Alarm - Goes Off In the Sun

[ThreePointFive]

So for a while I've been driving a 2002 TD5 ES and it's a lovely car, it does everything I need it to.

However, it's got a habit of setting the alarm off if it's left in the sun. I haven't been able to find any other posts by the search - on here or elsewhere so I'm wondering if anyone else has ever heard of it.

There's no much more to explain besides that, on a cloudy/dark day the alarm will never go off, however, it seems to always go off on a sunny/warm day.

Anyone know anything like this?

[missingsid]

Aren't some early car alarms based upon air pressure or air movement, therefore open sunroofs and closed vehicles in the sun suffer?

Marc.

[teabag]

Some one is thinking of bank vaults that use air pressure or the lack of it as one means of sensoring, but the disco uses ultrasonic movement detection nothing to do with pressure as it uses sound waves.

Any movement within the cab will trigger the alarm when set although they are not that sensitive in a disco, why not try setting your alarm with the key, this will isolate the ultrasonic movement detector.. If your issue then goes away u know that you have a faulty unit therefore requires replacing. There's two units believe in a D2.

[bear]

Try just locking with your key. This will not activate the interior sensor (used when leaving dogs inside etc) so that would rule it out.

Griff

[ThreePointFive]

All,

thanks for the replies - opening a window or sunroof actually prevents this from happening, I can see no reason why that should help it at all.

I'll try using the key instead, it's better than nothing.

[teabag]

It was well known that ultrasonic only movement detectors can go over sensitive and cause false alarms due to hot air turbulence and even by a leaf falling from a plant, that's why in the commercial security industry we don't use them any more even if they were still available, duel technology detectors are used now.

Anyway back with the disco, set the alarm with the key and unset with the fob, if no more problems then replace the detector/s as they are now over sensitive unfortunately they can't be adjusted... or just remove from the headlining and unplugged and refit back into the headlining.

[Simon_CSK]

just remove from the headlining and unplugged and refit back into the headlining.

This is what I have done because I have dogs in the back most of the time and there has never been an issue with the alarm.

[sierrafery]

The volumetric alarm if it became too sensitive can be disabled in BCU with tester too, not compulsory to unplug the sensors for that

[rrr47]

Check the air vents are shut and look out for flies/moths/spiders and the like in the cabin area. My alarm was playing up in sunshine, turned out to be a spider dropping/hanging down from the rear view mirror setting the alarm off.

[teabag]

Check the air vents are shut and look out for flies/moths/spiders and the like in the cabin area. My alarm was playing up in sunshine, turned out to be a spider dropping/hanging down from the rear view mirror setting the alarm off.

A faulty sensor then, replace it.