Power seat lumbar support without memory is completely controlled through the lumbar switch. Battery voltage is supplied at all times to the lumbar switch through the PWR SEATS 40A fuse in the underhood fuse block and the 25 A Seat circuit breaker located in the in the driver seat wiring harness. When the lumbar switches are in an inactive state, the switch contacts are closed to the switch ground circuit at G345.

The lumbar motor is reversible. For example, when the lumbar horizontal forward switch is pressed to move the lumbar support forward, battery voltage is applied through the switch contacts and the lumbar motor forward control circuit to the motor. The motor is grounded through the lumbar motor rearward switch contacts and the lumbar motor rearward control circuit to the motor. The motor runs in order 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 opposite circuits causing the motor to run in the opposite direction.

Schematic Reference

Connector End View Reference

Component Connector End Views

Description and Operation

Lumbar Support Description and Operation

Electrical Information Reference

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

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

3. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal H 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, connect the harness connector at the lumbar switch and disconnect the harness connector at the lumbar motor.
5. Connect a test lamp between control circuit terminal A and control circuit terminal B.
6. Operate the lumbar switch in both directions. The test lamp should turn ON when commanding the lumbar motor in both directions.

⇒	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, test or replace the lumbar adjuster switch.

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

Seat Adjuster Switch

1. Ignition OFF, disconnect the harness connector at the appropriate seat lumbar adjuster switch.
2. Test for infinite resistance between the B+ terminal H and each control terminal listed below with the switch in the open position:

•	Lumbar forward terminal F

•	Lumbar rearward terminal G

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

3. Test for less than 1 ohm between the B+ terminal H and each control terminal listed below with the switch in the closed position:

•	Lumbar forward terminal F

•	Lumbar rearward terminal G

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

4. Test for less than 1 ohm between the ground terminal E and control terminals listed below with the switch in the open position:

•	Lumbar forward terminal F

•	Lumbar rearward terminal G

⇒	If greater than the specified range, replace the seat adjuster switch.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.