Bought a 1989 mustang with a car alarm. Pretty basic alarm---unlocks/locks doors, flashes park lights, shock sensor & siren. No markings on the brain what so ever. Stupid remote has no markings either. Worked fine for a few weeks. Push button and doors lock---1 beep. Push it again and doors unlock----2 beeps. I opened a door while armed and the siren went off like you would expect.
Fast forward to now---put a boost and fuel pressure gauge in the car (didn't disturb the alarm or at least didn't think I did) and now alarm doesn't want to work properly. Was beeping 3 times when I armed it and 4 times when I disarmed it. Dome light would stay on. Tried disconnecting battery multiple times and messing around with it (checking connections, wires, etc for problems too) with really no change. Today, I went out and tried it again (battery was disconnected for a day or two). This time I got one beep on arming and then 4 beeps on disarm. Then back to 3 beeps on arm and 4 beeps on disarm.
WTH! I have no info on this and have no idea how to go about diagnosing it.
HELP!!!!! Thank you.