Rear Window Defrost

Glass, Frames and Mechanisms

Principles of Operation

Rear Window Defrost

When the rear window defrost switch (integral to the Front Controls Interface Module (FCIM)) is pressed, a message is sent to the HVAC module through the Controller Area Network (CAN). When the HVAC module receives the rear window defrost request, it will activate 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.

The HVAC module will deactivate the rear window defrost 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 10 minute timing function is completed.


Delayed Accessory Power

The accessory delay relay (located in the Smart Junction Box (SJB)) supplies voltage to operate the power windows. The SJB activates the accessory delay 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 doors are closed.

The SJB will deactivate the accessory delay relay 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.


Convertible Power Rear Quarter Window Operation

For convertible, when the convertible top switch is operated (to raise or lower the convertible top), the Body Control Module B (BCM-B) sends a signal to the window motors to activate a full down operation of all 4 windows. The BCM-B will disable/inhibit the rear quarter window control switch from operating the rear quarter windows when the convertible top ajar switch indicates the convertible top is not in the full UP or full DOWN position.