Windows: Description and Operation

The power window motors are permanent magnet DC motors. These motors move the window up and down depending on which way the voltage is applied to them. The LH window switches apply ground to both motor terminals when at rest (the position shown in the schematic). When a switch is moved to the UP or DN position with the Ignition in RUN, one of the contacts moves to supply battery voltage to the motor which then drives the window up or down. The RH window switch works in a similar manner.

The express down feature causes the LH front window to go completely down after a single momentary touch of the LH switch button. The express down position of the HI switch is reached by pushing the button beyond the DN position.

When the express down position is contacted, a solenoid in the express down module holds the switch in the DN position. The window may be stopped by momentarily pushing the switch to the UP position.

The Express Down Module monitors the power window motor current through a resistor. It releases the down switch and stops the window when the current increases or when it becomes zero. An increase in current occurs when the motor stalls at the end of its travel. Zero current occurs when the switch is pushed to the UP position, removing ground from the motor.

Each motor is protected by a built-in electronic circuit breaker PTC. If a window switch is held too long with the window obstructed or after the window is fully up or down, the PTC resistance increases. The resistance returns to normal after voltage is removed from the motor terminals.