GM Service Manual Online
For 1990-2009 cars only

A permanent magnet motor operates each power window. Each motor raises or lowers the glass when voltage is supplied. The direction the motor turns depends on the polarity of the supply voltage.

The LH front power window switch controls the following components:

    • All of the motors
    • Power window control module

Each window switch controls only 1 motor.

LH Front Power Window Switch Operation

Battery voltage is applied to the POWER WDO/SUNROOF RELAY coil in the IP junction block from CKT 43 under the following conditions:

    • The ignition switch is in the ACCY position.
    • The ignition switch is in the RUN position.
    • During the retaining accessory power (RAP).

The relay is permanently grounded on the coil side. Battery voltage is applied to the LH front power window switch under the following conditions:

    • The coil is energized.
    • The switch is closed.

Battery voltage is applied to the window motor when any UP switch in the LH front power window switch not associated with the express down is operated. The window motor is grounded through the DOWN contact of the LH front power window switch. The motor runs in order to drive the window up. Battery voltage is applied to the window motor in the opposite direction when any DOWN switch in the LH front power window switch is operated. The window motor is grounded through the UP contact in the LH front power window switch. The motor runs in order to drive the window down.

EXPRESS DOWN Window Operation

The EXPRESS DOWN window function is a convenience feature that allows you to fully open the left front window by holding the left front power window switch down for more than 0.3 seconds then releasing. You may stop the window at any position by momentarily pressing the UP or DOWN switch.

The power window control module receives the power at terminal A under the following conditions:

    • The ignition switch is in the ACCY position.
    • The ignition switch is in the RUN position.
    • During the retaining accessory power (RAP).

When the left front window switch is held down for more than 0.3 seconds and released, the timer and control unit detects this at the down input terminal. The relay control switch closes, completing the coil circuit through the UP switch in the left front power window switch to ground. The relay contacts close. The LH front power window motor receives battery voltage. Terminal A of the motor is grounded through the left front power window switch UP contact. When the window is fully down, the motor stall current is detected at the current sense input of the timer and control unit. The relay control switch opens, de-energizing the coil and disconnecting the power to the motor. The motor also stops 10-30 seconds after the DOWN switch is pushed.

The timer and control unit detects at the input terminal if the left front power window switch is pushed while operating in the EXPRESS DOWN mode, opening the relay control switch. Terminal A of the motor is also now not grounded through the left front power window switch. The window stops moving down. If the power input at terminal A of the power window control module is lost, the power window still operates. However, the power window operates without the express down feature.

Window Switch Operation

Battery voltage is applied to the window switches and the window lockout switch through the POWER WDO/SUNROOF RELAY under the following conditions:

    • The ignition switch is in the ACCY position.
    • The ignition switch is in the RUN position.
    • During the retaining accessory power (RAP).

When the UP switch in the window switch is operated, battery voltage is applied to the window motor. The motor is grounded through the DOWN contacts in the following components:

    • Window switch
    • LH front power window switch

The motor runs in order to drive the window up. When the DOWN switch in the window switch is operated, battery voltage is applied to the window motor in the opposite direction. The motor is grounded through the UP contacts in the following components:

    • Window switch
    • LH front power window switch

The motor runs in order to drive the window down.

Each motor is protected by an electronic circuit breaker. The circuit breaker opens the circuit under the following conditions:

    • A window switch is held too long with the window obstructed.
    • A window switch is held too long after the window is fully up or down.

The circuit breakers have positive temperature coefficients. The circuit breakers rest automatically when voltage is removed from the motors.