Alarm Goes Off Every Morning!

[rayfry]

the alarm on my '95 2.1 td vsx has started to sound every morning when i start the engine. the car is opened in the usual way with the plip and the doors unlock as they should,so the alarm should be turned off.Am i right in thinking that the alarm senses low voltage? as the engine turns over.Ihave tried to turn off the siren with the under bonnet key switch but to no avail.Is it possible to disconnect? where is the siren? On subsequant starts throuout the day the siren does not sound.Help Please!!

[techmanagain]

Flat battery, or more likely on its way out. Get a new one before the really cold weather sets in.The siren is under the driver's side headlamp area.

[robertxmb]

It would appear the voltage drop on starting is sufficient to cause the alarm to reset and arm itself in the same way as disconnecting and reconnecting the battery would. As techmanagain says a dying battery is a likely cause. If you are lucky it might be a high resistance joint such as battery clamp or other poor alarm connection.
I had an XM on loan once that drove me nuts due to random spurious alarms. Tried activating the button beside the LED to disable the internal volumetric sensors leaving perimeter protection on doors only, no good. Then aha! I thought alarm is set by plip so dont use it, instead lock and deadlock the car using the key only as book said the alarm will not be set with the key. Some time later the alarm went off! How could it ? I cancelled the alarm, locked and deadlocked the car again with the key. No flashing LED so not armed. The next bit I would not have believed had I not seen it happen.Some time later I happened to be looking at the car when the indicator lamps lit for two seconds and went out. I approached the car and the LED was flashing every second; the damn car had self-set the alarm! In due course the alarm went off spuriously as before. I had several reruns to witness what was happening again and again before getting the alarm disconnected
While on the subject, I am curious to know if anyone here had a similar experience and if so did they discover the reason?
Also how many of you have perfectly operating alarms on your XMs?

Robert.

[rowanmoor]

My alarm works perfectly. Had to replace the interior sensors when I first got it to stop the false alarms, but once I did that I haven't had a problem since (except when my battery died and it went of when trying unsuccessfully to start the car).

[xmexclusive]

Hi All

There are a number of variations to the Mk2 XM alarms both by country and by age of car. One of the later UK variants looses the under bonnet alarm isolation switch and if on leaving the car the alarm is not set the ECU waits 1 hour and then sets the alarm on. In looking through the owners handbooks a while ago I think I found 3 different UK alarm versions for the Mk2 XM.

Regards

XMexc

[Ciaran]

I would concur with the low battery / bad connection theory. I've had problems with the alarm on the S2, and each and every time it has been down to a battery being on the way out, or a bad connection (had dodgy terminals on one battery).

The being unable to disable the siren, and the system sporadically arming itself / sounding without being enabled, are classic symptoms of this.

Dare I say it, the XM alarm is actually quite reliable as long as your battery is in good nick. I agree it doesn't half develop a mind of it's own when things are iffy. Though its good to know that the battery backup in the siren works (had that on a garage forecourt one night), and that the system will default to armed should power be lost.

Ciarán

This post has been edited by Ciaran on November 28, 2007 11:27 am

[DerekW]

Touching every bit of wood within reach, my alarm works perfectly as does everything else on my V6.

But it occasionally (three times in the past four years) completely flattens its battery overnight.

On the estate, all I have left of the alarm is the underbonnet key switch and a bunch of cut wires, so a previous owner must have had problems.

Derek

This post has been edited by DerekW on November 28, 2007 05:03 pm

[rayfry]

Thanks everyone! It looks as if its the battery at fault although it starts the car every morning and my inner skinflint says its OK I'll have to bite the bullet and get a new one! Thanks again