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 | High Resistance | Open | Short to Voltage | Signal Performance |
|---|---|---|---|---|---|
B+, MSM Terminal 2 X3 | 2 | 2 | 2 | -- | -- |
B+, MSM Terminal 5 X3 | 1 | 1 | 1 | -- | -- |
B+, Lumbar Massage Switch | 4 | 3 | 3 | -- | -- |
B+, Lumbar Switch | 4 | 1, 2 | 1, 2 | -- | -- |
Driver Seat Lumbar Down Switch Signal | 4 | 2 | 2 | -- | -- |
Driver Seat Lumbar Up Switch Signal | 4 | 2 | 2 | -- | -- |
Driver Seat Lumbar Forward Switch Signal | 4 | 1 | 1 | -- | -- |
Driver Seat Lumbar Rearward Switch Signal | 4 | 1 | 1 | -- | -- |
Lumbar Massage Switch Signal | 4 | 3 | 3 | -- | -- |
Passenger Seat Lumbar Down Switch Signal | 4 | 2 | 2 | -- | -- |
Passenger Seat Lumbar Up Switch Signal | 4 | 2 | 2 | -- | -- |
Driver Seat Lumbar Motor Forward Control | B3920 02 | B1335 0B | 1 | B3920 01 | B1335 42, B1335 4B, B1850 5A |
Driver Seat Lumbar Motor Rearward Control | B3920 02 | B1335 0B | 1 | B3920 01 | B1335 42, B1335 4B, B1850 5A |
Driver Seat Lumbar Motor Down Control | B3921 02 | B1340 0B | 2, 3 | B3921 01 | B1340 42, B1340 4B, B1860 5A |
Driver Seat Lumbar Motor Up Control | B3921 02 | B1340 0B | 2, 3 | B3921 01 | B1340 42, B1340 4B, B1860 5A |
Passenger Seat Lumbar Motor Down Control | B3921 02 | B1340 0B | 2, 3 | B3921 01 | B1340 42, B1340 4B |
Passenger Seat Lumbar Motor Up Control | B3921 02 | B1340 0B | 2, 3 | B3921 01 | B1340 42, B1340 4B |
1. Driver seat lumbar horizontal motor inoperative 2. Driver and front passenger seat lumbar vertical motor inoperative 3. Lumbar massage inoperative 4. Scan Tool Does Not Communicate with Low Speed GMLAN Device | |||||
Circuit/System Description
Battery voltage is supplied to the driver seat and front passenger seat lumbar massage switches from the memory seat module (MSM). When the lumbar massage switch is pressed, battery voltage is applied through the switch contacts and the lumbar massage signal circuit to the MSM. The MSM then cycles battery voltage and ground through the lumbar vertical motor control circuits to the lumbar vertical motor for 10 minutes or until the massage function is canceled. The MSM supplies the lumbar vertical position sensor with a 5-volt reference and low reference circuits. When the motor rotates, the resistance of the potentiometer varies changing the voltage of the lumbar vertical position sensor signal to the MSM.
Diagnostic Aids
The memory seat module is referenced in the Tech 2 as the Driver Position Module.
Reference Information
Connector End View Reference
Description and Operation
Memory Seats Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Ignition ON, verify that all manual seat lumbar functions operate when being controlled by the seat lumbar switches.
- Ignition ON, observe the appropriate scan tool Massage Switch parameter while pressing the appropriate lumbar massage switch. The reading should change between Inactive and Active.
| ⇒ | If all manual seat lumbar functions do not operate, refer to Lumbar Support Inoperative. |
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the appropriate lumbar massage switch.
- Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal C and ground.
- Install a 3A fused jumper wire between the B+ circuit terminal C and the signal circuit terminal A. Verify the Massage Switch parameter is Active.
- If all circuits tests normal, replace the lumbar massage switch.
| ⇒ | If the test lamp does not illuminate, test the B+ circuit for an open/high resistance. |
| ⇒ | If not the specified value, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the MSM. |
Component Testing
Lumbar Massage Switch
- Ignition OFF, disconnect the harness connector at the lumbar massage switch.
- Test for infinite resistance between the signal terminal A and the B+ terminal C with the switch in the open position.
- Test for less than 1 ohm between the signal terminal A and the B+ terminal C with the switch in the closed position.
| ⇒ | If not the specified value, replace the lumbar massage switch. |
| ⇒ | If greater than the specified range, replace the lumbar massage switch. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for MSM replacement, setup, and programming |
