88 GTU. when I get out of the car, not locked, about 30 seconds, alarm goes off. Getting in the car, not locked, open it up and alarm goes off. I think I read once there is a way to reset?

 

stock security system or aftermarket???

If it is the stock system, it will not arm, unless you lock the car with the inside latches, and hold the handle up when closing the door.

 

It is the stock alarm. That's what is puzzling. I understand locking it from inside to arm it, but it is going off when it is not locked. I just got out of the car, closed the door and it went off for no reason.

 

That is not normal operation, so you might want to double check that it is not an aftermarket system.

I would also clean the latch switches.

 

Yep, those little plungers in the door are just switches that tell the car if the doors are closed or not. Over time they can get gunked up with crap and make poor contact. Clean 'em out