Lumbar Support Inoperative

Lumbar Support Inoperative

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

B+ is supplied to the lumbar adjuster switch from the PWR SEAT circuit breaker. Ground is supplied to the lumbar adjuster switch from G301. When the lumbar adjuster switch is pressed to increase or decrease lumbar support, the lumbar adjuster switch provides voltage and ground to the appropriate terminals of the seat lumbar motor.

Reference Information
Schematic Reference

Driver Seat Schematics ([1][2]Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Lumbar Support Description and Operation (Lumbar Support)
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)

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the lumbar adjuster switch.
2. Test for less than 5 ohms between the ground circuit terminal A and ground.

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

3. Test for less than 5 ohms between the ground circuit terminal C and ground.

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

4. Ignition ON, 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.

5. Ignition OFF, connect the harness connector at lumbar adjuster switch and disconnect the harness connector at the lumbar motor.
6. Connect a test lamp between control circuit terminal 1 and control circuit terminal 2.
7. Verify the test lamp illuminates while pressing the lumbar adjuster switch in both directions.

• If the test lamp does not illuminate for both directions, test the control circuits for a short to ground or an open/high resistance. If the circuits test normal, test or replace the lumbar switch.

8. If all circuits test normal, test or replace the lumbar motor.

Component Testing

Lumbar Adjuster Switch
1. Ignition OFF, disconnect the harness connector at the lumbar adjuster switch.
2. Test for infinite resistance between the control terminals listed below and the B+ terminal D with the switch in the open position.

* Lumbar horizontal forward terminal E
* Lumbar horizontal rearward terminal B

• If not the specified value, replace the lumbar adjuster switch.

3. Test for less than 2 ohms between the control terminals listed below and the B+ terminal D with the switch in the closed position.

* Lumbar horizontal forward terminal E
* Lumbar horizontal rearward terminal B

• If greater than the specified range, replace the lumbar adjuster switch.

4. Test for less than 2 ohms between control terminal B and the ground terminal A with the switch in the open position.

• If greater than the specified range, replace the lumbar adjuster switch.

5. Test for less than 2 ohms between control terminal E and the ground terminal C with the switch in the open position.

• If greater than the specified range, replace the lumbar adjuster switch.

Lumbar Motor
1. Ignition OFF, disconnect the harness connector at the lumbar motor.

Important: When performing the following tests, make sure that the lumbar is not already in the position the test is attempting to produce.


2. Install a 30A fused jumper wire between the control terminal 1 and 12 volts. Momentarily install a jumper wire between the control terminal 2 and ground. The lumbar motor should momentarily perform the FORWARD function.

• If the function does not perform as specified, replace the lumbar motor.

3. Reverse the polarity of jumper wires; the a lumbar motor should perform the REARWARD function.

• If the function does not perform as specified, replace the lumbar motor.

Repair Instructions

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

* Lumbar Switch Replacement (Lumbar Switch Replacement)
* Driver or Passenger Seat Lumbar Support Replacement (Driver or Passenger Seat Lumbar Support Replacement)