Alarm Fault Message

I have a 95 DSE, and everytime I enter the key into the ignition slot I receive a messgae saying I have an alrm fault. The same thing occurs when I try and dead lock the doors, and I get the double beep error.

I assume that one of the sensors is faulty, and wondered if there is any way I can find out which one, or what the fault is.

Any thoughts would be gratefully received.
F_P