GM Service Manual Online
For 1990-2009 cars only

Power Seats System Components

The driver and front passenger power seat systems each consist of the following components:

    • Seat adjuster switch
    • Seat horizontal motor
    • Seat front vertical motor
    • Seat rear vertical motor
    • PWR SEAT circuit breaker 25 amp

Power Seat Adjuster Switch

The driver and front passenger seat adjuster switches are supplied battery positive voltage at all times from the PWR SEAT circuit breaker located in the I/P fuse block. The seat adjuster switches provide both power and ground to the selected seat adjuster motors. The seat adjuster switches are grounded through the switch ground circuit at G 301.

Power Seat Adjuster Motors

The seat adjuster motor assembly consists of three motors. They are the horizontal motor, front vertical motor, and rear vertical motor. Each seat adjuster motor operates independently. The horizontal motor moves the entire seat forward and rearward. Both vertical motors run simultaneously when the seat switch is operated to move the entire seat up and down. Or they can be selected independently to vertically tilt the front or rear of the seat up and down. Each motor contains an internal electronic circuit breaker (PTC) that will open if the motor overheats or binds. The circuit breaker will reset when voltage has been removed from the lumbar motor.

Horizontal Adjuster Motor

When the seat switch is operated to move the entire seat forward, battery positive voltage is applied through the horizontal motor forward switch contacts and the horizontal motor forward control circuit to the motor. The motor is grounded through the horizontal motor rearward switch contacts and the horizontal motor rearward control circuit to the motor. 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.

Rear Vertical Adjuster Motor

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

Front Vertical Adjuster Motor

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

Entire Seat Up or Down

When the seat switch is operated in order to move the entire seat to the up position, battery positive voltage is simultaneously applied through the front and rear vertical motor up switch contacts and the front and rear vertical motor up control circuits to both vertical motors. The motors are grounded through the front and rear vertical motor down switch contacts and the front and rear vertical motor down control circuits to both vertical motors. Both motors run simultaneously in order to drive the entire seat up until the switch is released. Moving the entire seat down works similarly to moving the entire seat up, except that battery positive voltage and ground are applied on the opposite circuits causing the motors to run in the opposite direction.