Grand Cherokee 2WD V8-4.7L VIN J (2004)
Heated Element: Description and Operation
HEATED MIRRORS
Electrically heated outside rear view mirrors are optional equipment on this model. These mirrors feature an electric heating grid located behind
the mirror glass of each power operated outside rear view mirror. These heating grids consist of a single resistor wire routed in a grid-like pattern
and captured between two thin sheets of plastic. When electrical current is passed through the resistor wire, it produces enough heat energy to clear
the outside mirror glass of ice, snow or fog. Battery current is directed to the outside mirror heating grid only when the rear window defogger
switch is in the ON position.
If the outside mirror heating grids and the rear window heating grid are all inoperative, (Refer to ELECTRICAL/HEATED GLASS - DIAGNOSIS
AND TESTING - REAR WINDOW DEFOGGER SYSTEM). If the outside mirror heating grids are inoperative, but the rear window heating grid
is operating as designed, (Refer to ELECTRICAL/HEATED MIRRORS - DIAGNOSIS AND TESTING).
The heating grid behind each outside mirror glass cannot be repaired and, if faulty or damaged, the entire power mirror unit must be replaced.
Refer to Power Mirrors for the procedures.
The outside mirror heating grids are energized and de-energized by the Driver Door Module (DDM) and the Passenger Door Module (PDM)
based upon the rear window defogger switch status. The Body Control Module (BCM) monitors the rear window defogger switch. When the BCM
receives an input from the switch, it sends a defogger switch status message to the DDM and the PDM over the Programmable Communications
Interface data bus. The DDM and PDM respond to the defogger switch status messages by energizing or de-energizing the battery current feed to
their respective outside rear view mirror heating grids.
