Rear Defogger and Heated Mirrors

The mirror heat function is linked to the Rear Window Defogger. When the rear defogger is active, a Class 2 bus message is sent from the HVAC Control Module (HCM) to the Driver Door Module (DDM). The DDM activates the drivers side outside rear view mirror heating element to clear the mirror of mist or frost. The DDM sends a Simple Bus Interface (SBI) message to the passenger door module (PDM) to heat the passenger side outside rear view mirror. The mirror heating element will not de-ice a mirror except at temperatures just below freezing. Mirror heat status is provided from the scan tool.