Sunroof Description and Operation
WARNING: This page does not describe the selected car, but rather 8 other vehicles, including the 2007 GMC Yukon XL, 2007 GMC Yukon, 2007 Chevrolet Tahoe, 2007 Chevrolet Suburban, and 2007 Chevrolet Avalanche. 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 ignition and retained accessory power signal circuits determine when the 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.