I have a car alarm?!?!

My friend has a 1994 chevrolet corsica.  Today he found out that he has a car alarm....the hard way...   He opened the door, and it sounded.  He doesn't have a remote to disengage the alarm, and there doesn't appear to be any kill switch, at least without minor probing...  The car is equipped with a starter relay that keeps it from starting when sounding, either that, or there is a short in the system.  He's never had the problem before. When the horn is honked, the alarm sometimes turns off too.   How do we diagnose our problem, and get the car to start?  Again, there is no remote to disengage or engage the alarm, and this is the first time he realized he even had an alarm!1994 Chevy CorsicaPower door locks, power windows....~wayland

find the brain and pull the fuse this should solve the no start problem if it doesn't find the yellow or purple wire coming out of ing switch follow it to the relay and reconnect wiresgood luck

kirk