GM Service Manual Online
For 1990-2009 cars only

Power Windows System Components

    • Driver door module (DDM)
    • Passenger door module (PDM)
    • Driver door switch assembly (DDSA)
    • Passenger door power window switch
    • Class 2 serial data link
    • DOOR CONTROLS circuit breaker (30-amp)
    • ACCA/DRIV DR SW fuse (10-amp)

Power Windows Operation

The vehicle is equipped with power windows controlled by door modules. The passenger door window can be operated, either from a power window switch built into the driver door switch assembly (DDSA), or from a power window switch mounted locally on the passenger door. The driver door window can be operated only from the driver door power window switch built into the DDSA.

When the driver door module (DDM) receives a driver door window switch request from the DDSA, the DDM examines the request and checks for messages from other vehicle control modules prohibiting the window movement. If no prohibitive messages have been received, the DDM will apply power and ground to the driver door window motor to move the window as requested.

When the passenger door module (PDM) receives a window switch request from either the DDSA or the window switch mounted locally to it, the PDM will examine the request and check for messages from other vehicle control modules prohibiting the window movement. If no prohibitive messages have been received, the door module will apply power and ground to its associated window motor to move the window as requested.

Window Express Down Feature

Both windows are equipped with the Express Down feature. This feature allows a window to be fully opened by momentarily pressing the window switch to the second detente of the Down position. The passenger window can be expressed down from either the appropriate window switch built into the driver door switch assembly (DDSA) or from the window switch mounted to the passenger door. When either switch is operated to Express Down, both the Down contacts and the Express contacts of the switch being used are closed to ground and the signal is interpreted as an Express Down request. If the window is operated from the passenger door window switch, the passenger door module (PDM) interprets the signal and the window is lowered. If the passenger window is operated from the driver door, the DDSA interprets the signal and communicates via class 2 serial data with the PDM to request the Express Down command to lower the window.

If a door module loses power for any reason such as a vehicle battery disconnect, the power window must be reinitialized once power has been restored. For more detailed information concerning power window reinitialization refer to Power Window Reinitialization .

Normalization

Normalization allows the driver door module (DDM) or passenger door module (PDM) to detect the top position of the window and to calculate actual window position in relation to Zero-Position. The door control module will store this end position once it has been detected when the window has reached the full up position and the user has applied the up function of the switch continuously for a minimum of 0.5 second. Each time the glass stalls short before the Zero-position or stalls short above it, the actual stall position becomes the new Zero-position, if the stall time is at least 0.5 second. It is not possible to normalize the window if the door is open, because the glass stops on the index position. If the door is open and the normalization is lost due to battery disconnect, the actual position of the glass after power is switched ON again will become the Zero-position, and if the door module receives a door open status the glass shall index down.

Window Indexing

The window indexing feature is used to lower the driver and passenger power windows approximately 4 mm when the door is opened. This is necessary to allow the top edge of the window to clear the window weatherstrip. This feature will also raise the window to the fully seated position once the door is closed.

This feature is enabled in the down direction by an input from either the interior or exterior door handle switch. The appropriate door module will then drive the appropriate window motor to lower the window.

This feature is enabled in the up direction by the input from the appropriate door open switch when the door is closed. The appropriate door module will then drive the appropriate window motor to raise the window.