What is the sensor on the rear view mirror?

[RaptorTurboS]

I’m planning to install a dash cam directly behind the rearview mirror. However, I noticed there is a small rectangular sensor on the back left of the mirror. I tried looking everywhere in the manual and I can’t figure out what the sensor is for. I’m concerned I may block something important with the camera. Does anybody know what the sensor is for? Much appreciated!

 

[pierceography]

It's probably the sensor that controls day/night mode on your mirror. I wouldn't recommend covering it.

 

[traxem]

That’s for the self-dimming mirror. It measures the light in front of the truck and compares it to the light from behind the truck. Don’t block the sensor or put anything that emits extra light in front of it.