Not sure how its hooked up on the gas engines, but on the diesel, there are two limit switches on the throttle (one at each end of travel) that need to be hooked up. Both are in series and both need to be closed to enable the light (5th gear disables it too). If any of the switches is missing or disconnected the light won't go on. On the diesel, the light gets its RPM signal off the alternator "W" terminal. One symptom of worn alternator brushes is a bad W signal which can cause the upshift ligt to stop working.
Again, I don't know what the gas setup is, but its probably similar.
on the rabbits, the upshift light is part of the reverse switch thing on the tranny. If that switch doesn't work (as seen by lack of reverse lights) the upshift lights won't work. If that is OK, next logical steps are the fuse and then the wiring and then the bulb...
This is an older thread, you may not receive a response, and could
be reviving an old thread. Please consider creating a new thread.
VW Vortex - Volkswagen Forum
A forum community dedicated to all Volkswagen owners and enthusiasts. Come join the discussion about performance, builds, modifications, classifieds, troubleshooting, maintenance, new releases, and more!