XJ8 alarm problem

[piefacemate]

Hi all,

My 2001 XJ8 Sovereign seems to have developed a bit of an annoying problem with it's alarm. After being parked up and locked for a period of time, usually 30 minutes or so, it's alarm will go off for a minute and then stop. The car afterwards is then fine.

I couldn't see any obvious reason why it'd do this, all the windows were fully up and all doors closed. Does anyone have any ideas what could cause it to do this?

Cheers,

Chris

[piefacemate]

TurricanII said:

battery voltage dropping? Do you get a couple of brief waring messages about traction control/abs when starting up too?

I've not noticed anything of the such, but then I've not been looking specifically for it! It flashes all the lights as it does it's start-up diagnostics and the airbag light stays on the longest... but other than that...

I'll make a point of checking next time starting it up.

Jaguar steve said:

It might be you have a faulty detector or could be nothing more than currents of air moving around inside the cabin or swift temperature changes triggering the ultrasonic movement detectors.

The sensivity of the detectors is adjustable using the Jaguar WDS. Dispite the sensivity being set to low mine still does trigger the alarm occasionally if locked remotely - particurlarly if the car is in hot sun then goes into shade.

If you physicaly lock the car using the key rather than the remote fob then the alarm is set without the movement detectors being armed. Try this for a while and see if that makes any difference

Thanks Steve, that does make some sense as I moved the car from a cool underground carpark above ground in direct sunlight when it first did it.

I don't know what the Jaguar WDS is, is it possible to adjust this myself or does a Jaguar specialist need to be involved? If it was a faulty sensor, again is this self-diagnosable / fixable?

Will try manually locking the car as a temporary measure.

[piefacemate]

Great diagnosis guys, and many thanks to all who responded.

Been using the key to lock the car for a week now and haven't had the alarm go off. Not really an ideal situation, having the alarm partially disabled to get around the problem, but is certainly preferable to upsetting all the neighbours!

To everyone who's investigated having this repaired: What's involved? Are we talking a replacement of the sensors or just adjustment of the sensitivity? Does anyone have an indication of costs?

Cheers,

Chris