Sunroof Description and Operation
WARNING: This page is about a different car, the 2008 GMC Sierra, 2008 GMC Cab & Chassis Sierra, 2008 Chevrolet Silverado, and 2008 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.
The power sunroof is operated by the sunroof motor/actuator which consists of the motor and electronic control unit as a complete assembly. The system is powered by a battery supply circuit and an ignition/retained accessory power signal circuit determines when the sunroof may be operated. The switch signal circuits are supplied battery voltage through a resistor and monitored within the ECU. When a sunroof switch is pressed the switch signal circuit is closed to ground and most of the voltage supplied to the signal circuit will be dropped across the resistor within the ECU indicating the switch is active.