Electrics: New battery...... alarm siren

[Kevin_L]

Hi 2005 V70

Maybe a silly question.....

My battery has been on the way out for a while....had to definitely get a new one...got a genuine one....all perfect

Now....for a while my alarm siren has been sounding randomly when the car is armed, even with the dog button pressed....so I was having to lock with the key....the siren was new 5 years ago... genuine part.....I changed when I bought the car as i the owner said the alarm was messing around .....and the sunroof didn't work....and if I'm correct some of the power for the roof goes through alarm/same circuit....any new siren fixed the roof

Now.....back to today.... battery going flat.... alarm sounding randomly.....

I bought a new battery (£120) and was told siren is now a whopping £215....so I didn't get one

However.....I've been arming the car with the remote, and so far the alarm hasn't gone off randomly once since fitting new battery....

Related?? I thought sirens had internal batteries that packed up sheet a few years and that was that

Any ideas?

[VOLVOBOY]

Does sound as if the battery was drain being detected and triggering the alarm.
The alarm could be u/s so why not deliberately trigger it ? You`d know for sure if it were good or not then.
I think the replacement alarm modules are less likely to suffer from leaky batteries unlike the original .

[XC70Bob]

Another thing to check if you are getting random alarm triggers are to connections to the alarm loops on the rear side windows,



They are like a press stud so they should be a tight fit , I found some of mine were loose and that was causing intermittent alarm triggers, if you remover them you can carefully adjust the end that's on the wire with some needle nose pliers to make them a better/tighter fit,

[Kevin_L]

Hi

Thanks for that

As it goes the battery that needed to be replaced was a genuine one, but if had it for a while, it used to be in an 850 I had, I took it out and it was sitting in the garage for a couple of years before being reused

So, try to deliberately trigger the alarm....give the car a kick??!!

[VOLVOBOY]

No! . You can lock the car with a window open , wait for the alarm / immobilizer to set and then put your arm through the open window to trigger the system .
Works if it`s not too windy out .
Or , sit in the car , lock a set the system and sit still whilst it sets . When you move it should trigger the system .
Either way using the remote fob button.

[Jas16]

The alarm is linked with the sunroof via the UEM. So if the alarm siren doesn't work, so doesn't your sunroof. The module, I believe is behind the rear view mirror. I have a Topdon, but maybe better with VIDA, you can recalibrate the alarm siren.

This only works if there are no DTC codes present.

[Kevin_L]

Hi

So working roof means working alarm

I've not got to testing it yet, will do that at the weekend, but it's been sitting there for a couple of days as usual, but now armed, and the siren hasn't sounded once

It sits there up to a week not being used so the new battery is with the money

The old battery was so bad it was even difficult to jump start it

Ps, I live next door to a tube station, and a train station and bus stops....so the car sometimes doesn't get much use but even at 20 years old is ULEZ compliant so why change it

I even still put Volvo parts on it....and it's only done 194,000!!

[Darlo 1]

Originally Posted by Jas16

The alarm is linked with the sunroof via the UEM. So if the alarm siren doesn't work, so doesn't your sunroof. The module, I believe is behind the rear view mirror. I have a Topdon, but maybe better with VIDA, you can recalibrate the alarm siren.

This only works if there are no DTC codes present.

When my alarm siren was dead with a corroded pcb due to leaking batteries my sunroof still worked.