Good afternoon and welcome to JustAnswer!!
My name is ***** ***** I have worked for a Chrysler-Dodge-Jeep dealership for 19 years and I will do my best to help.
Here is a description of the mirror:
The lighted switch on the automatic dimming inside rear view mirror provides the vehicle operator with a manual control of whether the automatic dimming feature is operational. When AUTO is selected, the mirror switch is illuminated. However, if the mirror is turned OFF manually, the mirror switch illumination is extinguished. However, the mirror will always turn back ON by default at the onset of a new ignition ON cycle. The automatic dimming mirror circuitry also senses the backup lamp circuit, and will automatically disable its self-dimming feature whenever the transmission gear selector is in the REVERSE position.
The ambient photocell sensor of the mirror faces forward, to detect the outside light levels through the windshield glass. A second headlamp photocell sensor is located in the upper right quadrant of the mirror face, to detect the light level received at the rear window side of the mirror. When the mirror control circuitry detects that the difference between the two sensed light levels has become 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. A thin layer of electrochromic material between two pieces of conductive glass make up the face of the mirror.
On vehicles equipped with an optional driver side automatic dimming outside rear view mirror, the signal to control the dimming of that mirror is generated by the automatic dimming inside rear view mirror circuitry. That signal is then delivered to the driver side outside rear view mirror on two hard wired circuits
If you shine a light from the front will it lighten up? If yes then the mirror is working... Do you have a dark tint strip across the front windshield?