Rear Window Defrost

When the rear window defrost switch (integral to the HVAC module or Front Controls Interface Module (FCIM), if equipped with navigation system) is pressed and the engine is running, the HVAC module will activate the rear window defrost relay located in the Battery Junction Box (BJB). When the rear window defrost relay is active, both the rear window defrost grid and heated mirror elements will be energized.

The HVAC module will deactivate the heated grid 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

Feature inputs: 

• Ignition switch RUN position (12V on both RUN and RUN/ACC inputs)
• Rear window defrost switch (momentary contact to ground when switch is pressed)

Feature outputs: 

• Rear window defrost relay control (grounded when activated, open circuit when deactivated)