under the rear view mirror. I was in my g/f's mom's 325 and i noticed a red cap type of thing under the rear view mirror. What is it?

Ejection button. Dont push. actually, i'm guessing, but maybe its for the alarm system? autodimming mirror? anyone?

Depending on what year 325 it is, I believe the little red cap thing is the sensor for the remote key fob. At least that's what it was in a grand cherokee I once had.

It does two things:

1. It wiill blink when the alarm system has been set. This is to deter
undesirables, thieves....etc.

2. It also receives the key fob signal for the alarm system.

Hope this helps....

ML

I also think it may be so big just for looks. Maybe if is enlarged to show off the alarm system, as stated above. I know that it also receives the key fob signal.