Buick Regal: Power Folding Seat 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

1. The left rear power folding seat is inoperative.
2. The right rear power folding seat is inoperative.

Circuit/System Description

Battery voltage is supplied at all times to the folding seat control switch through a 15 A fuse located in the instrument panel fuse block. When the folding seat control switch is pressed to fold the seat back cushion forward, battery voltage is applied through the switch contacts and the folding seat motor control circuit to the motor. The motor runs in order to fold the seat back cushion forward.

Reference Information

Schematic Reference

Rear Seat Wiring Schematics

Connector End View Reference

Component Connector End View Index

Description and Operation

Power Seats System Description and Operation

Electrical Information Reference

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

Circuit/System Testing

1. Ignition OFF and all vehicle systems OFF, disconnect the harness connector at the appropriate folding seat motor listed below:

• M19LR Folding Seat Motor - Left Rear
• M19RR Folding Seat Motor - Right Rear

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

• If 10 Ω or greater

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

4. Verify the test lamp does not turn ON when commanding the M19 Folding Seat Motor froward using the S20 Folding Seat Control Switch.

• If the test lamp turns ON during each of the commands

5. Test or replace the M19 Folding Seat Motor.

• Go to next step: If the test lamp does not turn ON during either of the commands

6. Ignition OFF, disconnect the harness connector at the appropriate folding seat control switch listed below:

• S20LR Folding Seat Control Switch - Left Rear
• S20RR Folding Seat Control Switch - Right Rear

7. Ignition ON.

8. Verify a test lamp illuminates between the B+ circuit terminal 5 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 fuse is not open and there is voltage at the fuse.

• Go to next step: If the test lamp illuminates

9. Test for infinite resistance between the control circuit and ground.

• If less than infinite resistance, repair the short to ground on the circuit.
• Go to next step: If infinite resistance

10. Test for less than 2 Ω in the control circuit end to end.

• If 2 Ω or greater, repair the open/high resistance in the circuit.
• Go to next step: If less than 2 Ω

11. Test or replace the S20 Folding Seat Control Switch.

Component Testing

Folding Seat Control Switch

1. Ignition OFF, disconnect the harness connector at the S20 Folding Seat Control Switch.

2. Test for infinite resistance between the B+ terminal 5 and the control terminal 1 with the switch in the open position.

• If less than infinite resistance

Replace the S20 Folding Seat Control Switch.

3. Test for less than 2 Ω between the B+ terminal 5 and each control terminal 1 with the switch in the closed position.

• If 2 Ω or greater

Replace the S20 Folding Seat Control Switch.

• Go to next step: If less than 2 Ω

4. All OK.

Folding Seat Motor

1. Ignition OFF, disconnect the harness connector at the M19 Folding Seat Motor.

NOTE: When performing the following tests, make sure that the seat is not already in the position the test is attempting to produce.

2. Install a 30 A fused jumper wire between control terminal 1 and 12 V.

3. Momentarily install a jumper wire between control terminal 2 and ground. The seat motor should momentarily perform the FORWARD function.

• If the motor does not perform the FORWARD function

Replace the motor.

• Go to next step: If the motor performs the FORWARD function

4. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• Rear Seat Back Folding Switch Replacement
• Rear Seat Recliner Actuator Replacement

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