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
Battery voltage is supplied at all times to the driver and passenger seat lumbar support switches through 15 A fuses located in the instrument panel fuse block. When a lumbar switch is pressed to inflate the lumbar support, battery voltage is applied through the switch contacts and the inflate control circuit to the seat lumbar adjuster valve assembly. In response to this signal, the lumbar adjuster valve assembly energizes its internal inflate solenoid and applies battery voltage through the seat lumbar support pump control circuit to the pump. The pump runs to inflate the appropriate lumbar bladder until the switch is released. When the switch is pressed to deflate the lumbar support, battery voltage is applied through the switch contacts and the deflate signal circuit to the lumbar adjuster valve assembly. The lumbar adjuster valve assembly energizes its internal deflate solenoid and air is released from the bladder until the switch is released.
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 End Views By Name
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 Verification
1. Ignition ON, press and hold the S65 seat lumbar support switch in the FORWARD direction. The A14 lumbar support pump should run and the upper and lower lumbar support bladders should inflate until the bladders are 100% inflated or the switch is released.
2. Press the S65 lumbar support switch in the REARWARD direction. The upper and lower lumbar support bladders should deflate until the bladders are 100% deflated or the switch is released.
3. Press the S65 lumbar support switch in the UP direction. The A14 lumbar support pump should run and the upper lumbar support bladder should inflate until the bladder is 100% inflated or switch is released.
4. Press and hold the S65 lumbar support switch in the DOWN direction. The upper lumbar bladder should start to deflate while the lower lumbar bladder inflates until the upper lumbar is 100% deflated and the lower lumbar is 100% inflated or the switch is released.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the appropriate S65 seat lumbar support switch.
2. 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.
3. Ignition OFF, connect the harness connector at the S65 seat lumbar support switch and disconnect the harness connector at the Q51 seat lumbar adjuster valve assembly.
4. Test for less than 5 ohms between the ground circuit terminal 5 and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
5. Connect a test lamp between the signal circuit terminals listed below and ground:
* Lumbar up switch signal terminal 1
* Lumbar rearward switch signal terminal 2
* Lumbar down switch signal terminal 3
* Lumbar forward switch signal terminal 4
6. Ignition ON, press and release the S65 seat lumbar support switch in the appropriate direction. The test lamp should turn ON and OFF when changing between the commanded states.
• If the test lamp is always ON, test the signal circuit for a short to voltage. If the circuit tests normal, test or replace the S65 seat lumbar support switch.
• If the test lamp is always OFF, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the S65 seat lumbar support switch.
7. Ignition OFF, connect the harness connector at the Q51 seat lumbar adjuster valve assembly and disconnect the harness connector at the A14 lumbar support pump.
8. Test for less than 5 ohms between the ground circuit terminal 3 and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
9. Connect a test lamp between the control circuit terminal 1 and ground.
10. Ignition ON, command the A14 lumbar support pump ON and OFF by pressing and releasing the lumbar support switch in either the UP or FORWARD direction. The test lamp should turn ON and OFF when changing between the commanded states.
• If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, test or replace the Q51 seat lumbar adjuster valve assembly.
• If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, test or replace the Q51 seat lumbar adjuster valve assembly.
11. If all circuits test normal, test or replace the A14 lumbar support pump.
Component Testing
Lumbar Support Switch
1. Ignition OFF, disconnect the harness connector at the appropriate S65 seat lumbar support switch.
2. Test for infinite resistance between the B+ terminal G and each signal terminal with the switch in the open position.
• If not the specified value, replace the S65 seat lumbar support switch.
3. Test for less than 1 ohms between the B+ terminal G and each signal terminal with the appropriate switch in the closed position.
• If greater than the specified range, replace the S65 seat lumbar support switch.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
Driver or Passenger Seat Lumbar Control Switch Replacement (Driver/Passenger Seat 6-Way Hybrid) Driver or Passenger Seat Lumbar Control Switch Replacement (Driver/Passenger Seat 6-Way Hybrid)