Mirrors: Description and Operation
HEATED MIRRORSElectrically heated outside rear view mirrors are optional equipment on this model. Heated mirrors are available with Memory Mirrors and Rear Window Defogger only. 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 HEATED GLASS - DIAGNOSIS AND TESTING). If the outside mirror heating grids are inoperative, but the rear window heating grid is operating as designed, (Refer to HEATED MIRRORS - DIAGNOSIS AND TESTING) for diagnosis of the outside mirror heating grids.
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 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.
POWER MIRROR SWITCH
The mirror switch on the door trim panel operates both the outside rear view mirrors. On vehicles equipped with Memory/Heated Seats, the Memory Heated Seat Mirror Module (MHSMM) activates the mirror motors in recall mode.
Position sensing potentiometers built into each mirror's vertical and horizontal motor assembly. These potentiometers provide a sense voltage to the MHSMM that indicates where the actual location of each mirror is. If a memory position is set, the values of the potentiometers at that location are stored in memory.
MEMORY SYSTEM
The memory system consists of power left front seat, power mirrors and radio presets. The memory heated seat/mirror module (MHSMM) also includes the heated seat function. The module is located under the left front seat and receives input from: left manual 8-way seat switch, left seat position sensors, memory switch, both heated seat switches, both heated seat negative temperature coefficients (NTC's) thermistors), PCI bus circuits, and the power mirror sensors. The module uses these in- puts to perform the following functions: position the drivers memory seat, both exterior mirrors, actuate the drivers and passenger heated seat heater and send the memory location over the PCI bus.
When a memory button is pressed (either # 1 or # 2) on the memory switch the MHSMM sends a message to the BCM which in turn sends a recall message to the MHSMM and the PCI radio. They will in turn position the drivers seat and both mirrors along with setting the radio presets. If the drivers seat or either exterior mirrors are inoperative from their own respected switches, use the service information and schematic to diagnose the problem. This addresses the memory problems only and it is assumed there is not a basic component failure.
Memory Mirrors
Each outside mirror has a vertical and a horizontal position sensor. The MHSMM provides a 5-volt reference to each position sensor. The sensors share a common ground circuit. The MHSMM monitors the position of the mirrors by measuring the voltage of each signal. When a memory position is set, the MHSMM monitors and stores the position of the outside mirrors. The MHSMM adjusts the mirrors to the appropriate positions when a memory recall message is received from the RKE or is requested from the memory switch.
The power mirror switch during non-memory operation operates both mirrors independently of the MHSMM.