Lumbar Support Inoperative
Lumbar Support Inoperative
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
Diagnostic Fault Information
Circuit/System Description
The seat lumbar switch is supplied with battery positive voltage from the PWR SEAT circuit breaker located in the I/P fuse block. The seat lumbar switch contains inward and outward adjustment switches that are normally open to ground. The seat lumbar switch provides both power and ground to the lumbar motor. When the seat lumbar switch is operated to the outward position, battery voltage is applied through the outward switch contacts to the lumbar motor outward control circuit. The lumbar motor inward control circuit supplies ground through the switch contacts of the inward switch to G301. The motor will operate to move the lumbar support outward toward the occupant's back until the lumbar is fully extended or the lumbar switch is released. Operating the seat lumbar switch to the inward position reverses this process. Voltage is applied through the contacts of the inward switch to the lumbar motor through the lumbar motor inward control circuit. The lumbar motor outward control circuit supplies ground for the circuit through G301. The motor will operate to move the lumbar support inward away from the occupant's back until the lumbar is fully retracted or the lumbar switch is released. The lumbar motor contains an internal electronic circuit breaker (PTC) that will open if the motor overheats or binds. The circuit breaker will reset when voltage has been removed from the lumbar motor.
Reference Information
Schematic Reference
Driver Seat Schematics (Driver Seat Diagrams)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Lumbar Support Description and Operation (Lumbar Support 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)
Scan Tool Reference
Control Module References (Programming and Relearning)
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the seat lumbar switch.
2. Ignition OFF, verify that a test lamp illuminates between B+ and the ground circuit terminal C.
• If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
3. Ignition OFF, verify that a test lamp illuminates between B+ and the ground circuit terminal H.
• If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
4. Ignition ON, verify that a test lamp illuminates between the B+ circuit terminal E and ground.
• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
5. Reconnect the harness connector at the seat lumbar switch.
6. Ignition OFF, disconnect the harness connector at the seat lumbar motor.
7. Connect a test lamp between control circuit terminal A and ground.
8. Ignition ON, operate the outward lumbar switch ON and OFF. The test lamp should turn ON and OFF as the forward switch is operated.
• If the test lamp is always OFF, test the control circuit terminal A for a short to ground or an open/high resistance. If the circuit tests normal, replace the seat lumbar switch.
• If the test lamp is always ON, test the control circuit terminal A for a short to voltage. If the circuit tests normal, replace the seat lumbar switch.
9. Connect a test lamp between control circuit terminal B and ground.
10. Ignition ON, operate the inward lumbar switch ON and OFF. The test lamp should turn ON and OFF as the rearward switch is operated.
• If the test lamp is always OFF, test the control circuit terminal B for a short to ground or an open/high resistance. If the circuit tests normal, replace the seat lumbar switch.
• If the test lamp is always ON, test the control circuit terminal B for a short to voltage. If the circuit tests normal, replace the seat lumbar switch.
11. If all circuits tests normal, test or replace the seat lumbar motor.
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)