The brake lights on my 2001 Jetta are out. On both sides the top brake bulbs (assuming the second bulbs are for brakes) were burnt, but the filiments were intact. I figured I'd try to replace them, with no success. Checked the fuse, its fine. In the process of looking, I've noticed that if either of the two upper brake lights in the left/right lights are installed, the top light (above the trunk) won't light but if both are pulled out then the top light will light up. I've read on the archives, and it seems like this could be:
1) Bad connection with the bulbs. They seemed to click in quite well, how could I check this better?
2) Bad wiring harness. I guess this would be a "take parts off, look" untill I find something.
3) Loose ground wire, same as 2.
Any other ideas? or hints on where to look? There are good bulbs in the lower sockets on both sides. The running lights, backup lights and turn signals all work normally.
Thanks for your help, Josh