Principles of Operation
PRINCIPLES OF OPERATIONLH Front Power Window Control
The LH front window motor is an 8-pin motor with integral electronics and must be initialized whenever a new window motor has been installed. When mechanical repairs have been carried out on the LH front window regulator or glass run, the LH front window motor must be de-initialized, and then initialized. The LH front window control switch sends 3 separate signals to the LH front window motor: UP, DOWN and AUTO. The LH front window control switch provides a 12-volt signal to the LH front window motor to request an up or down operation. When AUTO up or AUTO down is requested, the LH front 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 and down contacts are connected to ground and the AUTO contact is floating within the front window control switch when the switch is in the NEUTRAL position. The UP, DOWN and AUTO feeds to the LH front window motor are all low current.
The LH front window motor is splined to a nylon pinion drive gear inside a composite plastic housing, and the assembly is mounted to the drum housing of a dual rail drum and cable window regulator. The LH front window motor uses internal Hall-effect sensor feedback coupled to the internal microprocessor to determine window glass position and operate the window motor. If the Hall-effect pulses are not being received by the microprocessor, the LH front window motor will run for approximately 1/10 second each time the switch is pressed. The LH front motor contains a thermal breaker to protect the motor windings from overcurrent/overtemperature operation. Continued excessive operation of the LH front motor will cause the thermal breaker to open, causing a loss of function until the window motor cools.
The LH front window motor operates with the ignition switch in the RUN or ACCESSORY positions, or when the delayed accessory relay is active. The LH front motor is supplied with B+ power and draws a key-off load of approximately 3/4 mA. The high current required to move the window is supplied through the B+ and motor ground input. For the LH front motor to operate correctly, both power feeds and the ground feed must be intact at the LH front window motor. The LH front window motor will not lose initialization if power (B+) is removed while the LH front window is not in motion. If power (B+) is disconnected from the LH front window motor while the window is in motion, the window motor will enter position recovery mode when power is restored (AUTO up will be disabled). Position recovery mode allows proportional up (and down) movement of the window until the LH front window motor stalls the window glass into the upper header seal. If no internal or external faults are present, the window motor will automatically resume normal (full) operation.
When the LH front window motor is operating in AUTO up or AUTO down mode, movement of the LH front window can be stopped by pressing the switch to any position (UP, DOWN, AUTO up, AUTO down). The LH front window control switch must be released before the window will move again.
The LH front window motor has a security override feature. If an obstacle has been detected in the window opening as the window glass is moving upward, the window motor will automatically reverse direction and move the glass toward the fully open position (in both proportional up and one-touch up modes). This is known as "bounce-back". Once the window motor stops the glass at its bounce-back position, and within 2 seconds the switch is released, then held in the AUTO up position, the window motor will move the glass up with no bounce-back protection (security override). If the switch is released before the window glass reaches the fully closed position, the window motor will stop with bounce-back automatically enabled for the next window up movement. If the ignition switch is turned to OFF or START (without delayed accessory), the window motor will stop. The only exception is when an obstacle is detected in the window opening while delayed accessory power is not present. In this case the window motor will bounce back, then stop. Ice, contaminant buildup and environmentally induced tight spots in the LH front window seals are all possible conditions that will activate 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 will be 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 will be 50 mm (1.96 in) below where the obstruction occurred.
The LH front window control switch has illumination and illumination ground inputs, which are used to illuminate the switch when the headlamp switch is turned to the PARK or ON position (the autolamp position may also energize this input). These switch inputs do not directly affect operation of the LH front window. The LH front window control switch uses the delayed accessory power input, which is transferred to the up or down outputs when the corresponding switch contact is closed. The LH front window control switch is grounded to the chassis through the main switch ground input, which is transferred to the auto output when the corresponding LH front window control switch contact is closed. If the delayed accessory feed to the front window control switch is missing, none of the windows will function. If the main ground signal is missing, the LF auto functions will be inoperative and the remaining 3 windows will also be inoperative.
If there is an open in the LH front window control switch or the associated wiring, the related function will become inoperative. If the up contact of the switch or the associated wiring develops an open circuit, the LH front window will only operate in the down direction, or in the one-touch down mode. If the down contact of the switch or the associated wiring develops an open circuit, the LF window will only operate in the UP direction, or in the one-touch up mode. If the auto contact of the switch or the associated wiring develops an open circuit, the LF window will only move proportionally up or down.
The LF window motor will not operate if a switch error exists. A switch error is defined as UP and DOWN, AUTO input without up or down, or up, down and AUTO inputs energized at the same time. The LH front window will appear to be inoperative if a switch error is present.
A new LH front window motor will only operate in proportional up/down mode, and the bounce back feature will be disabled prior to initialization. If the switch is actuated to the auto up or auto down position and released, window movement will stop when the up or down contact in the LH front window control switch is released. If the LH front window motor is removed from the window regulator drum housing, or if a new LH front window motor is installed, it must be initialized. Refer to Window Motor Initialization.
The LH front window motor will automatically adjust to system changes throughout its life: changes in seal drag and slight changes in the full open position will occur and will be automatically compensated for. Once initialized, the LH front window motor will soft stall into the upper and lower positions contributing to extended durability of the system. If the LH front window does not seal completely in the full up position (very small gaps/non bounce-back events only), the LH front window switch can be actuated to the proportional UP position and the LH front window will be energized for a fraction of a second to fully seal and this new position will be learned.
Passenger Window Operation
Passenger windows may be raised or lowered using the LH front window control switch or the corresponding passenger window control switch. Passenger window control switches receive power when the delayed accessory relay is active and the LH front window lock switch is in the unlock position. When the LH front window lock switch is in the lock position, the passenger windows will not operate.
Delayed Accessory Power
The smart junction box (SJB) controls power to the power windows, the audio system and the power roof opening panel with the delayed accessory relay. The SJB activates the delayed accessory relay whenever the ignition switch is in the RUN or the ACCESSORY position, or when the ignition switch is changed from RUN or ACCESSORY to the OFF/LOCK position and the LH and RH front doors are closed.
The SJB will deactivate the delayed accessory feature when:
- the LF door is ajar and the ignition switch is in the OFF/LOCK or KEY-OUT position.
- the RF door is ajar and the ignition switch is in the OFF/LOCK or KEY-OUT position.
- ten minutes have elapsed since the ignition switch was changed from ACC or RUN to the OFF/LOCK position.
Rear Window Defrost
The smart junction box (SJB) controls power to the heated backlight by controlling the state of the heated backlight relay. When the rear window defrost switch is pressed, the SJB will activate the heated backlight relay. When the heated backlight relay is active, the heated backlight will be energized.
The SJB will deactivate the heated backlight relay when one of the following conditions is met:
- The rear window defrost switch is pressed when the feature is active.
- Ignition switch state is changed from RUN to OFF/LOCK.
- The 17-minute timer completes.