V70 Alarm Woes.

GSS · Oct 19th, 2023, 08:49

The alarm on my 2003 V70 2.4 diesel has started to activate for no obvious reason. I initially thought it might have been down to the motion sensor due to the high winds recently so set it to reduced guard, but it still kept going off. If I unlock it the alarm stops, (naturally), and the warning light on top of the dashboard flashes rapidly. When I lock it again, or the car relocks itself if I leave, it it may sit there happily for some hours before the alarm goes off again or it may reactivate within a few minutes. There is no set pattern. Has anyone any idea why this is happening or what I can do to prevent it, apart from disconnecting the alarm which is one piece of advice I have had.

VOLVOBOY · Oct 19th, 2023, 09:05

The internal battery of the alarm module is failing . What usually happens is that the acid leaks from the battery onto the pcb and ruins it . If you are quick to react when this first starts to happen you can sometimes save the module by cutting it open and replacing the battery . More often than not the thing is beyond repair and a new module is required .
You might as well try this if you are thinking of disconnecting anyway .

GSS · Oct 19th, 2023, 20:40

Thanks very much for that Volvoboy. Have you any idea where the module is located? To be honest, this isn't the first time it's done this. A couple of months ago it did it over a period of three days, then started to behave itself again. The odd thing is it only seems to happen later in the day or at night. It doesn't seem to make any difference as to where the car is parked.

Simmy · Oct 19th, 2023, 20:56

the alarm siren is located in the drivers side wing acessed by removing the arch liner. to acess the internal battery.you will need to cut open the unit. iv opened dozens of these sirens to try to find one with a good circuit board which took me a long time the one that was sucessful was from a late model xc 90 which had a different type of battery that had not leaked any acid on to the board . i then replaced the batterys you can still drive with the siren off the car the alarm will just beep the horn if disturbed.

Phil Croxley · Oct 20th, 2023, 07:55

Also worth mentioning that my V70 alarm was triggered by a micro switch in one of the rear doors, it took a Volvo diagnostic to find the problem, that's after I'd removed the siren and cut it open!

GSS · Oct 20th, 2023, 12:56

Thank you gentlemen for your replies.

Sotosound · Oct 20th, 2023, 15:21

Quote:

Originally Posted by Phil Croxley

Also worth mentioning that my V70 alarm was triggered by a micro switch in one of the rear doors, it took a Volvo diagnostic to find the problem, that's after I'd removed the siren and cut it open!

This happened with my P1 V70, and it had the nasty habit of waking the neighbours on frosty nights. A faulty micro-switch caused an unexpected voltage change. This caused the alarm to think that someone had opened a door and it got very alarmed about it.

Simmy · Oct 20th, 2023, 17:15

Quote:

Originally Posted by Phil Croxley

Also worth mentioning that my V70 alarm was triggered by a micro switch in one of the rear doors, it took a Volvo diagnostic to find the problem, that's after I'd removed the siren and cut it open!

im fairly sure on a 2003 it may be on its second alarm siren . battery life is about 6years . did you replace your battery as a matter of course after cutting yours open anyway?

concrete · Oct 21st, 2023, 12:09

Just pulled the fuse on my 2004 XC70.

Oct 19th, 2023, 08:49	#1
GSS Junior Member Last Online: Yesterday 12:47 Join Date: Sep 2007 Location: Now further south and west	V70 Alarm Woes. The alarm on my 2003 V70 2.4 diesel has started to activate for no obvious reason. I initially thought it might have been down to the motion sensor due to the high winds recently so set it to reduced guard, but it still kept going off. If I unlock it the alarm stops, (naturally), and the warning light on top of the dashboard flashes rapidly. When I lock it again, or the car relocks itself if I leave, it it may sit there happily for some hours before the alarm goes off again or it may reactivate within a few minutes. There is no set pattern. Has anyone any idea why this is happening or what I can do to prevent it, apart from disconnecting the alarm which is one piece of advice I have had.

Oct 19th, 2023, 09:05	#2
VOLVOBOY Lazy Member Last Online: Today 08:38 Join Date: Mar 2007 Location: HORLEY	Hi The internal battery of the alarm module is failing . What usually happens is that the acid leaks from the battery onto the pcb and ruins it . If you are quick to react when this first starts to happen you can sometimes save the module by cutting it open and replacing the battery . More often than not the thing is beyond repair and a new module is required . You might as well try this if you are thinking of disconnecting anyway .

Oct 19th, 2023, 20:56	#4
Simmy Premier Member Last Online: Yesterday 22:28 Join Date: Mar 2017 Location: Manchester	the alarm siren is located in the drivers side wing acessed by removing the arch liner. to acess the internal battery.you will need to cut open the unit. iv opened dozens of these sirens to try to find one with a good circuit board which took me a long time the one that was sucessful was from a late model xc 90 which had a different type of battery that had not leaked any acid on to the board . i then replaced the batterys you can still drive with the siren off the car the alarm will just beep the horn if disturbed. Last edited by Simmy; Oct 19th, 2023 at 20:59.

Oct 20th, 2023, 07:55	#5
Phil Croxley Senior Member Last Online: Yesterday 08:10 Join Date: Aug 2015 Location: Worthing	Also worth mentioning that my V70 alarm was triggered by a micro switch in one of the rear doors, it took a Volvo diagnostic to find the problem, that's after I'd removed the siren and cut it open! __________________ 2011 XC60 SE Lux premium

Oct 19th, 2023, 20:40	#3
GSS Junior Member Last Online: Yesterday 12:47 Join Date: Sep 2007 Location: Now further south and west	Thanks very much for that Volvoboy. Have you any idea where the module is located? To be honest, this isn't the first time it's done this. A couple of months ago it did it over a period of three days, then started to behave itself again. The odd thing is it only seems to happen later in the day or at night. It doesn't seem to make any difference as to where the car is parked.

Oct 20th, 2023, 12:56	#6
GSS Junior Member Last Online: Yesterday 12:47 Join Date: Sep 2007 Location: Now further south and west	Thank you gentlemen for your replies.

Oct 21st, 2023, 12:09	#9
concrete Member Last Online: Feb 27th, 2024 21:27 Join Date: Jan 2016 Location: Colchester	Just pulled the fuse on my 2004 XC70.

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