black widow alarm chirps 4 times

I have a black widow alarm in an 86 Mustang GT. I Don't know what the model # is but it is a 2-way. I will get it tomorrow. If I have it arm silently it will still chirp 4 times. If I arm it normally it will chirp two times then chirp 4 more times. It will disarm without the extra chirps. I assume that it is letting me know that 1 protection zone is being bypassed but it doesn't show the zone on the key chain display. The only zone that is connected is the dome light circuit. If I test it by opening a door it sounds off so I know that is working properly. The shock sensor is not plugged into it. The install booklet doesn't say what to do if it beeps 4 times. It only mentions that it is a zone problem. Anyone familiar with these systems?

plug in sensor ,to me its a defective sensor  you need to plug  in sensor  also tigger zone ,had trouble with the models 1800 ,and the x5 modelsdragon