Can anyone tell me where the sensor is that controls the dimming system for the headlights on a 2007?

 

I just learned the answer to this question myself. Its in with the flashing light on top of the dash. The one for the PATS system. Try it. Go out in the day time turn your truck on an hold your hand over the light. Headlights will come on.

 

what is the mod in front of the rearview mirror?? high/low auto dim?

 

compass is that weird box thing on the rear-mirror. the face of the rear mirror has a light gathering electrode to sense when to auto-dim.