Electrically Heated Systems
WARNING: This page is about a different car, the 2006 Dodge Viper. However, it is still accessible from the selected car via links, so may be relevant.
The rear window defogger button located on the HVAC control controls the ground for the rear window defogger relay coil. The BCM supplies the power to the Rear Window Defogger relay coil. The defogger LED will illuminate when the defogger function is on. The defogger will function for 10 minutes or can be cycled off sooner by pressing the defogger button again.