GM Service Manual Online
For 1990-2009 cars only

The power sunroof is controlled by the sunroof switch through the open and close motor control circuits. Ignition voltage is supplied to the sunroof switch through the retained accessory power (RAP) relay and the sunroof 20A fuse in the underhood BEC. While the sunroof switch is in an inactive state both switch contacts are closed to the sunroof switch ground circuit. When an open or close button is pressed on the sunroof switch, its switch contact is closed to the voltage supply circuit. The motor is bi-directional and the direction of motor rotation is determined by which of the motor control circuits is switched to positive voltage while the other remains grounded.