V70 alarm going off

[ASt85]

Originally Posted by ronmanager

Yes outside my house but only at night. Car has been parked there for years with no issue. If I stop the alarm with the remote and lock again it goes off again within minutes.

If I go out and start the car and lock it it can be an hour before it happens again. Locking manually with key in the door the alarm is off and no more alarms.

If it was sensors etc etc it would go off during the day too is my reasoning. What is definitely affected by cold weather? = the battery and like I said, I had an incident where the battery was running the car for 45 minutes with no alternator before all this started so may have damaged the battery - worst comes to the worst I have a spare battery. Currently I cannot take the battery out and charge it because to do so would require leaving the car open as I couldn't lock with no power - I do not have a driveway to charge the battery in the car.

It could be a neighbour's bluetooth front door bell, computer phone link or even more likely a wireless mouse triggering the alarm.

If doesn't happen anywhere else other than on your drive, the problem isn't the alarm it is extraneous input from something local to your drive........several mornings a week our house door bell is triggered by a parent unlocking their car having dropped off their child at the local primary......the culprit is a 2009 XC90 user!!!

[ronmanager]

The car is outside the house day and night and has never been triggered during the day as yet.

Anyway, a brand new Bosch S5 019 battery has arrived so we'll see.

[DOUGIE68]

Mine has done it I cold weather for years. Locking with the key is fine. Itll be fine when the warmer weather comes.

[fastdave2]

I had a 2008 XC70 that did the same, now my 2006 V70 has developed the same fault. On both cars the car battery eventually went flat I presume because the alarm module was shorting out. There's no way to avoid replacing the module or the module battery ( a doorbell battery will do) one way or another. In the meantime disconnecting the module will prevent battery drain and keep you motoring, but the alarm service required will always be on.

[ronmanager]

New siren and bonnet switch didn't fix it. New car battery didn't fix it. I now have a new (used) alarm sensor module to replace the one in the roof lining.

Does anyone know if these are plug and play and can just be swapped out with battery disconnected? The part numbers etc are identical.

[ASt85]

IMHO, if you are changing an electrical module ALWAYS disconnect the battery before you do the swap, followed by the recommended reconnect sequence.......saves so many problems down the first start thereafter line

[barrybritcher]

the roof thing is literally just a tilt sensor and you can run the car without it no problems as it wasn't in the poverty spec cars

[pierremcalpine]

I'm getting same symptoms - only happened a handful of times over the last few months and was too lazy to check VIDA for root cause (figured it was the alarm module given year (2002) and mileage (275,000km). I switched out the alarm module for a wreckyard version...no dice...it was a dud.

I then opened up my original alarm expecting the worst but the circuit board was pristine. Buuuuut, the connection between one of the battery wires and the battery itself was very flimsy to the point were all I did was touch it and it crumbled. So, it's very possible that the connection was occasionally resulting in the alarm being triggered.

Went on ebay, found an alarm on eBay UK for $30USD from xcelplustore and the battery was plug and play with the module.

It's now been a few weeks post-install and all seems fine.

[ronmanager]

Update. I changed the module in the roof lining with a used one off EBay. Last night was down to -5°C and no alarm!

Easiest fix ever and cheap to just try it - there's loads of them on Ebay for around a tenner.

Disconnect battery, pull down one in roof lining, unplug one connector, attach new module, push back in, reconnect battery.

Even if it doesn't fix it, it's the quickest one to rule out at least.

Part no. 30710517

[Critical Bill]

I have same problem with alarm going off for no reason.
I replaced siren module few months ago with no luck
Battery and circuit board in old siren was in good condition for 14 y/o car.

Anyway few times in the last few weeks I got message " Tailgate Open " from time to time especially on bumpy road or pot hole.
After searching web I found few posts pointing to micro switch in the tailgate latch .I checked this miro switch and is working.
the other think what people points out is broken wire harnes next to the hinge on LHS behind plastic covet/tab.
Not sure if this can help but may be worth checking

https://www.matthewsvolvosite.com/fo...ic.php?t=63428

https://forums.swedespeed.com/showth...e-all-the-time

https://www.matthewsvolvosite.com/fo...=47882#p236573