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 seat lumbar support switch through a 15 A fuse located in the underhood 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 support valve assembly. In response to this signal, the lumbar support 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 support valve assembly. The lumbar support 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 Sunshade - Left (DH6)
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.
2. Verify the lumbar support pump turns ON when the lumbar support switch is pressed in the FORWARD direction. The upper and lower lumbar support bladders should inflate until the bladders are 100% inflated or the switch is released.
• If the bladders do not inflate
Refer to Circuit/System Testing
• If the bladders inflate
3. Verify the upper and lower lumbar support bladders deflate when the lumbar REARWARD switch is pressed. The bladders should deflate until the bladders are 100% deflated or the switch is released.
• If the bladders do not deflate
Refer to Circuit/System Testing
• If the bladders deflate
4. Verify the lumbar support pump turns ON and the upper lumbar support bladder starts to inflate when the lumbar switch is pressed in the UP direction. If the lower bladder is inflated it will deflate while the upper bladder inflates until the upper bladder is 100% inflated or switch is released.
• If the pump does not turn ON or the upper bladder does not inflate
Refer to Circuit/System Testing
• If the pump turns ON and the upper bladder inflates
5. Verify the upper lumbar bladder starts to deflate while the lower lumbar bladder starts to inflate while the lumbar switch is pressed in the DOWN direction. The upper bladder should deflate until it is 100% deflated and the lower bladder should inflate until it is 100% inflated or the switch is released.
• If the upper bladder does not deflate or the lower bladder does not inflate
Refer to Circuit/System Testing
• If the upper bladder deflates and the lower bladder inflates
6. All OK.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the appropriate S65 seat lumbar support switch, ignition ON.
2. Verify that a test lamp illuminates between the B+ circuit terminal G and ground.
• If the test lamp does not illuminate and the circuit fuse is good
1. Ignition OFF.
2. Test for less than 2 ohms in the B+ circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, verify the fuse is not open and there is voltage at the fuse.
• If the test lamp does not illuminate and the circuit fuse is open
1. Ignition OFF.
2. Test for infinite resistance between the B+ circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for greater than 10 ohms between each signal circuit listed below and ground:
* Lumbar signal circuit terminal A
* Lumbar signal circuit terminal B
* Lumbar signal circuit terminal C
* Lumbar signal circuit terminal F
• If 10 ohms or less, disconnect the harness connector at the Q51 seat lumbar support valve assembly and retest to verify if the short is in the circuit or the component.
• If greater than 10 ohms, test or replace the S65 seat lumbar support switch.
• If the test lamp illuminates
3. Ignition OFF, connect the harness connector at the S65 seat lumbar support switch and disconnect the harness connector at the Q51 seat lumbar support valve assembly.
4. Test for less than 5 omhs between the ground circuit terminal 5 and ground.
• If 5 omhs or greater
1. Ignition OFF.
2. Test for less than 2 omhs in the ground circuit end to end.
• If 2 omhs or greater, repair the open/high resistance in the circuit.
• If less than 2 omhs, repair the open/high resistance in the ground connection.
• If less than 5 omhs
5. Ignition ON.
6. Verify a test lamp turns ON and OFF between each signal circuit listed below and ground when pressing and releasing the S65 seat lumbar support switch in the appropriate direction.
* Lumbar up switch signal terminal 1
* Lumbar rearward switch signal terminal 2
* Lumbar down switch signal terminal 3
* Lumbar forward switch signal terminal 4
• If the test lamp is always OFF
1. Ignition OFF, disconnect the harness connector at the S65 seat lumbar support switch.
2. Test for infinite resistance between the signal circuit and ground.
• If less than Infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for less than 2 ohms in the signal circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the S65 seat lumbar support switch.
• If the test lamp is always ON
1. Ignition OFF, disconnect the harness connector at the S65 seat lumbar support switch, ignition ON.
2. Test for less than 1 V between the signal circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the S65 seat lumbar support switch.
• If the test lamp turns ON and OFF
7. Ignition OFF, connect the harness connector at the Q51 seat lumbar support valve assembly and disconnect the harness connector at the A14 seat lumbar support pump.
8. Test for less than 5 omhs between the ground circuit terminal 3 and ground.
• If 5 omhs or greater
1. Ignition OFF
2. Test for less than 2 omhs in the ground circuit end to end.
• If 2 omhs or greater, repair the open/high resistance in the circuit.
• If less than 2 omhs, repair the open/high resistance the ground connection.
• If less than 5 omhs
9. Connect a test lamp between the control circuit terminal 1 and ground, ignition ON.
10. Verify the test lamp turns ON and OFF when commanding the A14 seat lumbar support pump ON and OFF by pressing and releasing the lumbar support switch in either the UP or FORWARD direction.
• If the test lamp is always OFF
1. Ignition OFF, disconnect the harness connector at the Q51 seat lumbar support valve assembly.
2. Test for infinite resistance between the control circuit and ground.
• If less than infinite resistance, repair the short to ground on the circuit.
• If infinite resistance
3. Test for less than 2 ohms in the control circuit end to end.
• If 2 ohms or greater, repair the open/high resistance in the circuit.
• If less than 2 ohms, replace the Q51 seat lumbar support valve assembly.
• If the test lamp is always ON
1. Ignition OFF, disconnect the harness connector at the Q51 seat lumbar support valve assembly, ignition ON.
2. Test for less than 1 V between the control circuit and ground.
• If 1 V or greater, repair the short to voltage on the circuit.
• If less than 1 V, replace the Q51 seat lumbar support valve assembly,
• If the test lamp turns ON and OFF
11. Test or replace the A14 seat 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 less than infinite resistance
Replace the S65 seat lumbar support switch.
• If infinite resistance
3. Test for less than 1 omhs between the B+ terminal G and each signal terminal with the appropriate switch in the closed position.
• If 1 ohms or greater
Replace the S65 seat lumbar support switch.
• If less than 1 ohms
4. All OK.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the repair.
* Driver or Passenger Seat Lumbar Control Switch Replacement Driver or Passenger Seat Lumbar Control Switch Replacement
* Driver or Passenger Seat Cushion Air Pump Replacement Service and Repair
* Seat Lumbar Sub System Replacement Seat Lumbar Sub System Replacement