Alarm Went Off!

[Poobah]

I've had my 2000 Deville for 6 months, now, and this has never happened before:

I went to lunch, parked the car, and locked the doors using the push button on the driver's door just like I always do. When I came out of the restaurant, I unlocked the driver's door with the same key I always use. When I opened the door, the horn started honking and the lights started flashing. I was startled and didn't know what to do. I got in the car, closed the door, and still didn't know what to do. When I put the key in the ignition and started the car, the horn stopped honking, the lights stopped flashing, and the DIC said "THEFT ATTEMPTED"

The next time I stopped the car, I read about the theft deterrant system in my owner's manual. It said it would be set off if an unknown key was uset to open the door. The key I used was the same one I always use. Did it suddenly become "unknown" while I was at lunch?

I've locked and unlocked the doors a half dozen times since then and the alarm hasn't gone off again. I'd like to know what happened and how to avoid it in the future. If nothing else, it was embarassing!

[JimD]

Smoke and mirrors.

Unpredictable events occur at random times with the systems in modern cars. If you can't make it repeat, I would not be concerned.

If it does repeat in the near future, it would be worth pulling the codes to get an idea where to start looking.

[Breeza_Brown]

maybe some one attempted something while you were away.... IDK.

[Cadillac Jim]

In my 1997, if I lock it with the fob or the inside electric door locks, the alarm will go off if the door is unlocked using the mechanical (not electrical) door lock and the door is opened. The salesman told me about that when I bought the car, and my wife has actuated that one two or three times over the years when I left her in the car for a quick errand. That basically means instant alarm when someone tries a slim jim door-opener. By law, audible alarms must silence after seven minutes. That's probably what happened with your car while you were at lunch. When you got back, the door was already unlocked and you didn't notice.

I think maybe Brezza Brown got it right.

[Poobah]

Well, it happened again! Three days after the first occurance, the alarm went off again. This time, I got right into the car, put the key in the ignition and turned it to on (not start) and the honking horn/flashing lights stopped.

I always do exactly the same procedure. Park the car, get out, lock the doors with the push-button on the driver's door, close the door. When I come back, I unlock the driver's door (always with the same key) and and open it. Usually, everything is OK, but twice in the past three days the alarm has gone off.

Both times, when the alarm went off, no codes were set. I think the repeat performance makes it very unlikely that it's either a unique, random, and unpredictable glitch in the system, or that some would-be theif just wants my car.

I think it's far more likely that an intermittant problem has developed in the alarm system. I looked it up in my factory service manual and the first thing it says to do is hook up a Tech 2 (which I don't have). There is also discussion of how to get the car to relearn your keys.

At this point, I'm just baffled by it. Hopefully, somebody out there can point me in the right direction.

Thanks in advance.

[Cadillac Jim]

There is a switch in the key lock that turns on the headlights and possibly unlocks the rest of the doors, depending on customization, much as the unlock function on the fob will do. If it isn't operating, the security system will operate as if the door had been opened by a slim jim. I think that this switch, or its wiring, may be intermittent.

[Logan]

Dont think I have used a key to unlock a car in 10 years.

Are you using the key, or the remote to unlock the car? Big difference..

I dont see any bulletins.