GM Service Manual Online
For 1990-2009 cars only

Three reversible motors operate the power seats. The front and back heights of the seat are controlled by different motors. The motors may be raised or lowered independently of each other by pushing the front or the rear of the power seat switch. When the entire power seat switch is pushed to the UP or the DOWN position, both motors run in order to move the front and back of the seat up or down at the same time.

The power seat switch operates the forward-back motor. When the power seat switch is held in the FORWARD position, battery voltage is applied through the switch contacts to CKT 285 and the forward-back motor. The motor is grounded through CKT 284 and the contacts of the power seat switch. The motor runs in order to drive the seat forward until the switch is released.

When the power seat switch is in the BACK position, CKT 284 receives battery voltage and CKT 285 is grounded. This reverse polarity causes the motor to run in the opposite direction. This action drives the seat backwards.

The front and rear height motors operate in a similar way when the front or the rear of the power seat switch is operated.

When the power seat switch is held in the UP position, the entire seat is raised. Battery voltage is applied to the following circuits:

    • CKT 282
    • CKT 286

Ground is applied to the following circuits:

    • CKT 283
    • CKT 287

Both motors run in order to drive the entire seat upward. A similar action occurs in order to move the entire seat downward.

Each motor is protected by a built-in electronic circuit breaker (PTC). The PTC resistance increases under the following conditions:

    • The power seat switch is held too long with the seat obstructed.
    • The seat is fully up.
    • The seat is fully down.
    • The seat is fully forward.
    • The seat is fully back.

The resistance returns to normal after the voltage is removed from the motor terminals.