Buick Regal: Lumbar/Bolster/Massage Malfunction (AL9 or AT9)

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

1. The power seat and the lumbar support functions are inoperative
2. The lumbar support is inoperative

Circuit/System Description

Battery voltage is supplied at all times to the seat adjuster switch through a 10 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 valve assembly energizes its internal inflate solenoid and runs to inflate the 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 seat lumbar support valve assembly. The 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 Wiring Schematics
• Passenger Seat Wiring Schematics

Connector End View Reference

Component Connector End View Index

Description and Operation

Lumbar Support Description and Operation (With Memory Seat A44/A45) or Lumbar Support Description and Operation (Without Memory Seat A44/A45)

Electrical Information Reference

• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs

Circuit/System Verification

1. Ignition ON.

2. Verify the seat lumbar operates in both directions - Forward/Rearward.

• If either seat lumbar function does not operate

Refer to Circuit/System Testing

• Go to next step: If both seat lumbar functions operate

3. All OK.

Circuit/System Testing

1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the appropriate seat lumbar support switch listed below. It may take up to 2 min for all vehicle systems to power down.

• S65D Seat Lumbar Support Switch - Driver
• S65P Seat Lumbar Support Switch - Passenger

2. Test for less than 10 Ω between the ground circuit terminal E and ground.

• If 10 Ω or greater

1. Ignition OFF.
2. Test for less than 2 Ω in the ground circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than 2 Ω, repair the open/high resistance in the ground connection.

• Go to next step: If less than 10 Ω

3. Ignition ON.

4. Verify a test lamp illuminates between the B+ circuit terminal G and ground.

• If the test lamp does not illuminate

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.
   • Go to next step: If infinite resistance
3. Test for less than 2 Ω in the B+ circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than 2 Ω, verify the circuit fuse is OK and there is voltage at the fuse.

• Go to next step: If the test lamp illuminates

5. 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.

6. Connect a test lamp between control circuit terminal 1 and control circuit terminal 2, ignition ON.

7. Verify the test lamp turns ON when pressing the lumbar switch in the Forward and Rearward directions.

• If the test lamp remains OFF during either of the commands

1. Ignition OFF, remove the test lamp, disconnect the harness connector at the S65 Seat Lumbar Support Switch.
2. Test for infinite resistance between each control circuit and ground.
   • If less than infinite resistance, repair the short to ground on the circuit.
   • Go to next step: If infinite resistance
3. Test for less than 2 Ω in each control circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than 2 Ω, test or replace the S65 Seat Lumbar Support Switch.

• Go to next step: If the test lamp turns ON during each of the commands

8. Test or replace the Q51 Seat Lumbar Support Valve Assembly.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• Driver or Passenger Seat Adjuster Switch Replacement
• Front Seat Back Lumbar Replacement (2 Way) or Front Seat Back Lumbar Replacement (GS) or Front Seat Back Lumbar Replacement (4 Way)

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