The seat lumbar switch is supplied with battery positive voltage from the PWR SEAT circuit breaker located in the I/P fuse block. The seat lumbar switch contains forward and rearward adjustment switches that are normally open to ground. The seat lumbar switch provides both power and ground to the lumbar motor. When the seat lumbar switch is operated to the forward position, battery voltage is applied through the forward switch contacts to the lumbar motor forward control circuit. The lumbar motor rearward control circuit supplies ground through the switch contacts of the rearward switch to G301. The motor will operate to move the lumbar support forward toward the occupant's back until the lumbar is fully extended or the lumbar switch is released. Operating the seat lumbar switch to the rearward position reverses this process. Voltage is applied through the contacts of the rearward switch to the lumbar motor through the lumbar motor rearward control circuit. The lumbar motor forward control circuit supplies ground for the circuit through G301. The motor will operate to move the lumbar support rearward away from the occupant's back until the lumbar is fully retracted or the lumbar switch is released. The lumbar motor contains an internal electronic circuit breaker (PTC) that will open if the motor overheats or binds. The circuit breaker will reset when voltage has been removed from the lumbar motor.

Schematic Reference

Driver Seat Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Lumbar Support Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References

1. Ignition OFF, disconnect the harness connector at the seat lumbar switch.
2. Ignition OFF, verify that a test lamp illuminates between B+ and the ground circuit terminal C.

⇒	If the test lamp does not illuminate, test the ground circuit for an open/high resistance.

3. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal A and ground.

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

4. Reconnect the harness connector at the seat lumbar switch.
5. Ignition OFF, disconnect the harness connector at the seat lumbar motor.
6. Connect a test lamp between control circuit terminal A and ground.
7. Ignition ON, operate the forward lumbar switch ON and OFF. The test lamp should turn ON and OFF as the forward switch is operated.

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

⇒	If the test lamp is always ON, test the control circuit terminal A for a short to voltage. If the circuit tests normal, replace the seat lumbar switch.

8. Connect a test lamp between control circuit terminal B and ground.
9. Ignition ON, operate the rearward lumbar switch ON and OFF. The test lamp should turn ON and OFF as the rearward switch is operated.

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

⇒	If the test lamp is always ON, test the control circuit terminal B for a short to voltage. If the circuit tests normal, replace the seat lumbar switch.

10. If all circuits tests normal, test or replace the seat lumbar motor.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.