Crazy factory alarm

I have a 89' GTUs w/ a turbo motor. It has the factory alarm. Heres the problem. First off I think the door or lock has been worked on because it really doesnt work right in the first place. Turn it to the left and the door unlocks and the alarm light comes on... will not turn to the right (pass. door works fine right and left). So what ive been doing is just locking the door from the inside and shuting it. But for some reason it keeps going off at random. Recently ive tried leaving it unlocked but it went off anyway. One other thing ive noticed is that the alarm activation BEEP goes off speraticly sometimes when opening the door. Ill open the door and it will beep a few times with some corrisponding light flashes. I plan on just taking the door panel off and checking the connections and checking the door lock. Also I have a hornet alarm off my old car i might put in it to replace this one. But my main questions are, is there anything i should know about the factory alarm: do's dont's and qwerks.... and how hard is it to put in an aftermarket alarm and get around the old one/deactivate the stock one. Thanks ahead of time.

It's not hard at all to install an aftermarket alarm and disarm the OEM one. I do it all the time. Just make sure to buy a good alarm and not some cheap one. DEI brand is the way to go.

...But for some reason it keeps going off at random. Recently ive tried leaving it unlocked but it went off anyway...

I have had 3 second-gens. One in the past and two currently. Two have been fine, but my '90 convertible has a "quirky" alarm, too. It occasionally goes off for no reason at all. Although I've never had it go off when it wasn't armed.

FWIW, I have never used the key to arm the alarm. Just press down on the door lock, and hold the door handle up as I close the door.

IMO the factory alarms are crap anyway. My first one (no longer have it) was broken into. The guy picked the door lock, which disabled the alarm right then and there. I have only had the convertible a couple of weeks and (especially with the "quirk") it is going to get an aftermarket unit.

hm... ther's something fishy about ford... my ranger's alarm used to do that same thing... and then it just died! about once every 2 months or so it'll come on for a split second and then die again... wierd

hm... ther's something fishy about ford... my ranger's alarm used to do that same thing... and then it just died! about once every 2 months or so it'll come on for a split second and then die again... wierd

I'm not sure there's a legitimate connection there. Ford and Mazda have been "partnering" for a long time (my '81 Courier was actually a Mazda), but were the older Rangers built over there as well?

my ranger is a 2000, i know there's a 95% chance there is no connection. i just found it wierd that mine wasn't the only one.

Thanks for the feedback... im just going to jack my alarm out of my POS taurus (Hornet Alarm) and put it in my RX7. How do you disable the factory alarm? Not to mention my 7 has power NOTHING (but thats a good thing because it weight 150lbs less than most other 7's) so all the alarm will do is shut off the ingition when armed and go off when you open the door. But anyway thanks for your help folks.

I kinda wish I had a GTUs. :(