The body control module (BCM) controls the operation of the power window relay, which controls the power supply to the window motors and also the automatic down function of the windows.

The system is active when the LEDs in the center console window rocker switches illuminate. The switches are only operational when the ignition is ON.

NOTE: If the BCM has entered battery saver mode and the ignition is switched off, the power supply is disconnected from the window system.

The system is inactive when the window switch LEDs are not illuminated.

Automatic down operates when either of the window's DOWN buttons is pressed for more than 0.4 second but less than 1 second (i.e. momentarily). To control the Automatic Window feature, press the window switch to the DOWN position (momentarily) and release it. The window will continue to lower until it reaches the fully down position. The automatic down feature can be interrupted by operating the window UP or the DOWN switch momentarily. The window stops immediately the UP switch is lifted, but only stops moving when the DOWN button is released.

A permanent-magnet motor operates each of the power window mechanisms to raise or lower the window glass. The direction in which the motor turns depends on the polarity of the voltage supplied to the motor terminals. The power window switches control the voltage polarity.

The purpose of the body control module (BCM) is to monitor the operation of the switches and to sense when either the Automatic Window Down feature is to be activated or de-activated and to determine how long to energize the Automatic Window Down relay to complete the window's travel.

The window control switches on the console are mechanically interlocked so that they can only be operated in one direction at a time. When the DOWN switch is pressed, battery voltage passes through the DOWN switch contact to the respective WDO_DN terminal on the body control module (BCM). This voltage not only passes through to the motor to commence it moving the window down, but also passes to the BCM's AUTO_WDO_DN input. This means that when the window button is pressed, the BCM checks to see if the button activation time is greater than 0.4 second and less than 1 second (which represents a momentary press). If it is a momentary press, then the BCM energizes the AUTO DOWN WINDOW relay to complete the circuit until the window has reached the fully DOWN position. The BCM also calculates the time required to keep this relay energized to complete the process. When window movement is completed, the BCM de-energizes the relay, and the window control circuit reverts to normal. If the driver activates either the UP or the DOWN buttons momentarily while the window is traversing downwards, the window will stop moving downward and remain at that point. If the UP button is raised continuously, the window will first stop, the relay will de-energize and the window will then move upwards as directed by the UP button. There is no AUTO UP function associated with window movement. When the UP button is lifted while the window is down, the battery polarity presented across the window motor is reversed.

The body control module (BCM) uses this input signal to determine when the ignition switch is turned to the ignition or to the start position. When this occurs battery voltage via the ignition switch is applied to the BCM. When the BCM receives an ignition ON input signal, it energizes the Power Window Relay by grounding the relay coil. With the relay energized, the relay contacts close and power is applied to the power window switches. The opposite side of each window switch LED is connected to ground, causing the LEDs to illuminate, thereby indicating that the power window electrical system is active.

When the Window DOWN switch is pressed, voltage passes to body control module (BCM) terminal X4-26 via the Power Relay R22 contacts, circuit 638 and the Driver Window DOWN switch contacts X1-13. From BCM terminal X4-26, the current passes through the normally closed contacts of the BCM Driver Window Relay to terminal X1-A PF the Driver Window Motor via BCM terminal X4-25 and circuit 165. Terminal X1-B of the motor is grounded through circuit 164, the Driver's Window UP switch contacts and circuit 650. The BCM microprocessor senses the length of time that the drivers window button is pressed DOWN at terminal X4-26. If the window DOWN switch is momentarily pressed for more than 0.4 second and less than 1 second, the BCM energizes the LTFR Window Relay until the window lowers fully.

The voltage from the Power Window Relay R22 is applied through terminal X1-8 of the Passenger Window DOWN switch contacts to body control module (BCM) terminal X4-12, via circuit 167. This voltage then passes through the BCM relay's normally closed contacts to BCM terminal X4-13 to the window motor terminal X1-A via circuit 667. Terminal X1-B of the window motor is connected to ground via circuit 666 and switch terminals X1-7 via the UP switch contacts to ground via terminal X1-9 and circuit 650. NOTE: The power window motors each contain an internal overload thermal breaker which is activated (opens) if the power window switch is held in the UP or DOWN position for more than 20 seconds. This prevents overheating of the power window motor windings. After a cool down time of approximately 40 seconds, the thermal breaker closes again and allows normal motor operation.

By lifting and holding up the Driver Window UP button, battery voltage from the Power Window Relay is applied to the drivers window motor through switch terminal X1-12 and circuit 164. Circuit 165 is connected to ground through body control module (BCM) terminal X4-25, terminal X4-26, circuit 1136, the DOWN power window switch contacts and circuit 650. The lifting of the Driver Window UP switch causes the motor armature to rotate and raise the window while the button remains lifted. PASSENGER WINDOW-UP INPUT SIGNAL: By lifting and holding up the Passenger's Window UP button, battery voltage is applied to through the centre console switch terminal X1-7 and circuit 666 to window motor terminal X1-B. Circuit 667 is connected to ground through BCM terminal X4-13, terminal X4-12, circuit 167 and the DOWN switch contact via X1-9 to circuit 650. This causes the motor armature to rotate and raise the window while the Passenger Window UP button remains raised.

The body control module (BCM) monitors the state of the Driver Window UP and Driver Window DOWN switches at X4-15 and X4-26 respectively. When the Automatic Window DOWN feature is in progress, if the Passenger Window UP switch is operated for any length of time, the window stops immediately as the motor is immediately presented with battery voltage across both terminals. The BCM senses this switch voltage on X4-15, and de-energizes the relay to permit the polarity across the motor to change and for the window to commence winding upwards. NOTE: If the Driver Window DOWN switch is pressed while Auto Window DOWN feature is in progress, the BCM senses this request at X4-26, but will not de-energize the relay until the Driver Window DOWN switch is released.

The body control module (BCM) monitors the state of the Passenger Window UP and Passenger Window DOWN switches at X4-14 and X4-12 respectively. When the Automatic Window DOWN feature is in progress, if the Driver Window UP switch is operated for any length of time, the window stops immediately as the motor is immediately presented with battery voltage across both terminals. The BCM senses this switch voltage on X4-14, and de-energizes the relay to permit the polarity across the motor to change, and for the window to commence winding upwards. NOTE: If the Passenger Window DOWN switch is pressed while Auto Window DOWN feature is in progress, the BCM senses this request at X4-12, but the BCM will not de-energize the relay until the Driver Window DOWN switch is released.