I own a 1988 Convertible.....

So just last night I had the center console off to fix a small ground with my aftermarket stereo, and after I was done and went to lock the car, I noticed the alarm didn't arm or make the beep....

So tonight I got home and did some testing (after having browsed the forums a bit last night and looking at the FSM a bit). Here's what I can tell...

1) On both doors, if they are locked and I turn the key to just unlock the door, but don't return the key to the position to remove it from the cylinder, the light on the security panel illuminates. This happens in both the driver and passenger doors.

2) If I have either door locked, and then lock the other door, I get no light, nor do I get a beep.

3) I'm fairly certain the door switches work, because if they did not, the interior lights would not light when the doors are open. Correct?

This leaves me with the hood and the trunk...right? Assuming that nothing else is having issues, those are the only things it could be yet. Anyone have any ideas? (aside from just installing an aftermarket alarm system...I don't have the cash for one yet)

EDIT: I checked the trunk, and it exhibits the same thing as the doors. If you unlock it with the key, the security light illuminates as long as the key is turned.

 

When you lock a door, the system arms. If you go to lock the other door, the system is already armed, so it wouldn't have to arm itself again. To test the alarm, roll down the windows and lock the car, then open the door from the inside. Your car should be at about Defcon 16 right now, putting the key in the door and unlocking it should disarm the system. It's been a while since I've set mine off, but IIRC that's how you do it. If it's not the door, it's the ignition cylinder. Basically the stock alarm just flashes a light, and sometimes decides to go off in the parking lot of Kroger when you have a case of Mountain Dew in your hand.

 

Well, thats the thing. I've tried that. Roll the windows down, lock the car like I normally would, let it sit 5 minutes, and then unlock the car from the outside by reaching in through the window and using the door lock inside, and it does absolutely nothing, aside from unlocking the door.

No alarms go off, nothing happens. And this is from an alarm that was functioning fine just a few days ago, and as I stated in my previous post, I haven't changed anything except changing 2 grounds on my aftermarket stereo.

 

Ok, so both my door switches seem to be fine. The interior lights illuminate when I open either the passenger or driver door. The trunk lid also seems to be fine since when I open that, the interior lights come on as well. That leaves the hood latch....and a possible cold solder joint on the CPU board. Because I'm not too sure on how to check it, any possible quick way to check the hood latch to verify that is not the problem? I've seen it mentioned in other similar posts, but never any definitive "Do this and this" to check it.

 

Im gonna go with bad solder joints in the CPU, mine went out a few weeks ago, a day before inspection even, which i wouldnt have cared about but the bad solder joints affected other things the CPU controls as well like on my S5 vert.....the highbeams which wasnt very good with inspection coming up.

Check other things that the CPU would control ie. (seat belt chimes, key chimes, lights on chimes ect.) theres a possibility they might still work but might as well check i know icemark has a list on here that shows what the CPU controls for different series (s4/s5) and body style (coupe/vert) might want to look it up.

 

Is it just me, or is the 88 vert not exactly the same in the sense that the "Theft Deterrent System" is located on the passenger's side, and the CPU is located on the drivers side?

Could it possibly be the Theft Deterrent System that is causing this problem?

I'll probably take them both out and check them today just to be sure.

 

Awesome. Ends up it was the CPU solder joints. I took the CPU (3 boards) out, removed the solder using solder wick as best as I could, resoldered, and sure enough the alarm worked on the first try. Thanks guys!