passat 1.8turbo

hi all i have a passat 1.8t 1999 72k ish. has anyone got an idea about my problem since buying the car 2 years ago the alarm is working sort of.when you arm the car from the inside and open the door the horn sound s ... ok but arming and disarm it the four ways don,t flash and i,m sure it,s not the horn that sounds off or am i wrong .they is a siren in the engine bay next to the battery.any idea to what make of alarm is in the passat. and i have a small red light [diode] on the centre console .. don,t look right.http://www.automotiveforums.com/vbulletin/images/icons/icon9.gif