Connector Views
Description and Operation
Heated/Cooled Seats Description and Operation Heated/Cooled Seats
Electrical Information Reference
* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs
Scan Tool Reference
Control Module References Control Module References for scan tool information
Circuit/System Verification
1. If both, the driver and passenger heated and cooled seats are inoperative, refer to Both Driver and Passenger Heated/Cooled Seats are Inoperative.
2. Ignition ON, observe the scan tool Driver Door Switch parameters listed below while pressing and releasing the appropriate switch. The readings should change between Inactive and Active or Off and ON.
* Seat Back Heat Mode Sw.
* Seat Cool Mode Switch
* Seat Heat Mode Sw.
• If the reading does not change between Inactive and Active or Off and ON, refer to the Heated and Cooled Seat Switch component test. If the switch tests normal, replace the driver door lock/window switch.
• If the readings test normal, but the driver heat/cool seat is inoperative, refer to Only One Heated/Cooled Seat is Inoperative.
3. Observe the scan tool Passenger Door Switch parameters listed below while pressing and releasing the appropriate switch. The readings should change between Inactive and Active or Off and ON.
* Seat Back Heat Mode Sw.
* Seat Cool Mode Switch
* Seat Heat Mode Sw.
• If the reading does not change between Inactive and Active or Off and ON, refer to the Heated and Cooled Seat Switch component test. If the switch tests normal, replace the front passenger door lock/window switch.
• If the readings test normal, but the passenger heat/cool seat is inoperative, refer to Only One Heated/Cooled Seat is Inoperative.
4. If all heated and cooled seat functions operate normal, but the heated/cooled seat switch indicators do not illuminate or are always ON, refer to the Heated and Cooled Seat Switch component test. If the switch tests normal, replace the appropriate door lock/window switch.
Circuit/System Testing
Both Driver and Passenger Heated/Cooled Seats are Inoperative
Note: Circuit/System Verification must be performed before proceeding with Circuit/System Testing.
1. Ignition OFF and all vehicle systems OFF, disconnect the X1 harness connector at the CCSM. It may take up to 2 minutes for all vehicle systems to power down.
2. Test for less than 5 ohm between the ground circuit terminal M and ground.
• 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 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.
Only One Heated/Cooled Seat is Inoperative
Note: Circuit/System Verification must be performed before proceeding with Circuit/System Testing.
1. Ignition OFF, disconnect the X3 harness connector at the CCSM.
2. Connect a test lamp between the appropriate signal circuit terminal listed below and B+:
* Driver seat terminal 14
* Passenger seat terminal 6
3. Ignition ON, press the HEAT or COOL seat 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 MSM.
• 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 MSM.
4. Ignition OFF, connect the X3 harness connector to the CCSM and disconnect the harness connector at both the seat cushion and seat back ventilation heating and cooling modules.
5. Ignition OFF and all vehicle systems OFF, it may take up to 2 minutes for all vehicle systems to power down.
Note: Review the harness connector end views for the seat ventilation heating and cooling modules before proceeding with this step. The terminal numbers may not be positioned as expected and could cause a misdiagnosis of the circuit.
6. Test for less than 5 Ohms between each low reference circuit terminal listed below and ground:
* Seat cushion terminal 4
* Seat cushion terminal 8
* Seat back terminal 4
* Seat back terminal 8
• If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit test normal, replace the CCSM.
7. Ignition ON, test for 4.8-5.2 V between each signal circuit terminal listed below and ground:
* Seat cushion terminal 5
* Seat back terminal 5
• 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.
• If greater than the specified range, test the signal circuit for a short to voltage. If the circuit tests normal, replace the CCSM.
Note: The ignition must be cycled OFF for 5 seconds then ON between each test in order to reset the CCSM. This step also requires using a GM approved test lamp (J-35616-210) or equivalent, failure to do so may result in a misdiagnosis of the module.
8. Connect a test lamp between each control circuit terminal listed below and ground one at a time. Turn the ignition OFF for 5 seconds then ignition ON between each test. The test lamp should illuminate or slowly illuminate for approximately 5 seconds after pressing the HEAT switch.
* Seat cushion blower control circuit terminal 2
* Seat cushion blower speed control circuit terminal 7
* Seat back blower control circuit terminal 2
* Seat back blower speed control circuit terminal 7
• If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the CCSM.
• If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the CCSM.
9. Ignition OFF for 5 seconds, ignition ON, connect a test lamp between the seat cushion heat control circuit terminal 1 and ground. The test lamp should illuminate or slowly illuminate for approximately 2-4 seconds after pressing the HEAT switch. The test lamp may exhibit a 4 second delay before it starts to illuminate.
• If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the CCSM.
• If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the CCSM.
10. Ignition OFF for 5 seconds, ignition ON, connect a test lamp between the seat cushion cool control circuit terminal 3 ground. Press the COOL switch. The test lamp should illuminate or slowly illuminate for approximately 2-4 seconds after pressing the COOL switch.
• If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the CCSM.
• If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the CCSM.
11. Ignition OFF, connect the harness connector at the seat cushion ventilation heating and cooling module.
12. Ignition OFF for 5 seconds, ignition ON, connect a test lamp between the seat back heat control circuit terminal 1 and ground. The test lamp should illuminate or slowly illuminate for approximately 2-4 seconds after pressing the HEAT switch. The test lamp may exhibit a 4 second delay before it starts to illuminate.
Note: The functionality of the CCSM does not allow for a clear determination if either the CCSM or the seat cushion ventilation heating and cooling module is at fault.
• If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the seat cushion ventilation heating and cooling module. Repeat Step 12, if the test fails again replace the CCSM.
• If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the CCSM.
13. Ignition OFF for 5 seconds, ignition ON, connect a test lamp between the seat back cool control circuit terminal 3 ground. The test lamp should illuminate or slowly illuminate for approximately 2-4 seconds after pressing the COOL switch.
Note: The functionality of the CCSM does not allow for a clear determination if either the CCSM or the ventilation heating and cooling module is at fault.
• If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the seat cushion ventilation heating and cooling module. Repeat Step 13, if the test fails again replace the CCSM.
• If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the CCSM.
Note: The functionality of the CCSM does not allow for a clear determination for which ventilation heating and cooling module is at fault.
14. If all circuits test normal, replace the seat cushion or seat back ventilation heating and cooling module as required.
Component Testing
Heated and Cooled Seat Switch
1. Ignition OFF, disconnect the X4 harness connector at the appropriate door lock/window switch.
2. Test for infinite resistance between the low reference circuit terminal 4 and the signal terminals listed below the with the switch in the open position.
* Seat back and cushion heat switch terminal 6
* Seat back only mode heat switch terminal 7
* Seat cool switch terminal 3
• If not the specified value, replace the heated and cooled seat switch.
3. Test for less than 2 Ohms between the low reference circuit terminal 4 and the signal terminals listed below with the appropriate switch in the closed position.
* Seat back and cushion heat switch terminal 6
* Seat back only mode heat switch terminal 7
* Seat cool switch terminal 3
• If greater than the specified range, replace the heated and cooled seat switch.
4. Connect a 3 A fused jumper wire between the low reference circuit terminal 4 and ground.
5. Connect a test lamp between B+ and each control terminal listed below. The appropriate indicator should illuminate.
* Seat back only mode indicator terminal 11
* Seat cool mode indicator terminal 12
* Seat back and cushion 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 Verification Tests after completing the repair.
* Driver or Passenger Seat Back Ventilation Heating and Cooling Blower Replacement Driver or Passenger Seat Back Ventilation Heating and Cooling Blower Replacement
* Driver or Passenger Seat Cushion Ventilation Heating and Cooling Blower Replacement Driver or Passenger Seat Cushion Ventilation Heating and Cooling Blower Replacement
* Control Module References Control Module References for the climate control seat module and memory seat module replacement, setup, and programming