GM Service Manual Online
For 1990-2009 cars only

Power Window System Components

The power window system consists of the following components:

    • Left front power window master switch
    • Right front power window switch
    • Left rear power window switch (4-door vehicles)
    • Right rear power window switch (4-door vehicles)
    • Window lockout switch (4-door vehicles)
    • Auto Down Module
    • Reversible power window motors in each of the doors (circuit breaker protected)
    • PWR WDO CB 30A

Power Window System Controls

The power window system will operate anytime the Retained Accessory Power (RAP) system is active or when the ignition switch is in the ACCY or ON position.

The LF power window master switch can control the up and down functions of all the windows in the vehicle. The passenger door power window switches can only control the up and down functions of the individual window. The power window master switch also contains a lockout switch (4-door vehicles). The lockout switch controls the power window master switch lockout signal circuit. When the lockout switch is in the OFF position, the power window master switch lockout signal circuit is complete and the passenger door power window switches function normally. When the lockout switch is in the ON position, the power window master switch lockout signal circuit is interrupted and the passenger door window switches cannot control the up and down functions of the power windows.

Power Window Motor Operation

A permanent magnet motor operates each of the power side windows. Each motor raises or lowers the glass when the motor receives voltage. The direction the motor turns depends on the polarity of the supply voltage. The power window switches control the polarity of the supply voltage. A built-in circuit breaker protects each motor. The circuit breaker opens when the switch is depressed for a extended period of time under the following conditions:

    • The window has an obstruction.
    • The window is fully open or fully closed.

The circuit breaker will reset automatically as the circuit breaker cools.

Power Window Operation

The normally closed contacts of the power window switch are connected to ground and the center pole is connected to the accessory voltage circuit. By placing the either power window switch in the down position, voltage is applied to the power window motor down circuit and to the power window motor. The other side of the power window motor is connected to ground through the normally closed contacts of the power window switch through the power window motor up circuit and drives the window down.

By placing the power window switch in the up position the polarity of the motor is reversed and the motor drives the window up.

Express Down Operation

Vehicles equipped with the express down function incorporate an auto down module in the power window master switch. The auto down module senses the operation of the LF window switch and controls voltage and ground availability to the power window up and down circuits.

When the LF power window switch is held in the down position for more then 1 second, the auto down module supplies voltage to the power window down circuit continuously until the power window reaches the bottom of its travel. At this point, the auto down module senses an over current situation on the power window down circuit and interrupts the voltage supply. If the LF power window switch is actuated less then 1 second, the operation is the same except the power window down circuit will be interrupted when the switch is released.