Heated Mirrors: Operation
WARNING: This page is about a different car, the 2002 Dodge Intrepid, 2002 Chrysler Intrepid, 2002 Chrysler Concorde, and 2002 Chrysler 300M. However, it is still accessible from the selected car via links, so may be relevant.
The heated mirror is controlled by the rear window defogger switch. The only time that the heated mirror is on is when the rear window defogger is on. The mirror should become warm to the touch. For more information and testing, see REAR WINDOW DEFOGGERS & HEATED MIRRORS - CONCORDE, INTREPID & 300M article.