Lumbar Support Malfunction
Lumbar Support Malfunction
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 is completely controlled through the seat lumbar support switch. Battery voltage is supplied at all times to the lumbar switch through a 20 A fuse located in the underhood fuse block. When the lumbar switches are in an inactive state, the switch contacts are closed to the switch ground circuit.
The lumbar motor is reversible. For example, when the lumbar 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 ([1][2]Electrical Diagrams)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Lumbar Support Description and Operation (Lumbar Support)
Electrical Information Reference
* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the S65D driver seat lumbar support switch.
2. Test for less than 10 Ohms between the ground circuit terminals listed below and ground.
* Terminal A
* Terminal C
• 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 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. Ignition OFF, connect the harness connector at the S65D driver seat lumbar support switch and disconnect the harness connector at the M52D driver seat lumbar support horizontal motor.
5. Connect a test lamp between control circuit terminal A and control circuit terminal B.
6. Ignition ON, command the lumbar motor Forward and Rearward using the lumbar switch. The test lamp should turn ON when commanding the 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 S65D driver seat lumbar support switch.
7. If the circuits test normal replace the M52D driver seat lumbar support horizontal motor.
Component Testing
Lumbar Support Motor
1. Ignition OFF, disconnect the harness connector at the M52D driver seat lumbar support horizontal motor.
Important: When performing the following tests, make sure that the lumbar support is not already in the position the test is attempting to produce.
2. Install a 30 A fused jumper wire between the control terminal A and 12 V. Momentarily install a jumper wire between the control terminal B and ground. The M52D driver seat lumbar support horizontal motor should momentarily perform the FORWARD function.
• If the function does not perform as specified, replace the M52D driver seat lumbar support horizontal motor.
3. Reverse the polarity of jumper wires; the a lumbar motor should perform REARWARD function.
• If the function does not perform as specified, replace the M52D driver seat lumbar support horizontal motor.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Driver Seat Lumbar Control Switch Replacement (Driver Seat Lumbar Control Switch Replacement)
* Driver or Passenger Seat Lumbar Support Actuator Replacement (Driver or Passenger Seat Lumbar Support Actuator Replacement)