I have a 2012 Crew and want to know what this button does on my rear view mirror. When I start the vehicle the left square always lights up. I can push the middle button and only the left square will turn on and/or off but the right one does nothing. Matter of fact I've never seen it on at any point.

I assumed it had something to do with auto dim but I haven't noticed a difference whether it's on or off.

Thanks in advance.

 

The button turns on/off the auto-dimming mirror function. The right 'square' is the light sensor that it uses to determine if it needs to dim. The right 'square' does not illuminate.

The auto-dimming function is 'on' when the left square is illuminated.

 

Thanks for your input.

 

Yes sir auto dimming... Turn it off at night with cars behind u and you'll understand!