Lumbar Support Inoperative (Without Memory A45)
Lumbar Support Inoperative (Without Memory A45)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.
Diagnostic Fault Information
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 switches from the LT/PWR/SEAT circuit breaker for the driver seat and the RT/PWR/SEAT circuit breaker for the passenger seat that are located in the I/P fuse block. When the lumbar 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.
Reference Information
Schematic Reference
* Passenger Seat Schematics (Passenger Seat Schematics)
* Driver Seat Schematics (Driver Seat Schematics)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Power Seats System Description and Operation (Power Seats System Description and Operation)
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)
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the lumbar switch.
2. Test for less than 1 ohm 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 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. Ignition OFF, connect the harness connector at the lumbar switch and disconnect the harness connector at the appropriate lumbar motor.
5. Connect a test lamp between control circuit terminal A and control circuit terminal B.
6. Ignition ON, command the appropriate lumbar motor Up and Down or Forward and Rearward using the lumbar switch. The test lamp should turn ON when commanding the up and down or forward and rearward states.
• If the test lamp remains OFF for 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 switch.
7. If all circuits test normal, test or replace the lumbar motor.
Component Testing
Lumbar Switch
1. Ignition OFF, disconnect the harness connector at the lumbar switch.
2. Test for infinite resistance between the B+ terminal G and the switch terminals listed below with the switch in the open position.
* Lumbar horizontal forward switch terminal B
* Lumbar horizontal rearward switch terminal C
* Lumbar vertical upward switch terminal F
* Lumbar vertical downward switch terminal A
• If not the specified value, replace the lumbar switch.
3. Test for less than 1 ohm between the B+ terminal G and the switch terminals listed below with the appropriate switch in the closed position.
* Lumbar horizontal forward switch terminal B
* Lumbar horizontal rearward switch terminal C
* Lumbar vertical upward switch terminal F
* Lumbar vertical downward switch terminal A
• If greater than the specified range, replace the lumbar switch.
4. Test for less than 1 ohm between the ground terminal E and the switch terminals listed below with the switch in the open position.
* Lumbar horizontal forward switch terminal B
* Lumbar horizontal rearward switch terminal C
* Lumbar vertical upward switch terminal F
* Lumbar vertical downward switch terminal A
• If greater than the specified range, replace the lumbar switch.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Lumbar Switch Replacement (Lumbar Switch Replacement)
* Seat Lumbar Sub System Replacement (Seat Lumbar Sub System Replacement)