Need help with tail lights going out

[PKblu]

I have lost all functions associated with the rear tail lights on my '90 325is. Brake, reverse, tail lights and etc are all out. However the third brake light still works. I checked the fuses and everything looks fine, plus they are all seperate fuses so it doesn't seem like the problem. I am assuming a ground problem but not to sure were to start.....any ideas?

[PKblu]

Nevermind. Figured it out, it was the diode.