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Lumbar Support Malfunction

Lumbar Support Malfunction

Diagnostic Instructions


• Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• Diagnostic Procedure Instructions provides an overview of each diagnostic category.


Diagnostic Fault Information

Circuit Short to Ground Open/High Resistance Short to Voltage Signal Performance
Seat Lumbar Support Switch B+

1

1

-

-

Seat Horizontal Lumbar Deflate Signal

1

2, 3

5

-

Seat Horizontal Lumbar Inflate Signal

1

3

4

-

Seat Vertical Lumbar Deflate Signal

1

2, 3

5

-

Seat Vertical Lumbar Inflate Signal

1

2

4

-

Seat Lumbar Support Pump Control

1

1

4

-

Seat Lumbar Support Pump Ground

-

1

-

-

Seat Lumbar Adjuster Valve Assembly Ground

-

1

-

-

1. The seat lumbar support is inoperative

2. The upper lumbar support is inoperative

3. The lower lumbar support is inoperative

4. The lumbar adjuster pump is always ON

5. The lumbar support will not inflate



Circuit/System Description

Battery voltage is supplied at all times to the driver and passenger seat lumbar support switches 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 signal 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 lumbar support pump control circuit to the pump to inflate the appropriate support 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 seat 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. Ground for the driver and passenger seat lumbar adjuster valve assembly and the lumbar support pump is supplied at G305.

Reference Information

Schematic Reference


• Driver Seat Schematics

• Passenger Seat Schematics


Connector End View Reference

Component Connector End Views

Description and Operation

Lumbar Support Description and Operation

Electrical Information Reference


• Circuit Testing

• Connector Repairs

• Testing for Intermittent Conditions and Poor Connections

• Wiring Repairs


Circuit/System Verification


1. Ignition ON, press and hold the appropriate S65 seat lumbar support switch in the FORWARD direction. The A14 seat lumbar support pump should run and the lower lumbar bladder should start to inflate. After the lower lumbar inflates to approximately 50%, the upper lumbar bladder should start to inflate until both bladders are 100% inflated. The lower lumbar will reach 100% first.

2. Press the S65 seat lumbar support switch in the REARWARD direction. The upper and lower lumbar support bladders should deflate until the switch is released.

3. Press the S65 seat lumbar support switch in the UP direction. The A14 seat lumbar support pump should run and the upper lumbar support bladder should inflate and stay inflated until the deflate switch is pressed.

4. Press and hold the S65 seat 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.


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.

3. 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 S65 seat lumbar support switch and disconnect the harness connector at the Q51 seat lumbar adjuster valve assembly.

5. Test for less than 5 Ω between the ground circuit terminal 5 and ground.

6. If greater than the specified range, test the ground circuit for an open/high resistance.

7. 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

8. 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.

9. 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.

10. 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.

11. Ignition OFF, connect the harness connector at the Q51 seat lumbar adjuster valve assembly and disconnect the harness connector at the A14 seat lumbar support pump.

12. Test for less than 5 Ω between the ground circuit terminal 3 and ground.

13. If greater than the specified range, test the ground circuit for an open/high resistance.

14. Connect a test lamp between the control circuit terminal 1 and ground.

15. Ignition ON, command the A14 seat lumbar support pump ON and OFF by pressing and releasing the S65 seat lumbar support switch in either the UP or FORWARD direction. The test lamp should turn ON and OFF when changing between the commanded states.

16. 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.

17. 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.

18. If all circuits test normal, 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.

3. If not the specified value, replace the S65 seat lumbar support switch.

4. Test for less than 1 Ω between the B+ terminal G and each signal terminal with the appropriate switch in the closed position.

5. If greater than the specified range, replace the S65 seat lumbar support switch.


Repair Instructions

Perform the Diagnostic Repair Verification 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 (8-Way Power)