2007 Mustang, Motion sensor on stock security system?

Yes the sensors are in the overhead light console. They look like tiny speakers and one points driver side the other to the passenger. It is an interior intrusion detector. I also found out recently that my car has a tilt sensor. I was jacking up the car and when the front wheel was about an inch off the ground the alarm went off. :bigthumbsup

Here's a pic where you can see the one on the passengers side. The thing in the middle is where I installed my microphone for the AVIC Z2.