Doctor, My alarm don't work...

[cheesey]

hi,
Just got my hands on a Xantia 1.9 SX TD L reg. The one without the keypad just the plip.
Since I have no hand book I have no Idea how it works.
The plip don't work but the red light on key lights
The red flashing LED don't flash on the dash.
All the central locks work.
The key lock under bonnet is on but when I turn the key to off a very weak siren or beep comes from somewhere.
And thats it really for the alarm.
thanx in advance.