Bizarre alarm problem

[sparkythecat]

Car has been parked in the garage for 2 weeks, unlocked and without the alarm set.
A couple of days ago, the alarm went off and only stopped when I locked the car using the fob. Now every time I unlock the car using the fob, the fecking thing activates at its ear shattering loudest. It only stops when I lock the car again.

Any pointers or suggestions would be appreciated.

[bobfather]

I can only speak for the later cars with Meta systems. They are immobilisers too. The immobiliser arms automatically a few seconds after engine stop and does not require the car to be locked. I realise that's not an answer but it may indicate why the system alarm activated without the doors being locked

[s p a c e m a n]

Might be the battery on its way out in the siren, unplug it and see if it does it again.

[sparkythecat]

Not having had time to sort this out, I was content with the fact that when it was locked and the alarm set, it wasn't going off, even though though this meant I couldn't drive it until it was fixed.
However, at silly o'clock this morning, the alarm went off again and no amount of pressing the fob would stop it. The fob was locking and unlocking the car, and the siren was changing tone on each press, as though switching from main battery to back up battery.
After five minutes of frantically and unsuccessfully trying to spanner the vehicle battery terminals loose in the footwell, whilst in a fit of blasphemous rage and wearing only my underpants, the bloody thing inexplicably stopped!

So presently, I don't know whether it's armed or disarmed and when it's likely to go off again. I need to wait until later in the morning before I start pressing buttons again. In the mean time, I needed to find out more about the alarm system, which in 14 years of ownership has presented no problem to date.

The vehicle handbook is no use as the alarm instructions in there refer to a fob with multiple buttons and mine has only one.
So how do I find out what sort of alarm system I've got? Where the control unit is buried and where can I get help fault finding?

[sparkythecat]

It's just gone off again!!

Now fully clothed, I've disconnected the vehicle battery. This I presume resulted in the siren running on the back up battery, which must be fubarred as the siren tone went very slow and quiet before giving up completely.

Any pointers or help would be much appreciated

[StarmistBlue400]

This happened to mine when the tickle charger died and the battery went flat. This caused the battery back up to kick in and the siren didn't stop until it died. I disconnected the siren and had to buy another one but when I fitted it the problems persisted. In the end David Fairclough at HF Solutions sorted it all out.

[s p a c e m a n]

Hand in the bottom of the grille on the passenger side and unplug the siren. All of the alarm/locking/immobiliser will still work, you just won't go deaf whilst you figure it out. (I still think it's likely to be the battery in the siren causing it at the mo)

[sparkythecat]

Thanks for that spaceman, siren now disconnected.

What now, how do I disassemble or otherwise check the health of the siren battery?







Important note to self: When disconnecting the battery, always leave a window open and/or the boot unlocked!!!

[Steve_D]

What condition is the main (car) battery?
Could it be low in which case the alarm may trigger thinking the car is being hot wired/stolen.

What were the battery connections like?
If poor that may again be the reason it is triggering and also why it stopped whilst you were messing with the terminal and perhaps improving the connection.

Steve

[s p a c e m a n]

I don't think you'll find parts for the siren even if you did find that it was the battery at fault, you can buy new sirens from http://www.abacuscaralarms.co.uk/tvr-alarms.html (read through thst page anyway to give you an overview of what you've got). I just left my siren disconnected when it started playing up as who pays attention to car alarms anyway?

Steve could also be right, if the main car battery is shagged and dropping voltage it'll also set your alarm off. If it were me I'd just leave the siren unplugged and see if it does it again, think you can tell if it's been triggered by the amount of indicator flashes when you disarm it.

[sparkythecat]

Thanks for your input guys. I'm happy with the vehicle battery and connections. Even though it's not been started for a fortnight, the engine cranks over very quickly and easily.
Appreciate the helpful link to abacus alarms. The bottom nut is rusted onto the siren bracket, but when I do get it off, I'll disassemble the siren and see what I find.

[s p a c e m a n]

Just because it takes five minutes and is easy to do, clean out the interior light switch buttons on the bottom of the door sills. The screw that secures them has got to be earthed, undo it all, clean out the crap behind and make sure that it's got a good earth to it. I doubt it's your problem but it's not going to hurt.