If it is like the 1996, then this is all you need. I have gone to all of the other sites and this is comprehensive and free, with diagrams, photos and written explanation:
faculty.ccp.edu/.../jettatech/alarmcentralhelp/alarmhelp2.htm
Removing the fuse will be the easiest way to bypass the 1998 VW Jetta factory alarm system. The alarm fuse location can be found on the inside cover of the fuse box.
Pull out the Fuse for alarm system.
I have a '03 and there is an alarm if you leave tour lights on.
you can't, only a dealer can.
it has a turbo diesel model.
You will find the windshield wiper relay on a 1995 VW Jetta GLS under the hood. It is located in the fuse (relay) housing.
In order to the deactivate a factory option alarm system on a 1997 VW Jetta will require special tools. The system will need to be reprogrammed and require a dealership visit to be done safely and correctly.
ebay.co.uk
http://en.allexperts.com/q/Car-Alarms-1513/Car-alarm-2000-VW-1.htm
To disable the car alarm on a 1996 VW Jetta, you can try using the key to unlock the driver's door. This often deactivates the alarm system. If that doesn't work, you can disconnect the car battery for a few minutes to reset the system. Finally, if the alarm persists, consult the owner's manual or a professional mechanic for further assistance.
It is OBD2 in models after 1995.5
Insert key into driver door and turn to the unlock position. This should turn off the alarm.