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C30 / S40 & V50 '04-'12 / C70 '06-'13 General Forum for the P1-platform C30 / S40 / V50 / C70 models |
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Alarm keeps soundingViews : 1098 Replies : 11Users Viewing This Thread : |
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Sep 9th, 2019, 16:39 | #1 |
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Last Online: Jul 26th, 2023 19:57
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Alarm keeps sounding
Hi
I have a 2011 C70. When I got back to the car yesterday there was an error message saying to check the car as the alarm had sounded (or words to that effect). Then today, the alarm went off for no apparent reason I'm concerned it may go off in the middle of the night and disturb the neighbours. Any ideas what I should be checking as I don't really know where to start looking Thanks, Graham |
Sep 9th, 2019, 17:26 | #2 |
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2008 C70 D5 SE Lux Nav Geartronic |
Sep 9th, 2019, 20:47 | #3 |
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Last Online: Jul 26th, 2023 19:57
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Thanks for the link. That thread is about the alarm going off as soon as it is switched on.
Mine doesn't go off immediately, I am guessing/hoping maybe its a spider or something. Is that possible? |
Sep 9th, 2019, 21:23 | #4 |
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It's fairly likely that the battery in the siren unit is shot. I had that on both the S40 and V50 so bought a newer second hand siren unit and swapped them over which solved the problem. Given your car is a 2011 model you'll struggle to do that so you can either split the siren unit open and change the battery yourself if you're moderately handy with DIY and electrics (there is a thread on the forum somewhere about this) or get a new siren unit from Volvo.
On a V50/S40 it's located in the plenum chamber under the windscreen at the rear of the engine bay, normally on the passenger side.
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Sep 10th, 2019, 13:29 | #5 |
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My money is on the movement sensor located in the middle of the headlining, this often fails and just sets off the alarm for no apparent reason. Connecting to Vida will tell you what sensor set off the alarm for at least the last 10 occasions.
A temporary solution is unclip the sensor and disconnect the wiring, you will get an "alarm fault" on the dash every time you start the car but just clear it, hopefully the alarm will no longer randomly sound. I bought one off ebay for £15 and it works OK. If the alarm still sounds with the movement sensor disconnected I'm afraid it is another fault, best of luck. John
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This is a Bike friendly Volvo-N.A.B.D. member 2000 V70R AWD - SWMBO 2017 XC60 D5 AWD --- Previous - 2009 V50 D5 SE LUX - 2000 V40 SE 2.0 - 1986 760 GLE 2.8 |
Sep 10th, 2019, 19:49 | #6 |
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Sometimes it would take a while before the alarm would go off, usually in the early hours The siren module internal battery has a life of 8 to 10 years, when it expires it gives the symptoms described. As per that link I posted I replaced the siren module about 18 months ago & it's been fine since.
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2008 C70 D5 SE Lux Nav Geartronic |
Sep 10th, 2019, 21:36 | #7 |
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Thanks again for the input.
Last night I took my chances and left the car unlocked so there was no risk it would disturb the neighbours. Then I locked it this morning and it didnt go off all day. Have unlocked it again for tonight. So have only had two false alarms so far Following on from what John has said - I have a generic diagnostics machine, would that show the reason for the alarm sounding do you think? I have tried to find a source for a new unit, but cant seem to find anything online (other than used one's on ebay that might also have battery problems I guess) - Would anyone know a good company to try? Many thanks |
Sep 12th, 2019, 16:37 | #8 |
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A generic code reader usually only reads engine faults where as Vida reads everything including alarm faults and it records alarm events and what sensor caused it. Disconnecting the Mass Movement sensor does not disable the alarm it just won't pick up movement in the car. When ours started playing up the alarm just randomly went off usually in the middle of the night.
John
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This is a Bike friendly Volvo-N.A.B.D. member 2000 V70R AWD - SWMBO 2017 XC60 D5 AWD --- Previous - 2009 V50 D5 SE LUX - 2000 V40 SE 2.0 - 1986 760 GLE 2.8 |
Apr 1st, 2020, 18:01 | #9 |
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Hello. Where did you find the siren module on your C70? I think I have the same problem. Thanks!
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