alarm goes off at 4am!

[Rob.D]

Originally Posted by Lukasz Klimczewski

I had the same issue. It's one of door locks. Search for faulty door lock...
Don't try to clean it it will come back fter a while. Safe your self time nd buy new one ( second hand from ebay around 20-30£)

Once micro switch inside door lock get dirty it might gives false signal about opened door to ecu and light inside car turns on! While doors are phisicly locked .

Hi,
I've read all of the posts here with great interest. To cut a long story short, 2 new locks later at full retail for Main Stealer - Ouch! and in cold weather, my damned alarm still goes off at all hours!!! I'm told it's frost forming on the sensors! How the hell do I get round that one??? I sleep with the keys beside my bed. If I just lock it with the key, then of course the alarm is not set, and my Insurance is then invalid! Urrrrgh!
I know about the metal objects (no matter how small) in storage compartment, problem - so don't any more, yet still it goes off! Had fault codes cleared, you name it.... Oh! also had new alarm siren/backup battery unit replaced - NO difference.

Result: Well p'd-off Rob.

[meyrickt]

Look at
http://www.volvoforums.org.uk/showthread.php?t=79998

It worked for me

[crankie]

my 240 use to do the same thing it was caused by the rising sun shining on the ultrasonic sensors it had a sparkrite alarm not volvo

[Rob.D]

Originally Posted by meyrickt

Look at
http://www.volvoforums.org.uk/showthread.php?t=79998

It worked for me

Hi,
Thanks for that, but I've had a good look at the 4 sensors with a magnifying glass, and they all look absolutely fine.
So I'm still left with the idea that frost forms on the (door lock?) sensors (or perhaps some other sensors?) in cold weather. And sure as eggs is eggs, the alarm goes off! Someone said something about the air pressure dropping at night causing the problem? But that was before I replaced the two door locks. Perhaps I should get the other two tested, and if they can't make a circuit, replace them too?!!! ( Hmmmm, but then if that were true, I wouldn't be able to set the alarm, which I can...) Oh I don't know!

Frustrated Rob.