Diagnostic Fault Information
Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Battery Positive Voltage | 1 | 1 | -- | -- |
Ignition 3 Voltage | 1 | 1 | -- | -- |
Driver/Passenger Seat Blower Supply Voltage | 2 | 2 | -- | -- |
Left Heated/Cooled Seat Mode Signal | 2 | 2 | 2 | -- |
Right Heated/Cooled Seat Mode Signal | 2 | 2 | 2 | -- |
Heated Seat Back Only Mode Switch Signal | 5 | 5 | 5 | -- |
Heated Seat Cool Switch Signal | 4 | 4 | 4 | -- |
Heated Seat Back Cushion Switch Signal | 3 | 3 | 3 | -- |
Seat Back Temperature Sensor Signal | 2 | 2 | 2 | -- |
Seat Cushion Temperature Sensor Signal | 2 | 2 | 2 | -- |
Seat Back Heated/Cool Ventilation Module Cool Control | 1 | 2 | -- | -- |
Seat Back Heated/Cool Ventilation Module Heat Control | 1 | 2 | -- | -- |
Seat Cushion Heated/Cool Ventilation Module Cool Control | 1 | 2 | -- | -- |
Seat Cushion Heated/Cool Ventilation Module Heat Control | 1 | 2 | -- | -- |
Seat Back Blower Speed Control | 2 | 2 | 6 | -- |
Seat Cushion Blower Speed Control | 2 | 2 | 6 | -- |
Heated Seat Switch Low Reference | -- | 2 | -- | -- |
Seat Blower Low Reference | -- | 2 | -- | -- |
Seat Back Temperature Sensor Low Reference | -- | 2 | -- | -- |
Seat Cushion Temperature Sensor Low Reference | -- | 2 | -- | -- |
Module Ground | -- | 1 | -- | -- |
1. Driver and passenger heated/cooled seats are inoperative 2. Seat heat and cool modes are inoperative 3. Seat heat mode is inoperative 4. Seat cool mode is inoperative 5. Heated/cooled seat inoperative - Back Only Mode 6. Heated/cooled seats temperature adjustment is inoperative or the blower is always On | ||||
Circuit/System Description
The heat and cool seat functions for both driver and passenger seats are controlled by the climate control seat module 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 climate control seat (CCS) module. The CCS module 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 CCS module 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 CCS module 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 CCS system, the ignition must be cycled OFF then ON between each test in order to reset the CCS module. |
| • | A short to battery voltage on a temperature sensor signal circuit may open the sensor. |
Reference Information
Schematic Reference
Connector End View Reference
Power Seat Connector End Views
Electrical Information Reference
Scan Tool Reference
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the appropriate seat cushion or seat back ventilation heat and cool module.
- Connect a test lamp between the control circuit terminal 7 and ground.
- Ignition ON, press the HEAT switch. The test lamp should illuminate or slowly illuminate for approximately 5 seconds.
- If all circuits test normal, replace the CCS module.
Important: The ignition must be cycled OFF then ON between each test in order to reset the CCS module.
| ⇒ | If the test lamp does not illuminate, test the control circuit for an open/high resistance. If the circuit tests normal, replace the CCS module. |
| ⇒ | If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the CCS module. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for CCS module replacement, setup, and programming.
