HELP: Problem with alarm [1999 S70]

A month ago I bought a Dec 1998 S70 [ 1999 model ]. The car sleeps in
my garage, under the bedroom window (imagine how I woke up). The car
has motion sensors in the pillars. One night the alarm went off
(LOUD siren) with no apparent reason. All doors, hood, trunk, sun
roof were closed/locked. There was no wind. Temperature, near 0
Celsius. It triggered a few times with from 2 minutes to half an
hour intervals.

Last night the same thing happed. All the doors/... closed/locked,
no wind, temperature aprox 7 degrees celsius. I have a motion
detector in the garage witch triggers the garage light for 3
minutes. I arrived near the car in say 30 seconds and the light was
off so I don't think that anyone was messing around (as soon as I
put my hand in the garage the light turned on).

This last time I saw that while the alarm was on the LED was
blinking in a very high rate (like 4, 5 times per second) Does this
mean anything? Does this alarm have any LED codes (like n blinks
means door entrance, x blinks inside motion, etc????)

As you imagine this is getting me mad! It only happened twice, all
doors rigorously inspected, none open, all during the night, never
during the day in an open garage (no doors do the garden wich is
locked from the driveway.

HELP ME trying to detect the fault, please.

Many thanks in advance,
Joao Caldeira

I had this problem with my '99 V70.
The alarm LED blinks rapidly when the alarm is triggered, quite normal.
This random alarm activation drove me (and probably the neighbours as well) to complete distraction and there was no logic to what was happening.
The problem stopped completely when the moth which was living in my car died ........... honest!
Try putting a burst of fly-killer spray in the car and leave it overnight to do its stuff.

Hope this works for you

Nick

Hi Nick.

I've posted the same question in the Yahoo! Groups Volvo Owners and the best answears are coming from a Nick, also (Nicholas,
Chepstow UK wales). You aren't the same, are you?

Well... at least I'm not alone!!! What was the frequency of "false" alarms in your case? It happened twice in one month with me, so I feel that maybe I don't have the same cause of yours... but I'll try the same...

Thanks,
Joao Caldeira

No I'm not the same person.
Frequency of mine was very erratic, sometimes daily, sometimes every few days, sometimes once a week, which made it all the more difficult to track down. All I can say is that one day I found a dead moth under the passenger seat on the fortnightly vacuum, and realised it hadn't gone off for a few days. It's never happened since.

Hi Nick.

I hope I have the same problem of yours... it would mean no costs...

But I'm unsure because of the fact that there was no LED blinking after I shut the alarm down. (If there was a moth or any other " friendly pet" it would trigger the pillars sensors, which would leave the LED blinking and would oblige me to move the ignition to position II to stop the LED blink - clear ??? might not...)

Thanks for your hope :)
Joao Caldeira