Electrical Security Theft System

[Fireman807]

Okay I have a 1996 Ford Mustang GT Cobra fastback and I lock the driver's door and 10 seconds after I lock the driver's door the alarm system goes off I'll put the key back in the door and it shuts off I don't know where to store or what could be wrong or how to bypass it to lock my driver's door I don't have the remote entry for it could that be could that be a reason or is it something else I need help please

 

[wmburns]

If looking for an educated guess how about the door ajar switch isn't working. The alarm "thinks" one of the doors is open. It seems to me the problem could be in either door (driver or passenger).