Lumbar Support Inoperative (Without Memory - A45)
Lumbar Support Inoperative (Without Memory - A45)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) 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 30 amp 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.
Reference Information
Schematic Reference
* Driver Seat Schematics (Driver Seat Schematics)
* Passenger Seat Schematics (Passenger Seat Schematics)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Power Seats System Description and Operation (Folding Seat) (Power Seats System Description and Operation (Folding Seat))Power Seats System Description and Operation (Front Seat) (Power Seats System Description and Operation (Front Seat))
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
Scan Tool Reference
Control Module References (Programming and Relearning)
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the lumbar adjuster switch.
2. Ignition OFF, test for less than 1 ohm of resistance 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 1 ohm of resistance 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. Connect the harness connector at the lumbar adjuster switch.
6. Disconnect the harness connector at the lumbar motor.
7. Connect a test lamp between the motor control circuits terminal A and terminal B.
8. Ignition ON, operate the lumbar switch to the FORWARD and REARWARD positions. The test lamp should turn ON while operating the switch in both directions.
• If the test lamp remains OFF for either direction, test the motor control circuits for a short to ground or an open/high resistance. If the circuits test normal, test or replace the lumbar adjuster switch.
9. If all circuits test normal, 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 B+ terminal D and each control terminal (B and E) 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 the B+ terminal D and each control terminal (B and E) 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 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 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 (Verification Tests) after completing the diagnostic procedure.
* Lumbar Switch Replacement (Lumbar Switch Replacement)
* Front Seat Lumbar Support Replacement (Front Seat Lumbar Support Replacement)