GM Service Manual Online
For 1990-2009 cars only

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.

Left Front Window Switch Operation

Voltage is applied to the left front window switch through the accessory power relay when the ignition switch is in the RUN or ACCY 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.

Express Down Feature

If the down position in the left front window switch is momentarily pressed down past the first detent, the window will travel to the fully down position. Lift the left front window switch to the UP position in order to stop the express down of the window.

Lock Out Switch Operation

The left front window switch contains a lock out switch. The lock out switch creates an open in the wire leading to ground from the other window switches. This action prevents the operation of the windows from their individual switches. You may only then operate the left front window from the switch.

Window Switch Operation

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: Through the Accessory Power Relay. From there voltage is supplied through SP252 to all of the switches. From the switch it proceeds to the corresponding motor. Ground path goes from the normally closed switch to the LH Window/Door Lock Switch, to G200.