Sunroof / Moonroof: Description and Operation

SUNROOF DESCRIPTION AND OPERATION

The power sunroof is controlled by the sunroof control module using inputs from the sunroof switch, retained accessory power (RAP), and hall effect sensors. Ignition voltage is supplied to the sunroof switch and control module through the RAP supply circuit from the body control module (BCM). A high current battery voltage circuit is supplied to the sunroof control module from the 25A sunroof fuse in the underhood based electrical center (BEC) and is used to supply the operating current to the sunroof motor. When a sunroof switch open or close button is pressed the switch contact is closed to the RAP voltage supply circuit. When the sunroof control module detects ignition voltage on a switch signal circuit it determines the switch to be active. The sunroof control module controls the sunroof motor through 2 motor control circuits. While in an inactive state both motor control circuits are closed to the ground contacts within the sunroof control module. To drive the sunroof motor in the open or close direction the sunroof control module will switch the open or close control circuit to the high current battery voltage supply circuit. The motor is bidirectional 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. The sunroof control module continuously monitors sunroof panel operation and calculates its location and direction of travel using 2 hall effect sensors located on the sunroof motor. The hall effect sensors are 2 wire sensors and are supplied with signal and ground circuits from the sunroof control module. The hall effect sensor signal circuits are referenced from battery voltage within the sunroof control module and pulsed low by the hall effect sensors. When the sunroof system has been properly calibrated the sunroof control module will store several sunroof panel locations. Refer to Sunroof Motor/Actuator Synchronization. Opened and closed soft stops are set several millimeters from the physical limits of the sunroof panel to reduce load on the sunroof motor. The vent position is at a preset location between the soft stops as is the flush to close location which is the point where the panel will be driven to the closed soft stop in case the switch is prematurely released.