Alarm

[ibnct]

On several occasions now, during exceptionally heavy rain (little or no wind) my car alarm has gone off whilst sitting on the drive. As this has been in the middle of the night, I'm sure my neighbours are getting cheesed off and are now less than impressed with my latest purchase.
The alarm is silenced by pressing the unlock button on the fob. I tried pressing the lock button just once, instead of the usual twice but still the alarm was activated by heavy rain. To ensure a peaceful night, I have to unlock the car
I thought it may be due to blocked drain holes so tried playing the garden hose over the car paying particular attention to the area just in front of the windscreen whilst the car was locked. I couldn't set the alarm off, and the water appeared to drain away OK.
Has anyone else experienced this and are there any suggestions as to the cause and how I can stop it - short of putting the car in the garage. (not an option I'm afraid).
Nick

[mike020150]

Hi Nick, It's possible that your car alarm has a dodgy earth connection somewhere. So, in damp conditions the alarm may sense a consequent change in battery voltage which the alarm then interprets as an intrusion. Hence, I'd try cleaning all the underbonnet and other vulnerable earth points and coating them with vaseline. Alternatively, the only methodical way of getting to the bottom of XK8 electrical gremlins is with diagnostic equipment like that produced by Autologic and used by many Jaguar specialists or JDS at a Jaguar agent. Mike.

[Bassman]

Actually I think this is the rain hitting the windows and making them vibrate, making the interior sensor think someone has broken in


My XK has been on long ferry crossings many times in all sorts of rough seas without the alarm going off, the only times it has triggered is outside the house ( here and in France it's not fussy ) in REALLY heavy rain

[ibnct]

Thanks for your response Mike. I'm now of the opinion that it's not damp related because recently a sudden heavy hailstone shower set the alarm off before the car even had a chance to get wet. It's like the sheer force of the shower is the cause. - Does anyone know if there is a way of de-sensitising the alarm?
Incidentally, the alarm has not been activated under high wind conditions.

[DaveEssex]

Reference a similar experience, where I became just as frustrated as you appear to be, when my alarm would activate without apparent cause. I naturally assumed that the passenger cabin was the issue.
Not so - like many others I did not consider other possibilities, which it turned out was/is the cause of virtually all such concerns:-

Check the sensor on the hood-top or bonnet whichever you call it. These often deteriorate though exposure to moisture from frost/rain etc.

They are extremely cheap and easy to replace.