Where is the speed sensor on a 1999 vw cabrio?

For an automatic, on the top of the transmission. When standing in front of the car with the hood up, the speed sensor will be attached to the top of the transmission with a two-wire connector attached. It will look like this:

http://tinyurl.com/2fpsvwb

It is attached to the transmission by a single T25 Torx screw. Detach the connector, remove the screw and pull the sensor out - you may have to jiggle it a little.