It could have an anti-theft diode built in the alarm system to prevent the car from being "hot wired" and stolden. It may have been trippedwhen the car was hit. We once had a vehicle that had one of them. I don't know exactley where there at, but an alarm company should be able to tell you or locate it for you. I hope I cwas able to help you a little.
Robert
January 2010