Passat 92 Gl Factory Alarm Problems

Hi There!
I recently installed an AVITAL 2100 alarm for this car....now the problem I have is that the factory alarm goes off for no reason at any time I think there might be a conflict there.... when it goes off only the horn would sound not the actual siren from the Avital alarm.
Is there any way to kill the factory alarm so I can just keep the Avital 2100?

I couldn't even find which fuse is for the factory anti-theft system, nor a diagram for a '92. If it's in your manual pull it & see if the door locks still work & the car will start properly. Other items may be on the same fuse.