Lumbar Support Inoperative (With Memory A45)
Lumbar Support Inoperative (With Memory A45)
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
Battery voltage is supplied at all times to the memory seat module (MSM) from the 10A LGM/DSM fuse located in the rear fuse block. This voltage is used by the MSM for logic power and to supply battery voltage to the seat and lumbar switches. Battery voltage is supplied at all times to the MSM from the SEATS 30A circuit breaker also located in the rear fuse block. This voltage is used by the MSM to drive the driver seat adjuster motors, recline motor and the lumbar motor.
The lumbar motor is reversible. For example, when the lumbar switch is pressed to move the lumbar support forward, battery positive voltage is applied through the switch contacts and the lumbar forward switch signal circuit to the MSM. In response to this signal, the MSM applies battery voltage through the lumbar motor forward control circuit and ground through the lumbar motor rearward control circuit to the motor. The motor runs to drive the lumbar support forward toward the occupants back until the switch is released. Moving the lumbar support rearward works similarly to moving the lumbar support forward, except that battery positive voltage and ground are applied on the opposite circuits causing the motor to run in the opposite direction.
Diagnostic Aids
The scan tool may reference the Memory Seat Module (MSM) as the Driver Seat Module.
Reference Information
Schematic Reference
Driver Seat Schematics (Driver Seat Schematics)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Lumbar Support Description and Operation (Lumbar Support Description and Operation)
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 (Programming and Relearning)for scan tool information
Circuit/System Verification
1. Ignition ON, verify that all manual power seat functions operate when being controlled by the seat adjuster switches.
• If all power seat functions do not operate, refer to Power Seat Inoperative (With Memory A45) (Power Seat Inoperative (With Memory A45))Power Seat Inoperative (Without Memory A45) (Power Seat Inoperative (Without Memory A45)).
2. Ignition ON, observe the scan tool Driver Seat Module lumbar switch parameter while pressing the lumbar switch. The reading should change between Idle, Forward and Rearward.
• If the reading does not change between the specified values, refer to the Lumbar Switch Circuit Test.
3. If the lumbar switch inputs to the MSM function normal, refer to the Lumbar Motor Control Circuit Test.
Circuit/System Testing
Lumbar Switch Circuit Test
1. Ignition OFF, disconnect the harness connector at the lumbar adjuster switch.
2. 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. If the circuit tests normal, replace the MSM.
3. Verify the scan tool Lumbar Switches parameter is Idle.
• If not the specified value, test the appropriate signal circuit listed below for a short to voltage. If the circuit tests normal, replace the MSM.
* Lumbar horizontal forward terminal C
* Lumbar horizontal rearward terminal B
4. Install a 3A fused jumper wire between the B+ circuit terminal E and the appropriate signal circuit listed below. Verify the scan tool Lumbar Switch parameter is Forward or Rearward.
* Lumbar horizontal forward terminal C
* Lumbar horizontal rearward terminal B
• If not the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the MSM.
5. If all circuits test normal, test or replace the lumbar adjuster switch.
Lumbar Motor Control Circuit Test
1. Ignition OFF, disconnect the harness connector at the lumbar motor.
2. Connect a test lamp between control circuit terminal A and control circuit terminal B.
3. Ignition ON, command the lumbar motor in the Froward/Rearward directions with a scan tool. The test lamp should turn ON when commanding the froward and rearward states.
• If the test lamp remains OFF during either of the commands, test the control circuits for a short to ground or an open/high resistance. If the circuits test normal replace the MSM.
4. If all circuits test normal, test or replace the lumbar motor.
Component Testing
Lumbar Switch
1. Ignition OFF, disconnect the harness connector at the lumbar adjuster switch.
2. Test for infinite resistance between the B+ terminal E and each seat direction signal terminal listed below with the switch in the open position.
* Lumbar horizontal forward switch terminal A
* Lumbar horizontal rearward switch terminal D
• If not the specified value, replace the lumbar switch.
3. Test for infinite resistance between the B+ terminal E and each seat direction signal terminal listed below with the switch in the closed position.
* Lumbar horizontal forward switch terminal A
* Lumbar horizontal rearward switch terminal D
• If greater than the specified range, replace the lumbar switch.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Front Seat Lumbar Control Switch Replacement (Front Seat Lumbar Control Switch Replacement)
* Front Seat Lumbar Support Replacement (Front Seat Lumbar Support Replacement)
* Control Module References (Programming and Relearning)for MSM replacement, setup, and programming