I have a 1984 Audi 4000 and the taillights are giving me trouble. When i push on the brake it is fine, the same when i signal each side. for example i put the left signal on it comes up with the left signal but when i push the brake the left signal stops and the right comes on without me changing it. and vice versa. Anyone have any ideas on what it could be? I dont know anything about vehicle electronics.

Thanks

 

Try adding an auxiliary ground for both taillights. I usually do this by connecting a wire with a female terminal to the bulb holder (should be a male terminal already there) and connect the other end of the wire to one of the light assembly mounting studs. Don't tighten that nut too tight and risk breaking something! ;-)