Theory Of Operation
WARNING: This page is about a different car, the 2020 Jeep Renegade. However, it is still accessible from the selected car via links, so may be relevant.
When the Body Control Module (BCM) receives an input from the Upper Switch Bank, indicating the Rear Window Defogger is requested, the BCM will provide a ground signal through the Defogger Relay Control circuit to the Rear Window Defogger Relay, located in the Power Distribution Center (PDC) Assembly, which activates the relay. When the Rear Window Defogger Relay is activated, the relay provides battery voltage through the Rear Window Defogger Control Output circuit, to the Rear Window Defogger, which activates the Rear Window Defogger system.