Lumbar Support Inoperative (w/o Memory-A45)

Lumbar Support Inoperative (w/o Memory-A45)

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Circuit/System Description

Power seat lumbar support without memory is completely controlled through the seat lumbar adjuster switch. Battery voltage is supplied at all times to the seat lumbar adjuster switch from the PWR SEAT 30A circuit breaker that is located in the right rear fuse block. When the seat adjuster switches are in an inactive state, the switch contacts are closed to the switch ground circuit.

The lumbar horizontal 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.

Circuit/System Testing

1. Disconnect the harness connector at the lumbar adjuster switch.
2. Test for less than 1 ohm of resistance between the ground circuit terminals A and C and ground.

• If greater than 1 ohm, test the ground circuit for an open/high resistance.

3. 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.

4. Connect the harness connector at the lumbar adjuster switch.
5. Disconnect the harness connector at the lumbar motor.
6. Connect a test lamp between the motor control circuits terminal A and terminal B.
7. Press the lumbar switch in the FORWARD and REARWARD directions. The test lamp should turn ON while pressing the switch in the both directions.

• If the test lamp remains OFF for either direction, test the motor circuits for a short to ground or an open/high resistance. If the circuits test normal, test or replace the lumbar adjuster switch.

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

Component Testing

Lumbar Switch
1. Ignition OFF, disconnect the harness connector at the lumbar adjuster switch.
2. Test for infinite resistance between each control terminal (B and E) and the B+ terminal D with the switch in the open position.

• If less than the specified value, replace the lumbar adjuster switch.

3. Test for less than 1 ohm of resistance between each control terminal (B and E) and the B+ terminal D with the switch in the closed position.

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

4. Test for less than 1 ohm of resistance between the control terminal B and the ground terminal C with the switch in the open position.

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

5. Test for less than 1 ohm of resistance between the control terminal E and the ground terminal A with the switch in the open position.

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

Repair Instructions

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

* Lumbar Switch Replacement
* Front Seat Lumbar Support Replacement