Lumbar Support Inoperative

Lumbar Support Inoperative

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.



Circuit/System Description

Battery voltage is supplied at all times to the driver and passenger seat pumps and the lower and upper lumbar switches. When either of the lumbar switches is operated to inflate or deflate the amount of lumbar support, battery voltage is applied through the switch contacts to the appropriate upper or lower lumbar inflate/deflate control circuit to the seat pump. In response to this signal, the seat pump energizes its internal inflate relay and the pump motor runs to inflate or deflate the appropriate lumbar support bladder in the seat backrest until the switch is released. Ground for the driver seat pump is supplied at ground G301 and the passenger seat pump is at ground G302.


Reference Information
Schematic Reference

* Driver Seat Schematics (Driver Seat Schematics)
* Passenger Seat Schematics (Passenger Seat Schematics)

Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Memory Seats Description and Operation (Memory Seats Description and Operation)
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)


Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the inoperative seat pump.
2. Ignition OFF, test for less than 5.0 ohms of resistance between the seat pump ground circuit terminal A and ground.

• If greater than the specified range, test the ground circuit for an open/high resistance.

3. Verify that a test lamp illuminates between the B+ circuit terminal K and ground.

• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.

4. Ignition OFF, disconnect the harness connector at the inoperative lumbar switch.
5. Verify that a test lamp illuminates between the B+ circuit terminal D and ground.

• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.

6. Connect the harness connector at the inoperative lumbar switch.
7. Connect a test lamp between the appropriate lumbar inflate/deflate control circuit at the seat pump harness connector and ground.
8. Operate the appropriate lumbar switch to the inflate and deflate positions. The test lamp should turn ON and OFF as the switch is cycled between inflate and deflate.

• If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the inoperative lumbar switch.


• If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the inoperative lumbar switch.

9. If all circuits test normal, test or replace the inoperative seat pump.



Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Lumbar Switch Replacement (Lumbar Switch Replacement)
* Lumbar Bladder Replacement (Lumbar Bladder Replacement)
* Lumbar Pump Replacement (Lumbar Pump Replacement)
* Control Module References (Programming and Relearning) for MSM replacement, setup, and programming