GM Service Manual Online
For 1990-2009 cars only

Lumbar Support System Components

The lumbar support system for the driver and passenger seat consists of the following components:

    • Lumbar/bolster switch
    • Seat lumbar motor
    • Seat bolster motor
    • SEAT 25A circuit breaker

Lumbar Support System Operation

The lumbar support and bolster motors are operated by a four position switch in each seat. Battery voltage is supplied to the lumbar/bolster switch from the SEAT 25A circuit breaker. While the lumbar/bolster switches are in an inactive state the switch contacts are closed to the lumbar/bolster switch ground circuit. When a lumbar/bolster switch is pressed to an active state the switch contact is closed to the battery voltage supply circuit. Each lumbar/bolster motor is controlled by the lumbar/bolster switch through 2 motor control circuits. The lumbar/bolster motors are bidirectional and the direction of motor rotation is determined by which of the motor control circuits is switched to battery voltage while the other remains grounded.