GM Service Manual Online
For 1990-2009 cars only

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.

Circuit/System Description

When the seat switch is operated to lift the seat cushion up, battery positive voltage is applied through the switch contacts and the vertical motor up control circuit to the vertical motor. The motor is grounded through the down switch contacts and the vertical motor down control circuit to the motor. The motor runs in order to drive the seat cushion up until the switch is released. Lowering the seat cushion works similarly to lifting the seat cushion, except that battery positive voltage and ground are applied on opposite circuits causing the motor to run in the opposite direction.

Reference Information

Schematic Reference

Driver Seat Schematics

Connector End View Reference

Power Seat Connector End Views

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

Press the power seat switch up and down. The seat should lift and lower when the switch is pressed.

Circuit/System Testing

  1. Ignition OFF, disconnect the harness connector at the Seat adjuster switch.
  2. Ignition OFF, test for less than 1.0 ohm of resistance between the ground circuit terminal A and ground.
  3. If greater than the specified range, test the ground circuit for an open/high resistance.
  4. Ignition OFF, test for less than 1.0 ohm of resistance between the ground circuit terminal G and ground.
  5. If greater than the specified range, test the ground circuit for an open/high resistance.
  6. Connect a test lamp between the B+ circuit terminal F and ground terminal A. The test lamp should illuminate.
  7. If the test does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
  8. Connect the harness connector at the Seat adjuster switch and disconnect the harness connector at the seat motor. Connect a test lamp between control circuit terminal 1 and control circuit terminal 5.
  9. With the Seat adjuster switch command the seat UP and DOWN. The test lamp should turn ON when commanding the seat UP and DOWN.
  10. If the test lamp remains OFF during either of the commands, test both control circuits for a short to ground or an open/high resistance. If the circuits test normal, test or replace the seat switch.
  11. If all circuits test normal, test or replace the seat motor.

Component Testing

Important:  When performing the following tests, make sure that the device is not all ready in the position the test is attempting to produce.

  1. Ignition OFF, disconnect the harness connector at the seat motor.
  2. Install a 20A fused jumper wire between the control terminal 1 and B+. Momentarily install a jumper wire between the control terminal 5 and ground. The seat motor should rise UP.
  3. If the function does not perform as specified, replace the seat motor.
  4. Reverse the jumper wires, the seat motor should lower down.
  5. If the function does not perform as specified, replace the seat motor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Power Seat Switch Replacement
    •  Seat Adjuster Motor Replacement