My car alarm keeps going off but I can't find out why, but when it's going off is really weird and suggests to me someone is doing something that's setting it off. This weekend it's been set off about 5 times, last time it went off before then was last bank holiday weekend and it's going off at simillar times as it did then. To add to the mysery, another vectra of simillar vintage has also had it's alarm set off both of these weekends.

Last time it went off three times in a row so I hid in a hedge but it didn't go off the whole hour I was out there. The interior alarm is switched off. Anyone got any ideas? I just think it's far too much of a coincidence for it not to be an external factor. Unfortunatly I can't test this by moving the car as the only free parking is right next to it or quite a way down the street.

My home wifi set off the alarm on my Mazda 6 until I changed the channel on my access point. It still goes off if I leave my phone in the car and it hunts for networks.

Regards,
Dave

I had a wireless slate [for teaching] which blocked just about everybody's remote locking on our street including mine, until we realised what was causing it.

I think it's likely to be something simillar to this, but that it only happens on Bank holiday weekends is the part thats really getting me, I can only assume someone has guests using something sending out a signal. Doesn't help that there is no way to deactivate the alarm.

If you are suggesting Wireless interference (NOT just WiFi), then you need to check what frequency your Alarm is working on.
Otherwise you will be chasing your tail for a good while!

The most widely used frequency is 433 Mhz, and its mostly older ones that use this frequency. Its also used by a host of other devices totally unconnected to alarms. eg garage door openers, door bells, etc etc.

The later ones are on 868Mhz, and these are newer.

There will be some on 2.4Ghz which is used by WiFi, and TV/Video Extenders (downstairs to upstairs type of devices).

Your Key Fob Should tell you what freq it is working on, or at least a Google search should identify the working frequency.
Once you have identified the working frequency, then you can start looking for an interferring source.
Until you know where to look, you will not get very far, as its pointless chasing every 2.4Ghz device in your area if your Car Alarm works on 433Mhz.

You could be a while tracking down an intermittent radio signal that is the source of your troubles.
You will be lucky if its a permanant signal, as this wold be easier to find.

I doubt if this will help, but at least you might be able to start looking in the right places first.

If the alarm is a voltage drop monitoring type a duff car battery can cause this -- the car battery voltage slowly drops when the engine is switched off, if the battery is duff the voltage drops too quickly triggering the alarm.

Badly adjusted pin switches on bonnets are a classic cause intermittent false alarms, especially when it's windy.

I don't think it's either of those as the battery is less than a month old and it's not been particularly windy, that and it happening to two vectras on the same street on two bank holiday weekends and not doing it any other time.

Anyone around got a caravan? We have a caravan with a caravan mover system (drives the wheels by remote control, so we can drive it out of tight storage spots and up to the car). It's radio controlled and when in use moving the van it sets off 4 or 5 local alarms, either due to its own clashing frequency or the pwm driven monster motors it uses,


Would explain the holiday link if they are clustered at either end of the holiday.

Ive not seen a caravan out there, but just as last time, no trouble now the weekend has finished. One of the times i could hear a whiring noise like a motor.

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Originally posted by morcus
Ive not seen a caravan out there, but just as last time, no trouble now the weekend has finished. One of the times i could hear a whiring noise like a motor.

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