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Heated/Cooled Seats Inoperative (KB6)




Heated/Cooled Seats Inoperative (Cadillac, 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 both the driver and passenger seats is controlled by the climate control seat module (CCSM) that is located under the passenger seat. The heated and cooled seat switches are located in the HVAC control module. When a heated or cooled seat switch is pressed a serial data message from the HVAC control module is sent to the memory seat module (MSM) indicating the heat/cool seat request. The MSM then sends a pulse width modulation (PWM) signal through the appropriate heated/cooled seat mode signal circuit to the climate control seat module to activate the heated or cooled seat function. The CCSM then applies battery 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

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 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 may need to be running in order to supply the CCSM with the amount of current needed to operate the heated/cool seat system.
* Examine the seat-to-body inline harness connector under 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. Ignition ON, observe the HVAC control panel while pressing and releasing the appropriate heated or cooled seat switch. The switch symbol should be displayed on the control panel.

• If the symbol is not displayed, replace the HVAC control module.

2. Engine running, operate the driver and passenger heated and cooled seats through the modes of operation listed below. The seat should operate in all three modes.

* Seat back and cushion heat mode
* Back only heat mode
* Cool mode

• If both, the driver and passenger heated/cool seats are inoperative, refer to Both Driver and Passenger Heated/Cooled Seats are Inoperative.
• If just the driver heated/cooled seat is inoperative, refer to Only One Heated/Cooled Seat is Inoperative.
• If just the passenger heated/cooled seat is inoperative, refer to Only One Heated/Cooled Seat is Inoperative.

Circuit/System Testing

Both Driver and Passenger Heated/Cooled Seats are Inoperative

Note: Circuit/System Verification must be performed before 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 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 tests 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.

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

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