A4 2.5 TDI year 99 or 00 Alarm problem- goes off on its own

[a4driver]

Hi my first post

ive a 99 or 00 2.5 TDI and the alarm goes off, everytime i lock the car within an hour i dont get any flashing indicators and it doesnt matter whether its locked with key or fob. but within an hour of being set then beep beep (not the horn), same story even if ive turned the interior sensor off via the button near the drivers door.

it doesnt matter where ive parked it goes off.

ive got one of those vag-com cable things but it doesnt give explanation, i did have a couple of errors relating to alarm but cleared them to get a clean sheet.

ive resorted to carrying a 10mm spanner and disconnecing the battery in the front every time i stop.

ive done a search on this forum and maybe i need to test out the alarms battery backup? where is it?

Im skint at the moment thus dont want to have to be at the mercy of a garage, without roughly knowing whats wrong.

any help would be apriciated.

[a4driver]

ive worked out its the battery in the siren, this weekend im gonna set the alarm off and hunt the siren down and rip it out.