System Operation
System Diagram - Rear Window Defrost
Item | Description |
---|---|
1 | BJB |
2 | HVAC Module |
3 | MS-CAN |
4 | Rear Window Defrost Grid |
5 | GWM |
6 | BCM |
7 | HS-CAN1 |
8 | LIN |
Network Message Chart - Rear Window Defrost
BCMC Network Input Messages
Broadcast Message | Originating Module | Message Purpose |
---|---|---|
Rear window defrost request | HVAC module | When the BCM receives the rear window defrost request message, a request is sent through a LIN to the BJB to activate the rear window defrost system. |
Power Window Operation
Voltage is supplied to the power window system whenever the ignition is on, or whenever the ignition is changed from on to off while the LH and RH front doors are closed. The voltage supplied to the power window system is removed when:
The front power windows operate when the ignition is on and/or the accessory delay relay (non-serviceable and located in the BCM ) is active. The driver front power window is equipped with a one-touch down feature (controlled by the driver door window control switch integral electronics). This allows the driver door front power window to be completely lowered when the control switch is pressed to the second detent position and then released.
Rear Passenger Windows Lock Out
When the lock out switch (part of the driver window control switch) is in the LOCK position, the rear passenger power windows only operate from the driver window control switch.
Rear Window Defrost
The rear window defrost system only operates when the engine is running. When the rear window defrost switch is activated, the HVAC module sends the request message to the BCM and then through a LIN to the BJB . The BJB activates the rear window defrost relay (integral to the BJB ). When the rear window defrost relay is activated, the rear window defrost grid(s) are energized. In some cases, the rear window defrost system may automatically activate as an extra load for accelerated engine warm-up. However the rear window defrost status LED remains off unless the rear window defrost switch is activated.
The BJB deactivates the rear window defrost relay when any of these conditions is met:
Component Description
Driver Window Control Switch
The driver window control switch receives voltage whenever the accessory delay relay is active. The driver window control switch:
Front Passenger Door Window Control Switch
The front passenger window control switch contains momentary contacts (normally closed). When the front passenger window control switch is activated, voltage and ground (provided from the driver window control switch) are supplied to operate the power window motor in the desired direction.
Rear Door Window Control Switch
The rear window control switches receive voltage whenever the rear passenger window lock-out switch (part of the driver window control switch) is in the UNLOCK position. Ground is provided to the rear window control switches through the driver window control switch.
The rear window control switch contacts are normally closed. When the rear window control switch is activated, voltage and ground are supplied to operate the power window motor in the desired direction.
Window Regulator Motor
The window regulator motor(s) are bi-directional. Window direction is determined by the polarity of the voltage being supplied to the motor from the associated door module.
BCM
When a rear window defrost request message is sent to the BCM , the BCM sends a request to the BJB through a LIN to activate the rear window defrost system. PMI is required whenever installing a new module.
HVAC Module
The HVAC module contains the rear window defrost switch. PMI is required whenever installing a new module.