Principles of Operation

One-Touch Up/Down, Front Windows 

The LF (and RF, Navigator only) window motor contains integral electronics. The window control switch provides low current 12-volt signals to the motor to request an up or down operation. When auto up or auto down are requested, the window control switch provides a 12-volt signal on the up or down line and a ground signal on the auto line simultaneously. The up, down and auto contacts are floating within the front control switch(es) when in the neutral position.

The motor uses internal Hall-effect sensor feedback to determine window position and operate the window. If the Hall-effect pulses are not being received, the motor runs for approximately one-tenth of a second each time the switch is pressed. The motor contains a thermal breaker to protect the motor windings from overcurrent/overtemperature operation. Continued successive operation of the motor causes thermal breaker to open, resulting in a loss of function until the motor cools.

The window motor operates with the ignition in the RUN or ACC modes only (and delayed accessory) and is sensed via the delayed accessory input. All of the high current required to move the window is supplied through the B+ and motor ground inputs.

During an auto up or auto down function, movement of the window can be stopped by actuating the switch to any position (up, down, auto up, auto down). The switch must then be released before the window carries out the next commanded movement.

When an obstacle has been detected in the window opening as the window is moving upward, the window automatically reverses direction and moves toward the fully open position (in both up and one-touch up modes). This is known as "bounce-back". Once the window stops at its bounce-back position, and within 2 seconds the switch is released then held in the auto up position, the window travels up with no bounce-back protection (security override). If the switch is released before the window reaches fully closed, the window stops with bounce-back automatically re-enabled for the next window up movement. If the ignition is turned to OFF or START (without delayed accessory), the window stops. The only exception is when an obstacle is detected while delayed accessory is lost. In this case the window bounces back, then stops. Ice, contaminant buildup and environmentally induced tight spots in the window seals are all possible uses for the security override feature.

If an obstruction occurs between 4 mm (0.15 in) and 200 mm (7.87 in) of window opening, the bounce-back position is 250 mm (9.84 in) of window opening. If an obstruction occurs at a position greater than 200 mm (7.87 in) of window opening, the bounce-back position is 50 mm (1.96 in) below where the obstruction occurred.

The window motor retains its initialization (memory) if power (B+) is removed while the window is not in motion. If power (B+) is disconnected from the window motor while the window is in motion, the motor enters position recovery mode when power is restored (auto up and auto down functions are disabled). Position recovery mode allows down (and up) movement of the window until the window motor stalls the window glass in the full DOWN position. If no internal or external faults are present, the motor automatically resumes normal (full) operation.

A new window motor does not function in one-touch up mode prior to initialization. The motor responds to an up or down switch actuation only and bounce-back is disabled. If the switch is actuated to the auto UP or auto DOWN position and released, window movement stops when the up or down contact in the master window control switch or passenger window control switch is released. If the window motor is removed from the window regulator drum housing, or if a new window motor is installed, the window motor must be initialized. Refer to Window Motor Initialization .

The window motor automatically adjusts to system changes throughout its life: changes in seal drag and slight changes in the fully OPEN position occurs and is automatically compensated for. Once initialized, for the most part, the window motor soft stalls into the lower position contributing to extended durability of the system. If the window does not seal completely in the full UP position, the window switch can be actuated to the UP position and the window can be energized long enough to fully seal. If the window does not travel fully down, the window switch can be activated to the DOWN position and the window can be energized long enough to travel to the full DOWN position. In both cases, the new positions can be learned.

Rear Window Defrost 

When the rear window defrost switch (integral to the FCIM) is pressed, the request message is sent through the I-CAN to the IC. The IC sends the request message to the BCM through the HS-CAN. The BCM finally sends the request through the MS-CAN to the HVAC module, which activates the rear window defrost relay located in the Battery Junction Box (BJB). When the rear window defrost relay is active, the rear window defrost grid will be energized.