Mirror Sensors
 

I have a 2005 Town and Country with the auto dimming mirror feature. On my rear view mirror there is a sensor on the front of the mirror (facing rearwards), a sensor on the rear of the mirror (facing forward) and a third sensor in the mirror mount where it attaches to the windshield (also facing forward). I believe the sensor on the front of the mirror controls the auto dimming feature of the mirror itself. Does the sensor on the rear of the mirror control the light level of the dash lights such as the odometer and radio ? What does the sensor in the mirror mount do? Thanks.

no its only for the mirror itself nothing else

Mirror Sensors
 

So if I understand correctly, the auto dimming for the mirror uses the 2 sensors on either side of the mirror. On the back of the mirror there is a plug and from that plug there are 2 wires that run down to a third sensor in the base of the mirror that attaches to the windshield. What does the 3rd sensor do?

OPERATION
The ambient photocell sensor faces forward, to detect the outside light levels. A second sensor faces rearward to detect the light level received through the vehicles back window. When the difference between the two light levels becomes too great (the light level received at the rear of the mirror is much higher than that at the front of the mirror), the mirror begins to darken.

The mirror switch allows the driver a manual control of whether the automatic dimming feature is operational. When AUTO is selected a small Light-Emitting Diode (LED), to the right of the mirror switch, is illuminated. The automatic dimming feature will only operate when the ignition switch is in the On position. The mirror also senses the backup lamp circuit, and will automatically disable its self-dimming feature whenever the transmission gear selector is in the Reverse position.

NOTE: The mirror always defaults to an ON state upon ignition.

The driver side automatic dimming mirror is standard with the automatic dimming inside mirror. The signal to control the dimming of that mirror is generated by the automatic day/night inside rear view mirror circuitry. That signal is then delivered to the driver side outside rear view mirror on a hard wired circuit.

The automatic day/night mirror cannot be repaired. If faulty or damaged, the entire inside rear view mirror assembly must be replaced.