GM Service Manual Online
For 1990-2009 cars only

Circuit Operation

A permanent magnet (PM) motor operates each of the power windows. Each motor raises or lowers the glass if voltage is supplied to the motor. The polarity of the supply voltage determines in which direction the motor turns. The window switches control the supply voltage polarity.

A built-in circuit breaker protects each motor. The circuit breaker opens the circuit if a window switch is held too long and one of the following conditions exists:

    • The window is obstructed.
    • The window is fully up or down.

The circuit breaker resets only after the voltage is removed from the motor.

Left Front Window Switch Operation

Voltage is applied to the left front window switch through the PWR WDO circuit breaker and to circuit 143 when the ignition switch is in the RUN position. When any of the UP switches in the left front window switch is operated, voltage is applied to the window regulator motor. The window regulator motor is grounded through the down contact in the left front window switch. The motor runs in order to drive up the window. When any of the down switches in the left front window switch is operated, voltage is applied to the window regulator motor in the opposite direction. The window regulator motor is grounded through the UP contact in the left front window switch. The motor runs in order to drive down the window.

Right Front Window Switch Operation (2 Door)

Voltage is applied to the right front window switch through the PWR WDO circuit breaker and to circuit 143 when the ignition switch is in the RUN position. Voltage is applied to the window regulator motor when the UP switch in the right front window switch is operated. The window regulator motor is grounded through the down contact in the left front window switch. The motor runs in order to drive the window up.

When the down switch in the right front window switch is operated, voltage is applied to the window regulator motor in the opposite direction. The window regulator motor is grounded through the UP contact in the left front window switch. The motor runs in order to drive the window down.

Express Down Feature

If the down position in the left front window switch is momentarily pressed down past the first defeat, the window will travel to the fully down position. Press the left front window switch to the UP position in order to stop the window.

Lock Out Switch Operation

The left front window switch contains a lock out switch. The lock out switch removes voltage from the other window switches. This action prevents the operation of the windows from their individual switches. You may still operate the windows as usual from the left front window switch.

Window Switch Operation (4 Door)

Voltage is applied to the window switches when the ignition switch is in the ACCY or the RUN position. Voltage is applied to the window switches along the following path:

  1. Through the PWR WDO circuit breaker
  2. To circuit 143
  3. To the left front window switch
  4. Through circuit 1307
  5. To all of the switches

Voltage is applied to the right front window regulator motor through circuit 666 when you press the UP position on the right front window switch. The motor is grounded through the following areas:

    • Circuit 667
    • The DOWN contact in the right front window switch
    • Circuit 167
    • The DOWN contact in the left front window switch

The motor runs in order to drive up the window.

Voltage is applied to the right front window regulator motor when you press the DOWN position of the right front window switch. Voltage is applied to the right front window regulator motor in the opposite direction through circuit 667. The motor is grounded through the following areas:

    • Circuit 666
    • The UP contact in the right front window switch
    • Circuit 166
    • The UP contact in the left front window switch

The motor runs in order to drive down the window.

The other windows operate from their individual window switches in a similar manner.