Help my car alarm is going off all over the place.

As in 150 mile drive park up 4 hours later off it goes, leave it at work all day 7.30 -4pm not a squeek, drive home park up 2 hours later off it goes. Reset alarm stays quiet till about 2am weird eh

my mechanic friend scanned the car and told me its coming up with 

1 Fault Found:
01134 - Alarm Horn (H12) 
            49-00 - No Communications

So reading through various forums websites it could be wiring or more likely culprit the alarm horn itself? some even stating the car battery as mine is less than 18mths old i will bypass that one.

But any other avenues to follow i will gladly carry out.

My initial response is to purchase a cheap (relatively) alarm horn strip it and replace the batteries and replace the old one at least then i know 2 out of 3 areas are sorted, But i am scratching my head for the fuse any help please ??

update for today alarm seems to be reducing in time duration before going off was about 4 hrs now down to about 1 hr neighbours arent happy but what can you do at 3 am in the morning lol 

Try turning off the motion alarm. It's a button on driver door on my Roomster. You have to lock the car immediately after pressing button.

If the Siren battery is gubbed / almost a dead parrot then remove the siren until you get on or get the battery replaced as you mean to.

 

Bryan  B cheers mate tried that but it didnt alter anything lol , and after waiting a little longer the alarm timings went  down to around every 30 minutes ! even went to work early so it could only be heard by birds.

Awaoffski thanks mate i got the siren out took 4 hours some twerp at the factory loctited the wiper arms down so nearly 3 hours to get them off as a wiper arm puller just about managed it after shocking the arm head with a hammer! Ive measured the voltage of the Varta battery inside and its 3.6v which i think is about right? will google some more. Thank you so much for your responses, and anything is appreciated. thanks so much

 

Hello BH12,

Mine did occasional random alarms a couple of years ago, usually in the early hours, parked outside and was able to grab keys, press unlock then relock on the remote, return to slumber.

Turns out the interior light switch near the rear-view mirror was iffy, if the light flickers on, the car must sense a brief tiny voltage drop, and guess it's programmed to activate the alarm if any doors get opened without using the key.

So the interior light coming on (albeit very briefly) was enough to trigger the alarm.

Sourced a used replacement light & switches assembly via the bay of fleas, fitted, all has been calm.......

HTH

Richard

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Help / advise needed please. Alarm goes off when it feels like. All doors windows boot bonnet closed.  No passing animals. 6am today it goes off 4 times in as many minutes. Enough’s enough! Has anyone with the same problem found the only permanent solution is to have a new alarm siren installed? Neighbour’s are tolerant but not at 6am!

I had a similar issue last year, it turned out to be a faulty microswitch in one of the door locks telling the car that a door was open when it wasn't.

It's easy to diagnose, just look through back window when the alarm is triggered and see if the door open light on the dash is on.