Technical Alarm with a mind of its own !

[doeflax]

Hi again guys,
can anyone assist ?? I have a Multipla 2002 model and when I set the alarm on locking with the keyfob everything is fine for maybe 7 or 8 hours, then WHAM ! the alarm goes off for no apparant reason ! ( neighbours aint too impressed ! ) No attempt was made to enter the vehicle and the car wasn't bumped or nudged, and this seems to happen regularly. Anyone help ? ?

 

[JTDman]

This used to happen on a car i knew and all it turned out to be was the seat belt retracting after being pulled out and left , it was setting the internal sensors off at random times .

 

[widemouthfrog]

Is the battery on the way out? The alarm detects voltage drop as well as internal movement (I think).

Many years ago I had a Citroen BX that had a similar fault and that turned out to be a bulging plate in one of the battery cells causing the voltage to drop.

 

[ahhl]

it happened to mine due to temperature change, cold weather. found out the bonet/hood switch ( similar to the door switch) causing it. inseting the washer to to the switch ( widening the gap) solved the problem

 

[SGThirkell]

Hi, if you look at the flashing LED on the dash, once the alarm's gone off, it will flash a number of times and then stop, then flash a number of times etc etc. Count the flashes and it tells you what set it off.

1 flash = right front door
2 flashes = left front door
3 flashes = right rear door
4 flashes = left rear door
5 flashes = volumetric sensors on ceiling light
6 flashes = bonnet
7 flashes = boot lid
8 flashes = ignition power supply
9 flashes = power supply +Battery
10 flashes = at least 3 alarm situations.
Fixed light = transmitter battery low.

Hope that helps narrow it down.

 

[Zundapp]

And make sure all your windows and sunroofs are properly closed - if they're not, it sets off the volumetric sensor.

Or maybe you've got a mouse living in the car!

 

[chr1s]

it happened to mine due to temperature change, cold weather. found out the bonet/hood switch ( similar to the door switch) causing it. inseting the washer to to the switch ( widening the gap) solved the problem

Same problem and solution on mine. Alarm possibly triggered by vibrations from passing vehicles. I made a small 'extension' to go on the switch.
Still triggers very occasionally, but due to interior (volumetric) alarm not bonnet switch.

(Of course, at its last service, the mechanic saw this bit of rubber on the switch and removed it - so the alarm triggered that evening and I had to make another)