GM Service Manual Online
For 1990-2009 cars only

When the ignition switch is in the ON position, voltage applies to through the P/W fuse to the following switches:

    • The master switch
    • The right front window switch
    • The left rear window switch
    • The right rear window switch

The master switch permanently grounds to G200.


Object Number: 474183  Size: SH

The master switch (1) contains one switch (2) for each window and is located on the left front door trim panel (4).

Depressing the left front window switch that is within the master switch will cause the down/auto down contacts to close, allowing voltage to apply to the left front window motor. The left front window motor grounds through the normally grounded up contacts of the left front window switch to G200. The motor turns and opens the window when both power and ground are supplied to the motor. The left front window motor stops once the window opens completely, via an electronic circuit breaker (ECB) within the motor. The left front window motor also stops whenever the left front window switch is released, returning the down/auto down contacts to the grounded position.

In order to close the left front window, lift the left front window switch that is within the master switch. Lifting the left front window switch causes the up contacts to close, allowing voltage to apply to the other side of the left front window motor. When closing the left front window, the left front window motor grounds through the down/auto down contacts of the left front window switch to G200. The motor turns and closes the window when both power and ground are supplied. The left front window motor stops once the window closes completely, via an ECB within the motor. The left front window motor will also stop whenever the left front window switch is released, returning the up contacts to the normally grounded position.

The left front window switch that is within the master switch also incorporates circuitry for the AUTO down feature. This allows the left front window to open automatically to the fully open position. Depress the left front window switch completely (past the detent) and release the switch. The circuitry will continue to operate the left front window motor, as described above, until the window stops. The ECB will stop the motor and the switch contacts will return to their normally grounded position. To cancel the AUTO down feature, lift the left front window switch to the up position momentarily.

When one of the passenger window switches in the master switch is depressed, voltage is supplied through the down contacts and through the appropriate switch to the motor. The motor is grounded back through the appropriate switch and the normally grounded contacts in the master switch to G200. The motor turns and opens the window when both power and ground are supplied to the motor. The motor stops once the window opens completely, via an ECB within the motor, or whenever the switch is released.

In order to close one of the passenger windows using the switch that is within the master switch, lift the window switch allowing voltage to apply through the up contacts in the master switch and the appropriate switch to the other side of the window motor. The motor is grounded back through the appropriate switch and the normally grounded contacts in the master switch to G200. The motor turns and closes the window when both power and ground are supplied to the motor. The motor stops once the window closes completely, via an ECB within the motor, or whenever the switch is released.

The other method of operating the passenger windows is through the window switch located on the appropriate door. Each switch is supplied voltage through the P/W fuse when the ignition switch is in the ON position. When any one of these switches are depressed to the down position, the down contacts of that switch apply voltage directly through that switch to the appropriate window motor. The motor grounds through the depressed switch and through the normally grounded up contacts in the master switch to G200. The motor turns and opens the window when both power and ground are supplied to the motor. The motor stops once the window opens completely, via an ECB within the motor, or whenever the switch is released. In order to close the window, lift the window switch allowing voltage to apply through the up contacts in the switch to the other side of the window motor. The motor is grounded back through the appropriate switch and the normally grounded contacts in the master switch to G200. The motor turns and closes the window when both power and ground are supplied to the motor. The motor stops once the window closes completely, via an ECB within the motor, or whenever the switch is released.

The master switch also contains circuitry for the WINDOW LOCK feature. This feature allows the right front, left rear and right rear window switches to be locked out. When the WINDOW LOCK switch is depressed to the lock position, operation of the right front, left rear or right rear window switches is not possible through any switch. The switch interrupts the path to ground for all window switches. Without a path to ground, the window switches will not operate from any switch.