Lumbar Support System Operation
WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2002 GMC Yukon XL, 2002 GMC Yukon, 2002 Chevrolet Tahoe, 2002 Chevrolet Suburban, and 2002 Chevrolet Avalanche. However, it is still accessible from the selected car via links, so may be relevant.
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.