Originally Posted by onehundred80
There is a window on the back for the sensor, back being the opposite side to the mirror, you always look at the front of mirrors, unless you don't like what you see of course.
On my 300 there is a green light on the front.
The first post says to cover the sensor on the back to test if it is working, no mention is made of the front window.
The sensor toward the windshield is the daylight sensor.
The sensor toward the rear ( mirror side ) is the dimming sensor.
I too have the green light on my 2002 Concorde Limited mirror, wish there WAS one on the XF autodimmer, but noooooooo .....
1. cover the windshield side sensor ( make it think it is night time )
2. shine a flashlight on the mirror side sensor, the mirror should dim down.