Power Windows Description and Operation
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Power Windows Description and Operation
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Power Windows System Components
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The power window system consists of the following components:
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Passenger window switch
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Left rear window switch
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Right rear window switch
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Window motors in each of the doors
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Body Control Module (BCM)
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This vehicle can be configured as driver express up and express down power window motor and passenger, left rear, right rear express down window motors.
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Window lift motor driver and passenger side express up and express down
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The driver door contains a window motor is smart motor that will detect excessive resistance while performing the express up function and automatically reverse direction to prevent injury to any occupants that may become trapped between the closing window and the door frame. The automatic reverse safety feature can be overridden by pulling and holding the window switch.
The logic circuit in the driver's door's window lift motor monitors the signal circuits for up, down and express movements, which normally means a B+ voltage. When a window switch is actuated on the driver's side the contacts make, causing a voltage drop in the current signal circuit. The window motor will detect the voltage drop and will command the window to move in the direction requested.
Driver's window switch communicates to the BCM by a serial data circuit. When the driver wishes to control the passenger side window, the driver will use the appropriate switch on the driver window switch. When this switch is used, a serial data message is sent to the BCM requesting a window motor command, the BCM will then send a serial data message to the appropriate door window switch which will then command that window to move in the direction requested.
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Window lift motors left rear, right rear express down
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For the passenger, right rear and left rear doors, when their window switch is pressed in the down position, battery positive voltage is applied to their respective window motor control circuit and ground to the other window motor control circuit causing that window to open. When the individual window switch is pulled in the up position, voltage and ground is applied to the window motor in the opposite direction causing that window to close. The return path to ground is supplied through the inactive control circuit being normally grounded through the window switch.
The rear window switch communicates to the BCM by a serial data circuit. When the driver wishes to control the left or right rear window, the driver will use the appropriate switch on the driver window switch. When this switch is used, a serial data message is sent to the BCM requesting a window motor command, the BCM will then send a serial data message to the appropriate door window switch which will then command that window to move in the direction requested.
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Express down and comfort opening of all windows
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Some models are equipped with express down function for all windows simultaneously. Function is controlled by BCM. When the remote control's unlock button is pressed and held down, the keyless entry control module sends a serial data message to BCM with a request to open all windows.
The driver power window switch panel contains a power window lockout switch. When the driver presses the window lockout switch, a serial data message is sent to the BCM which in turn deactivates the rear window switches. The rear windows will still function normally from the switches on the driver window switch.
