I have recently purchased a 1997 V40SE 2.0 which appears to have a fault in the alarm system. The alarm will go off all by itself, but only when it is parked on my drive and only between the hours of 2am and 6:30am. It does not go off during the daytime or if parked elsewhere (though I haven't done that enough to be proof).

I first thought it was due to the sunrise changing the temperature in the car suddenly, but when it started going off at 2am I knew that couldn't be the answer.

Having to leave the car unlocked is not really an option I want to continue. []

Any thoughts?

 

One possibility that comes to mind might be a bad door lock motor.In the over night hours when there is more moisture in the air causing the switch to malfunction.I dont know very much about the 1997-1999 modules because they were not avalible in the U.S. untill model year 2000.Another possiblilty may also be a bad remote if your remote has the panic function on it.If it does make sure the panic button on the remote doesnt feel like it pushes easier than the other ones.If it does try taking the battery out over night and see if that helps.

 

The problem appears to have stopped all by itself. A few explanations were given but I've not been able to prove any of them. They were:

Neighbours cat which loved sliding down the rear of my Rover 800 fastback has now aquired a distinct interest in the Volvo from the paw print that I find on the roof.
Leaving the remote key fob next to my mobile phone, for which the network activity and resultant signal strength changes during the quiet period of 2am to 6am.
Alarm fob batteries getting depleted as I can't unlock the car from much more than arms length away. I do have long arms though. [:-]

 

damn cats[:'(][:'(]

 

I had same problem I was told it was the alarm sensor under bonnet , I just dont use remote alarm key , i just lock with key, saves hassle of waking neihbours...