Random Alarm chirps

In recent months my 360 Modena alarm has gone off a few times for no apparent reason. Two days ago it started giving off a single chirp at random intervals, driving my wife and one of my dogs nuts. The interval between single chirps is sometimes 10 minutes and sometimes 4 hours or more. The door locking, unlocking, arming indications are normal, but the single random chirps wouldn't stop. The red alarm light seems to be working normally and I'm not convinced it's an alarm battery failure, but I suppose it could be. It strikes me as something wrong with the alarm logic.

I disconnected the siren unit and when doing so it gave off a few additional chirps when I moved it as if something was lose inside. I have some questions before I open the case to have a look.

Is the alarm logic part of the siren module or is there a separate logic unit?

Is the motion detector inside the module or is it located somewhere else?

Has anyone else solved a random single chirp problem by replacing the siren module?

 

Very often the problem with these systems (from any car manufacturer) that causes this symptom ---- random chirps from the siren ---- is the internal / supplemental battery in the alarm module going dead.

These batteries are all of the re-chargeable type, but they all also go bad eventually ---- as does any re-chargeable battery as they all too have finite life spans.

If you do a search here on the site, you will find several threads with detailed how-to instructions and advice about how to replace the battery in your 360's alarm system.

 

That stoopid horn is just that. A horn. When you open it, there's a circuit board, a speaker and some rechargable batteries. When the batts go it can do funky things. Likely shorting out or the circuit board is shorting.l I'd put my money in the alarm module personally because they go with such frequency.

Alternatively, I'd be thinking a switch like hte hood or bonnet is monentarily contacting/closing... but if the car is completely unlocked, I'd wager the alarm siren.

Could it be random interference from other sources perhaps? Any new garage doors or electrical appliances? The alarm main logic board is pretty robust.. I'd think a siren before the main board.

 

Before I opened the original I though it must be simply a siren; however, I was surprised to see how many components were on the circuit board. So I'm guessing that there is some kind of logic going on in there, faulty thought it may be at the moment. That makes me think that taking a peek inside the new one might be worth while and I'll go for the external battery mod while I'm at it. That was my plan A last year before I discovered the circuit board on the first one was completely eaten away. Frankly I was somewhat taken aback when the dealer from whom I purchased the car mailed me a replacement siren at no charge.

After another cup of coffee, I'll get out the fine blade saw and crack the case on the newer one.

As for interference, I doubt it. I live in a remote area of northern Italy where although most of my friends have TVs not all of them do and only a handful of them have access to the Internet. RFI is way down on our list of worries.

 

FIXED............... I think, ............. or at least I hope. I sawed the case open and everything inside looked fresh and clean except that one of the pins was slightly bent. I straightened it out. The batteries produced 3.6v each, which is correct. So I sealed it back up.

When I connected it, I noticed that the plug didn't really seat properly. After some fiddling around with my dental picks and my Jewelers Head Headband Magnifier I realized that the unused pin wasn't engaging the plug properly. There are four pins but only three wires. I adjusted the pins slightly and cleaned up the sockets in the connector plug. After that the plug slid home easily and the locking catch engaged without difficulty.

I don't recall specifically releasing the plug locking catch when I disconnected it yesterday. When I originally installed this replacement siren I remember that I was concerned about fitting the plug without bending the pins. I also remember thinking that this is a pretty crappy plug design, so perhaps I never did have it seated correctly. Over time it became more intermittent.

Now it works as it should and, so far, no random chirps. I've got my fingers crossed.