I recently purchased a 2001 dodge neon thats missing the radio. When i unlock and open the door the alarm goes off untill i start the car. Car runs with no problems.

SOURCE: Looking to disable the alarm system for a 1996 Jeep Cherokee Sport

you need to find out which wires go to what like the ones going into the alarm and the ones coming from the car u might have to put them back together..hopefully they are color coordinated for you good luck

SOURCE: My car alarm is blinking

Your Central locking wire is short from any one door side. Please check it properly.

SOURCE: 1998 Toyota Camry car alarm keeps going off.

I have this same crazy problem with my Camry. When you push the button then open the door on the driver side really quick, the alarm starts to blow off. So what I used to do everytime is push the button to unlock all the doors then open whichever door you want. It won't scream. Try it.

SOURCE: 2001 jetta alarm doesn't disarm when i unlock my car

you can buy a factory vw key on ebay and have the dealer program it to your alarm. i had to do it that way when my key broke. it is cheaper than a new one from the dealer. type 01 jetta factory key on ebay.

SOURCE: VW 2000 New Beetle door sensor/car alarm goes off when doors open.

I found a thread - http://forums.vwvortex.com/zerothread?id=1542461 that details the repair of the soldering on the key lock door module. Our 2000 new beetle had the same issue. Also sometimes it refused to start. Soldering pins fixed it all.

Also see http://forums.vwvortex.com/zerothread?id=1015107 for releasing window from track, And door handle from inner panel.

I ripped the door apart and re-solderd the pins. I only had one pin with cracked solder but two others looked thin so I did them while I was in there. It's about a four or five hour project if you have all the tools. (8mm triple square also called an 8mm internal was the hardest to find - Also needed Torx T8 T10 T15 and T30 plus Philips Screw Driver. )
Project is difficult but not too bad for the mechanically inclined. A 7 on a scale of 10.
Since re-soldering pins - no more issues! My guess is that a VW dealer would get $200 for a new moduel plus 5 hours of service time for this gig - easily a $500 to $1000 bill. My cost - several new tools - about $25.00.