Alarm service required
 

My alarm goes off in the night and is now showing a service is needed. I can lock the car and leave for a while without it going off.
Where would I start to look for the fault please ?

alarm siren failiure its a common problem with some volvo models of a certain age .

Almost certainly the battery within the Alarm Unit.

Provided the printed circuit board is ok, a new battery can be fitted if your handy.

When mine played up , a replacement battery was of no use due to damage to the circuit board from the old battery leaking.

I bought a good used alarm unit which sorted it.

cheshired5 on here has done a video covering this.

+ YouTube Video

I agree, but would add that if simply replacing the battery, clean the board thoroughly to remove any residue.
I replaced mine as a precaution when I first got the car. There was minimal damage when I took it apart, but no symptoms yet.
Then, 2 years later I had problems. When I took it apart again, the corrosion had continued.
I had to carry out some major board repairs, but this time I washed the board with white vinegar, then clean water to kill off any battery residue.
Obviously, I dried it thoroughly before re-powering it.

More information on this thread.
https://www.volvoforums.org.uk/showthread.php?t=306010

Many 😊.
I’ll give it a go when the weather permits and I’ll let you know how I get on. :teeth_smile::teeth_smile::teeth_smile:

7.2v battery
 

Just bought the same battery shown in the video from eBay for £14. Should get it by the weekend 😊

I have removed the siren from the car and will split it open later today. The car still operates without it and does not show any fault. 😊
I have not locked the car.

Motherboard goosed
 

Part of the board is burned out.
Anyone got a spare please?

What does this module control please?
Can I get away with not replacing it?
I have not locked the car since removing it.
Will the doors still lock and unlock without it?
I’m not bothered about having an alarm. Just need to lock the car.

Hi, I had same problem on my XC90 and on previous V70. I tried replacing battery on my old V70 and although PCB seemed ok, did not fix the problem. I then replace the whole module and end of problem.

When I purchased my current XC90 it had this problem as known fault. I simply purchased a new unit and fitted that.

I do have my old unit of this latest car, I have not tried to open it, it is just as it was when I removed plus it has the spare security bolt (which I never replaced).

You can see second hand units on the 'bay for about £50 and new will cost about £180. But note they all fail after a time so second hand is risky.

The car will work fine without it but beware of the insurance implications. This may not bother you, but would concern your insurance provider. This was the only reason I wanted mine fixed, that and the BL**Dy message each time car started.

It takes about 1 hr to replace plus the new pop rivets etc. My view is just replace with new and forget about it.

You also very welcome to my old unit, but not messing about opening it up. You can have it for the cost of postage.... But I know battery has failed and so could the circuit board..

But again, the cheapest option time wise is just to replace the unit with new.

Cheers John l