Lumbar Support Inoperative (w/A45)
Lumbar Support Inoperative (w/A45)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) 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 DPM fuse located in the left rear fuse block. This voltage is used by the MSM for logic power and to supply battery reference voltage to the seat and lumbar switches. Battery voltage is supplied at all times to the MSM from the SEATS 30A circuit breaker located in the left rear fuse block. This voltage is used by the MSM to drive the driver seat adjuster motors, recline motor and the lumbar motors.
Both lumbar motors are 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 Position 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 (w/o A45) (Lumbar Support Description and Operation (w/o A45))Lumbar Support Description and Operation (with A45 Disabled) (Lumbar Support Description and Operation (with A45 disabled))Lumbar Support Description and Operation (with A45 Enabled) (Lumbar Support Description and Operation (with A45 enabled))
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
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 seat functions do not operate, refer to Power Seat Inoperative (w/o A45) (Power Seat Inoperative (w/o A45))Power Seat Inoperative (w/A45) (Power Seat Inoperative (w/A45)) .
2. Ignition ON, observe the scan tool Driver Position Module lumbar switch parameters while pressing the appropriate lumbar switch. The reading should change between Inactive and Active.
• If the reading does not change between the specified values, refer to the Lumbar Switch Circuit Test.
3. If all 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 switch.
2. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal G 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. Install a 3A fused jumper wire between the appropriate signal circuit listed below and the B+ circuit terminal G. Verify the scan tool Lumbar Switch parameter is Active.
* Lumbar horizontal forward terminal C
* Lumbar horizontal rearward terminal B
* Lumbar vertical upward terminal F
* Lumbar vertical downward terminal A
• 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.
4. If all circuits test normal, test or replace the lumbar switch.
Lumbar Motor Control Circuit Test
1. Ignition OFF, disconnect the harness connector at the appropriate lumbar motor.
2. Connect a test lamp between the control circuit terminal A and control circuit terminal B.
3. Ignition ON, command the appropriate lumbar motor in the Up/Down or Froward/Rearward directions with a scan tool. The test lamp should turn ON when commanding the up and down or 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 switch.
2. Test for infinite resistance between each seat direction signal terminal listed below and the B+ terminal G with the switch in the open position.
* Lumbar horizontal forward switch terminal C
* Lumbar horizontal rearward switch terminal B
* Lumbar vertical upward switch terminal F
* Lumbar vertical downward switch terminal A
• If not the specified value, replace the lumbar switch.
3. Test for less than 1 ohm between each lumbar direction signal terminal listed below and the B+ terminal G with the switch in the closed position.
* Lumbar horizontal forward switch terminal C
* Lumbar horizontal rearward switch terminal B
* Lumbar vertical upward switch terminal F
* Lumbar vertical downward switch terminal A
• If greater than the specified range, replace the lumbar switch.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Lumbar Switch Replacement (Lumbar Switch Replacement)
* Front Seat Lumbar Support Replacement (Front Seat Lumbar Support Replacement)
* Control Module References (Programming and Relearning) for MSM replacement, setup, and programming