Lumbar Support Inoperative (W/O Memory)

LUMBAR SUPPORT INOPERATIVE (W/O MEMORY-A45)

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 MSM/RT FRT PWR SEAT 25A circuit breaker that is located in the rear fuse block. When the seat adjuster switches are in an inactive state, the switch contacts are closed to the switch ground circuit.

Both lumbar motors are 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. The lumbar support vertical motor is also powered this way.

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 terminal E and ground.
- If greater than 1 ohm, test the ground circuit for an open/high resistance.
3. Verify that a test lamp illuminates between the B+ circuit terminal G 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 assembly.
6. Connect a test lamp across the motor control circuit terminals for the inoperative motor.
7. Verify that the test lamp illuminates while pressing the lumbar switch in both directions.
- If the test lamp does not illuminate for both directions, test the motor circuits for a short to ground or an open/high resistance. If the circuits test normal replace the lumbar adjuster switch.
8. If the circuits test normal replace the lumbar motor assembly.

REPAIR INSTRUCTIONS
Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests
- Lumbar Switch Replacement - Front
- Lumbar Replacement - Front Seat (w/AL2) Lumbar Replacement - Front Seat (w/AM3)