Principles of Operation
PRINCIPLES OF OPERATIONThe power window system will only operate if:
- the ignition is in the RUN or ACC position.
- the accessory delay feature is in the active mode.
NOTE: The smart junction box (SJB) may also be identified as the generic electronic module (GEM).
LH Front Power Window Operation
The power window system operates under the control of the accessory delay relay. The SJB grounds the relay coil to provide power to the power window system.
The power window system can be operated from the LH front window control switch or from the window control switches located on each door panel. The LH front window control switch has 2 modes of operation for the LH front power window, manual and auto. All other windows operate in the manual mode only.
Manual mode moves the window downward until the switch is released. The LH front power window will operate in the manual mode when the LH front window control switch is pressed to the first detent position.
Auto mode provides the one-touch down (OTD) feature for the LH front power window. The OTD function allows the LH front power window to be completely lowered when the LH front window control switch is pressed to the second detent position and then released. OTD is controlled by the LH front window control switch.
The power window system will only operate if:
- the ignition is in the RUN or ACC position.
- the accessory delay feature is in the active mode.
Heated Rear Window
The heated rear window is controlled by the SJB and the HVAC module - electronic manual temperature control (EMTC) or HVAC module - electronic automatic temperature control (EATC). The heated rear window switch is integral to the HVAC module.
For vehicles equipped with HVAC module - EATC, when the heated rear window switch is pressed to the ON position, the HVAC module - EATC sends a message through the controller area network (CAN) to the SJB. When the SJB receives the heated rear window ON message, the SJB starts a 10-minute timing function, and grounds the heated rear window relay coil control circuit, which is hardwired to the SJB. When the heated rear window relay is active, battery voltage is sent to the heated rear window grid through circuit CRD06 (BN/YE). The heated rear window grid is grounded through circuit GD150 (BK/WH).
For vehicles equipped with HVAC module - EMTC, when the heated rear window switch is pressed to the ON position, the HVAC module - EMTC sends a ground signal to the SJB through circuit CRD09 (DB/GY). When the SJB receives a ground signal through CRD09 (DB/GY), the SJB grounds the heated rear window relay coil control circuit, which is hardwired to the SJB. When the heated rear window relay is active, battery voltage is sent to the heated rear window grid through circuit CRD06 (BN/YE). The heated rear window grid is grounded through circuit GD150 (BK/WH).
The SJB will deactivate the heated rear window relay when any of the following conditions have been met:
- The rear window defrost switch is pressed when the feature is active.
- The ignition switch state is changed from RUN to OFF/LOCK.
- The SJB 10-minute timing function completes.
Front Windshield Defrost
The heated windshield is controlled by the SJB and front windshield defrost switch. The front windshield defrost will only operate when the engine is running. When the front heated window switch is pressed to the ON position, a ground signal is sent to the SJB. When the SJB receives the ground signal, the SJB applies voltage to the right and left heated windshield relay coil control circuit, which is hardwired to the SJB. When the right and left heated windshield relays are active, battery voltage is sent to the front windshield defrost grid.
Power Rear Window
NOTE: The power rear window motor is not on the multiplex link.
The power rear window motor is an 8-pin motor with integral electronics. The power rear window control switch is located in the overhead console and provides a positive voltage signal to the motor to signal an open or close request. The integral electronics on the motor allow the power rear window to be moved to 3 positions: fully open, fully closed and vent (approximately 50.8 mm [2 in] down from fully closed).
When the power rear window is in the fully closed position, pressing and releasing the control switch in the down direction will lower the rear window to the vent position. Pressing and releasing the control switch again in the down direction will lower the rear window to the fully open position. When the rear window is in the fully open or vent position, pressing and releasing the control switch in the up direction will return the rear window to the fully closed position.
The power rear window motor plastic pinion gear is mated to the drum housing of a single rail drum and cable window regulator. The motor is attached to the plastic drum housing by 3 screws. The motor uses internal Hall-effect sensor feedback coupled to the microprocessor, to determine window position and operate the power rear window. If the microprocessor is not receiving the Hall-effect sensor pulses, the motor will run for approximately half a second, then enter error mode (window will become inoperative). The motor contains a thermal breaker to protect the motor windings from over-current/over-temperature operation. Continued successive operation of the motor will cause the thermal breaker to open, causing a loss of function until the power rear window motor cools. If this occurs, when the motor cools it will be in position recovery mode. Simply press the down switch momentarily and the power rear window will stall in the full down position. Full functionality will then be restored.
The power rear window motor operates only with the ignition switch in the RUN/ACC position, or when the accessory delay relay is active and is sensed by the accessory delay relay and logic ground inputs. The motor is supplied with battery power and draws a key off load of approximately 0.5 mA. All of the high current required to move the window is supplied through the battery and motor ground inputs. The loss of both logic and motor ground will cause this system to become inoperative. For correct functionality, both power feeds and one ground feed must be intact at the power rear window motor.
If a down command is selected while the ignition switch is in the RUN/ACC position, and the ignition switch is turned to OFF or START without accessory delay relay power enabled, the window will move to the fully open or vent position and stop. If an up command is selected while the ignition switch is in the RUN/ACC position, and the ignition switch is turned to OFF or START without accessory delay relay power enabled, the window will move down to either full open or vent.
If an obstacle is detected in the power rear window opening as the window is closing, the window will automatically reverse direction and move toward the fully open position. 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 up position, the window will travel up with no bounce-back protection (security override). If the ignition switch is turned to OFF or START without accessory delay power enabled, the window will reverse direction with bounce-back re-enabled. Ice, contaminant buildup and environmentally induced tight spots in the window seals are all possible uses for the security override feature.
If power (B+) is disconnected from the power rear window motor while the window is in motion, the motor will enter position recovery mode when power is restored. Position recovery mode allows up movement of window in 15 mm (0.6 in) increments and the down switch will move the window in a one-touch down mode until it stalls in full down. If no internal or external faults exist, the motor will automatically resume normal operation.
If the power rear window control switch, or its associated wiring, develops an open circuit, that function will become inoperative. If the open contact or associated wiring develops an open circuit, that function will become inoperative. If the open contact or associated wiring develops an open circuit, the window will only travel to the fully closed position. If the close contact or associated wiring develops an open circuit, the window will only travel to the vent or fully open position.
The power rear window motor will suspend normal operation if a power rear window control switch error exists. A control switch error is defined as open and close energized at the same time. The window will be inoperative if a control switch error is present.
If the motor is removed from the window regulator drum housing, or if a new motor is installed, the window must be initialized. A new motor will be in error mode and inoperative until initialized. Refer to Window Motor Initialization - Rear. Testing and Inspection
The power rear window will automatically adjust to system changes throughout its life. Changes in seal drag and slight changes in the fully closed position will occur and are automatically compensated for. Once initialized, the motor will soft stall into the lower position contributing to the extended durability of the system.