Buick Regal: Power Seat Malfunction (Driver or Passenger without Memory A44 or A45)

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. All power seat motors are inoperative
2. The seat front vertical motor is inoperative
3. The seat horizontal motor is inoperative
4. The seat rear vertical motor is inoperative
5. The seat recline motor is inoperative
6. The seat motor operates until maximum travel is reached

Circuit/System Description

The driver and passenger power seats are completely controlled through the seat adjuster switch. Battery voltage is supplied at all times to the seat adjuster switch through a 30 A fuse located in the underhood fuse block. When the seat switches are in an inactive state, the switch contacts are closed to the switch ground circuit.

All seat motors are reversible. For example, when the seat horizontal forward switch is pressed to move the entire seat forward, battery voltage is applied through the switch contacts and the seat horizontal motor rearward control circuit to the motor. With the horizontal motor rearward switch contacts closed to the switch ground circuit, the motor runs in order to drive the entire seat forward until the switch is released. Moving the entire seat rearward works similarly to moving the entire seat forward, except that battery positive voltage and ground are applied on opposite circuits causing the motor to run in the opposite direction. All seat motors are powered this way.

Reference Information

Schematic Reference

• Driver Seat Wiring Schematics
• Passenger 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 Verification

1. Verify the appropriate driver or passenger seat directional motors listed below operate while operating the seat switches in both directions.

• M51 Seat Horizontal Motor
• M50 Seat Front Vertical Motor
• M55 Seat Rear Vertical Motor
• M56 Seat Recline Motor
• If all seat motors do not operate

Refer to Circuit/System Testing - Seat Adjuster Switch Circuit Test.

• If 1 or more seat motors operate

Refer to Circuit/System Testing - Seat Motor Circuit Test.

• Go to next step: If all seat motors operate

2. All OK.

Circuit/System Testing

Seat Adjuster Switch Circuit Test

1. Ignition OFF, disconnect the harness connector at the appropriate seat adjuster switch listed below:

• S64D Seat Adjuster Switch - Driver
• S64P Seat Adjuster Switch - Passenger

2. Test for less than 10 Ω between the ground circuit terminal B 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 E 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. Test or replace the S64 Seat Adjuster Switch.

Seat Motor Circuit Test

1. Ignition OFF, disconnect the harness connector at the appropriate seat motor listed below:

• M51 Seat Horizontal Motor
• M50 Seat Front Vertical Motor
• M55 Seat Rear Vertical Motor
• M56 Seat Recline Motor

2. Ignition on.

3. Test for less than 1 V between each control circuit and ground.

• If 1 V or greater, repair short to voltage in the control circuit.
• Go to next step: If less than 1 V.

4. Connect a test lamp between control circuit terminal 1 and control circuit terminal 3, ignition ON.

5. Verify the test lamp turns ON when commanding the seat motor Up and Down or Forward and Rearward using the seat adjuster switch.

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

1. Ignition OFF, disconnect the harness connector at the S64 Seat Adjuster 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 S64 Seat Adjuster Switch.

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

6. Test or replace the seat motor.

Component Testing

Seat Adjuster Switch Test

1. Ignition OFF, disconnect the harness connector at the S64 Seat Adjuster Switch.

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

• If less than infinite resistance

Replace the S64 Seat Adjuster Switch.

• Go to next step: If infinite resistance

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

• If 2 Ω or greater

Replace the S64 Seat Adjuster Switch.

• Go to next step: If less than 2 Ω

4. Test for less than 2 Ω between the ground terminal B and each control terminal with the switch in the open position.

• If 2 Ω or greater

Replace the S64 Seat Adjuster Switch.

• Go to next step: If less than 2 Ω

5. All OK.

Seat Motor

1. Ignition OFF, disconnect the harness connector at the appropriate seat motor listed below:

• M51 Seat Horizontal Motor
• M50 Seat Front Vertical Motor
• M55 Seat Rear Vertical Motor
• M56 Seat Recline 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 3 and ground. The seat motor should momentarily perform the appropriate FORWARD/ REARWARD/ UP/ DOWN function.

• If the motor does not perform the FORWARD/ REARWARD/ UP/ DOWN function

Replace the motor.

• Go to next step: If the motor performs the FORWARD/ REARWARD/ UP/ DOWN function

4. Reverse the jumper wires; the motor should perform FORWARD/ REARWARD/ UP/ DOWN function.

• If the motor does not perform the FORWARD/ REARWARD/ UP/ DOWN function

Replace the motor.

• Go to next step: If the motor performs the FORWARD/ REARWARD/ UP/ DOWN function

5. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• Driver or Passenger Seat Adjuster Switch Replacement
• Front Seat Tilt Adjuster Actuator Replacement
• Driver or Passenger Seat Vertical Adjuster Actuator Replacement
• Driver or Passenger Seat Recliner Actuator Replacement (Except GS) or Driver or Passenger Seat Recliner Actuator Replacement (GS)

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