Alarm goes off when frosty

Moloko

Member
Can anyone pleeeeease help me as this is starting to get very annoying!
My A2 (Y reg diesel 1.4) alarm goes off when the temperature outside reaches freezing. I don't know if this is coincidence or cause, but since winter came it has only gone off when it has been frosty and not gone off when it hasn't.
I've checked all doors, boot & service flat are closed. I've taken it to a dealership, but it wasn't frosty while it was there and the alarm didn't go off so they couldn't get the fault code. They checked all the connections for the doors, boot and service flap and said they were all fine.
I'm having to disconnect the battery every night as the 'alarm off' button isn't playing and the little beast sits outside my bedroom window beeping all night long and won't stop till the temperature goes up.
Any clues what could be causing it before i go mad? :confused:
 
Hi Moloko, Welcome to the A2oc
Do you get any other symptoms which would indicate the battery in the boot is on its last legs as this combined with the low night temps could trigger the alarm.
Other possibilities - The alarm on my car used to occasionally give 4 beeps immediately after starting and sometimes the alarm would go off for no reason. It turned out to be the alarm siren. This has an integral back-up battery which looses its capacity for holding a charge with age and causes the alarm problems.
Secondly, it could be a faulty module which controls the alarm and central locking etc but ususally this gives more than one problem.

Cheers Spike
 
The dealership thought it could be a low battery but as it didn't go off the week it was there they couldn't say for sure. It was serviced & MOT'd the other week and I got a brand new battery put in while that was done. It was fine untill it got frosty again.
I had it sitting outside my office yesterday as it was freezing outside and it went off at least 50 time in 4 hours. I tried leaving the service flap open to see if it was that triggering it and it went off every 4 minutes! So promptly closed it.
This morning when re-connecting the battery the alarm and central locking went crazy and it was going off when the engine was running! I turned it off and got out and locked it then the central locking was locking and unlocking really rapidly (I was locked out for about 5 mins with the keys in my hand and the alarm going off).
The back up battery for the alarm sounds most likely.
 
Unfortunately it sounds more like a faulty central control unit for the comfort system than the alarm siren. This handles the central locking and interior light as well as the alarm. I think the unit (located under the front passenger foowell) is about £220 plus fitting, which is relatively easy)

Cheers Spike
 
spike said:
Unfortunately it sounds more like a faulty central control unit for the comfort system than the alarm siren. This handles the central locking and interior light as well as the alarm. I think the unit (located under the front passenger foowell) is about £220 plus fitting, which is relatively easy)

Cheers Spike

Just had my control unit replaced today,luckily under warranty, car is :) again now....its not like a discoteque driving down the road. :D
 
Thanks guys. I think I'll just diconnect the battery over christmas and take it to a garage in the new year to have a diagnostics put on it - likelyhood of getting it in before is minimal, and i don't wanna go buying parts if it could be either alarm OR central control unit.:rolleyes:
I'll let you know how I get on when its done.
Merry Christmas to you all!

Moloko
 
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