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 B X1 | 1 | 1 | -- | -- |
B+, Driver Seat Back Blower Motor | 2 | 4 | -- | -- |
B+, Driver Seat Cushion Blower Motor | 2 | 5 | -- | -- |
B+, Passenger Seat Back Blower Motor | 1 | 8 | -- | -- |
B+, Passenger Seat Cushion Blower Motor | 1 | 9 | -- | -- |
Ignition Voltage | 1 | 1 | -- | -- |
Driver Heated/Vented Seat Mode Serial Data Signal | 2 | 2 | 2 | -- |
Driver Seat Cushion Temperature Sensor Signal | 2 | 2 | 2 | -- |
Driver Seat Cushion Temperature Sensor Low Reference | -- | 2 | -- | -- |
Driver Seat Back and Cushion Blower Motor Control | 2 | 2 | 3 | -- |
Driver Seat Back Blower Motor Control | 2 | 4 | 3 | -- |
Driver Seat Cushion Blower Motor Control | 2 | 5 | 3 | -- |
Driver Seat Back Blower Motor Ground | -- | 4 | -- | -- |
Driver Seat Cushion Blower Motor Ground | -- | 5 | -- | -- |
Passenger Heated/Vented Seat Mode Serial Data Signal | 6 | 6 | 6 | -- |
Passenger Seat Cushion Temperature Sensor Signal | 6 | 6 | 6 | -- |
Passenger Seat Cushion Temperature Sensor Low Reference | -- | 6 | -- | -- |
Passenger Seat Back and Cushion Blower Motor Control | 6 | 6 | 7 | -- |
Passenger Seat Back Blower Motor Control | 6 | 8 | 7 | -- |
Passenger Seat Cushion Blower Motor Control | 6 | 9 | 7 | -- |
Passenger Seat Back Blower Motor Ground | -- | 8 | -- | -- |
Passenger Seat Cushion Blower Motor Ground | -- | 9 | -- | -- |
Low Reference - Driver and Passenger Seat Cushion Temperature Sensors | -- | 1 | -- | -- |
Ground - Climate Control Seat Module | -- | 1 | -- | -- |
1. Driver and passenger heated/vented seats are inoperative 2. Driver vented seat is inoperative 3. Driver vented seat is always ON 4. Driver vented seat back is inoperative 5. Driver vented seat cushion is inoperative 6. Passenger vented seat is inoperative 7. Passenger vented seat is always ON 8. Passenger vented seat back is inoperative 9. Passenger vented seat cushion is inoperative | ||||
Circuit/System Description
Battery voltage is supplied to the climate control seat module (CCSM) from the IGN 3 fuse located in the left rear fuse block. This voltage is used to power up the CCSM allowing the heated/vented seats to operate only when the ignition switch is in the ON position. Battery positive voltage is supplied at all times to the driver seat blower motors from the MSM Fuse located in the left rear fuse block. Battery positive voltage is also supplied at all times to the passenger seat blower motors from the RF HTD/SEATS/XM Fuse located in the right rear fuse block. Both, the driver seat and passenger seat blower motors are grounded through their ground circuits and G307. When a cooled seat switch is pressed, a serial data message is sent from the HVAC control module to the memory seat module (MSM) indicating the cool seat request. The MSM then sends a PWM serial data signal to the CCSM indicating the cool seat command. The CCSM sends a high side pulse width modulation (PWM) signal through the blower motor control circuits to the seat cushion and seat back blower motors indicating the cooled seat command. In response to this signal, the logic in the blower motors set the blower speed to the switch set point. Both blower motors then run drawing cabin air around and away from occupant.
Diagnostic Aids
When performing resistance measurements on the heated seat system, make sure the seats are cooled. If the seat heating elements are still warm, resistance readings may be affected.
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Heated/Vented Seat Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit System Verification
- Ignition ON, with a scan tool, observe the vented seat switch parameters listed below while pressing and releasing the appropriate switch. The readings should change between Inactive and Active.
- Ignition ON, turn ON the driver and passenger vented seats to the high cool position. The driver and passenger vented seats should cool when commanded ON.
| • | Driver Seat Vent Sw. |
| • | Psgr. Seat Vent Sw. |
| ⇒ | If the readings do not change between the specified values, replace the HVAC control module. |
| ⇒ | If the vented seat function is inoperative for both front seats, refer to Driver and Passenger Vented Seats Malfunction. |
| ⇒ | If both, the seat cushion and seat back blower motors are inoperative or always ON for the driver seat, refer to Vented Seat Malfunction. |
| ⇒ | If both, the seat cushion and seat back blower motors are inoperative or always ON for the passenger seat, refer to Vented Seat Malfunction. |
| ⇒ | If just one of the seat blower motors is inoperative for either seat, refer to Vented Seat Blower Motor Inoperative. |
Circuit/System Testing
Driver and Front Passenger Vented Seats Malfunction
- Ignition OFF, disconnect the X2 harness connector at the CCSM.
- Ignition OFF, test for less than 5 ohms between the ground circuit terminal 6 and ground.
- Ignition ON, verify that a test lamp illuminates between the ignition circuit terminal 3 and ground.
- Ignition OFF, test for less than 15K ohms between the signal circuit terminal 10 and the low reference circuit terminal 5.
- Ignition OFF, disconnect the X1 harness connector at the CCSM.
- Verify that a test lamp illuminates between the B+ circuit terminal B and ground.
- If all circuits test normal, replace the CCSM.
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
| ⇒ | If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance. |
| ⇒ | If greater than the specified range, test the low reference circuit for an open/high resistance. |
| ⇒ | If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. |
Vented Seat Malfunction
- Ignition OFF, disconnect the X2 harness connector at the CCSM.
- Connect a test lamp between the appropriate signal circuit listed below and B+.
- Ignition ON, press the appropriate vented seat switch through the high, medium, and low positions to OFF. The test lamp should dimly illuminate until the OFF position is reached.
- Ignition OFF, test for 1000-15K ohms between the appropriate signal circuit and low reference circuit listed below:
- Ignition OFF, connect the X2 harness connector at the CCSM.
- Disconnect the harness connector at either the seat cushion or seat back blower motor.
- Test for less than 5 ohms between the ground circuit terminal B and ground.
- Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal C and ground.
- Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal A and ground.
- Test for 9.0-12.5 volts between the control circuit terminal A and ground.
- Test for less than 1.0 volt between the control circuit terminal A and ground with the cooled seat switch in the high cool position.
| • | Driver heated/cooled mode PWM serial data terminal 8 |
| • | Passenger heated/cooled mode PWM serial data terminal 7 |
| ⇒ | If the test lamp does not illuminate, test the serial data 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 serial data circuit for a short to ground. If the circuit tests normal, replace the MSM. |
| • | Driver heated/vented seat temperature sensor terminal 10 and terminal 5 |
| • | Passenger heated/vented seat temperature sensor terminal 11 and terminal 5 |
| ⇒ | If greater than the specified range, test the appropriate signal and low reference circuits for a short to voltage or an open/high resistance. If the circuits test normal, test or replace the appropriate seat cushion temperature sensor. |
| ⇒ | 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 appropriate temperature sensor. |
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
| ⇒ | If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. |
| ⇒ | If the test lamp illuminates, test the control circuit for a short to voltage. If the circuit tests normal, replace the CCSM. |
| ⇒ | 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, replace the CCSM. |
Vented Seat Blower Motor Inoperative
- Ignition OFF, disconnect the harness connector at the appropriate seat cushion or seat back blower motor.
- Test for less than 5 ohms between the ground circuit terminal B and ground.
- Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal C and ground.
- Test for 9.0-12.5 volts between the control circuit terminal A and ground .
- If all circuits test normal, test or replace the appropriate blower motor.
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
| ⇒ | If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. |
| ⇒ | If less than the specified range, test the control circuit for an open/high resistance. If the circuit tests normal, replace the CCSM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for CCSM and HVAC control module replacement, setup, and programming |
