GM Service Manual Online
For 1990-2009 cars only

Power Sunroof System Components

The power sunroof system consists of the following components:

    • Sunroof control module
    • Sunroof switch
    • Sunroof glass, tilt/slide type, with glass sliding between roof and headliner
    • Rail and track assembly upon which the sunroof glass rides
    • Sunshade
    • SUNROOF Fuse 20 A
    • Body control module (BCM)
    • Ground G401

Power and Grounds

Battery positive voltage is supplied at all times to the sunroof control module from the 20 A SUNROOF fuse located in the underhood fuse block. Ground is supplied to the sunroof control module through the ground circuit and G401.

Ground is supplied to the sunroof switch through the switch ground circuit and the sunroof control module.

Power Sunroof Operation

The power sunroof will operate with the ignition switch turned to Accessory or RUN, this allows for retained accessory power (RAP) control of the sunroof through the BCM. With the ignition in the run or accessory position, the BCM pulls the sunroof enable circuit of the sunroof control module high allowing sunroof operation. Once the ignition switch is turned to OFF the sunroof will continue to operate until any door is opened or when the RAP timer reaches its shut-off limit. For a description and operation of the RAP operation, refer to Retained Accessory Power (RAP) Description and Operation.

Sunroof Switch

The sunroof switch is a multifunction type switch, located in the front center of the healiner. It contains two rocker type switches that are used to control the following sunroof functions:

    • Roof open/close
    • Roof express open
    • Vent open/close

Express Open

The express open will only operate with the sunroof in the fully closed or partially open position. To express open the sunroof glass, momentarily press the sunroof switch to the second rearward position once. This will apply the sunroof switch low reference circuit to both the sunroof switch express signal circuit and to the sunroof switch open signal circuit (12 V references) inputs, pulling them to 0 V momentarily. The momentary transition inputs to the sunroof control module indicates an express open request. Once the express open has been initiated, the sunroof control module will drive the motor in the open direction, slightly lowering the rear edge of the sunroof glass, then sliding open with the sunshade. The sunroof glass will continue to express open until:

    • The sunroof glass reaches the comfort stop position.
    • Activation of the sunroof switch (in any direction) to stop the sunroof glass in a desired position other than the express open position.
    • The operation time-out expires, 15 seconds after the initiation of the express open feature has been requested.

To Open

Opening the sunroof can be done from any position between fully closed and partially open. To open the sunroof glass, press and hold the sunroof switch to the first rearward position. This will apply the sunroof switch low reference circuit to the sunroof switch open signal circuit (12 V reference) input, pulling the reference voltage to 0 V. The constant low (0 V) input to the sunroof control module indicates an open request. Once the open request has been initiated, the sunroof control module will drive the motor in the open direction, slightly lowering the rear edge of the sunroof glass, then sliding open with the sunshade. The sunroof glass will continue to open until the sunroof motion is terminated by either:

    • Motor stall is sensed because the sunroof has reached its limit of travel.
    • Releasing of the sunroof switch. The sunroof may be left in any position between fully open and fully closed.

To Vent Open

Opening the sunroof glass, to the vent position, can be done when it is between fully closed and partially vent. Pull down on the front of the switch. This will apply the sunroof switch low reference circuit to the sunroof switch open vent signal circuit. Holding the sunroof switch in the vent position will cause the sunroof switch open vent signal circuit (12 V reference) input to be pulled to 0 V. The constant low input to the sunroof control module indicates an open vent request. Once the open vent request has been initiated, the sunroof control module will drive the motor in the closed direction (to vent position) until the sunroof motion is terminated by either:

    • Motor stall is sensed because the sunroof has reached its limit of travel.
    • Releasing of the sunroof switch.

Closing to the Fully Closed Position

To close the power sunroof from the following positions:

    • Open position, push and hold the sunroof switch forward.
    • Vent position, pull and hold downward the sunroof switch.

Holding the sunroof switch to the close position will cause the sunroof switch close signal and sunroof switch close vent signal circuits (12 V references) to be pulled to 0 V. The constant low inputs to the sunroof control module indicates a close request. As the close request has been initiated, the sunroof control module will drive the motor to the closed position until the limit switch closes, indicating a flush close position. As the sunroof glass nears the closed position, the wind deflector will retract, and the rear sunroof glass will raise slightly, then seats to flush with the roof panel. To close the sunshade, this will have to be manually slid closed.

Sunroof Motor

The sunroof motor/actuator assembly has a bi-directional motor. The sunroof motor understands when it has driven the sunroof glass to the vent, close, and full open positions based on the internal hall effect sensors within the motor/actuator assembly. It interprets the hall effect sensor combinations and controls the sunroof motor to comfort stop the sunroof glass at the open closed position.