Power Windows: Notes

The power window system includes the Body Control Module (BCM), switches in the center console and the power window motors mounted to the window regulator in each door. The BCM controls logic for the driver and passenger door power windows. The BCM receives a muxed hard wired input from each window switch. The programming in the BCM allows it to process the information from this input. The BCM uses the information and hard wired inputs from the door ajar switches to control the courtesy lamps, and to control the operation of the power window after ignition-off feature.

The window lift motors are of the permanent magnet type with a hall effect sensor used for motor movement. The power window system function operates when the ignition switch is in the accessory or On position. However, a unique feature of this system will allow the power windows to be operated for up to 2 minutes after the ignition switch is turned to the Off position, or until a door is opened, whichever occurs first (Accessory Delay). An auto-down feature allows either window to be lowered all the way, even if the window switch is released. Each window has a switch that must be depressed in the down direction to a second detent to begin an auto-down event. Depressing the switch again in any direction will immediately stop the window. When the Windows are being driven in the auto down mode, the BCM knows when to stop because it monitors the hall effect output from the motor. As the motor turns, it has a hall effect sensor that changes state every half revolution (1 mm of window travel/revolution). When the BCM stops receiving hall pulses (no pulses in 100 ms), it stops the window from going down.

Another feature is Smart Glass. The window glass on the Viper is designed to slide up into a seal to prevent the windows from "popping" out at high speeds. To prevent the glass from hanging up on the seal, the BCM drops the glass when the door is opened and returns it when the door is closed. The BCM knows the position of the window by counting the number of pulses as the window motor is turning. When the correct number of pulses have been received, then the window is stopped. After the door is closed, then the BCM will drive the window up into seal until no pulses are received in 100 ms.