My tail lights on my trailer quit working. Brake and signal lights worked fine. All lights on my truck worked fine. Being old school I immediately began looking for problems with the trailer lights and specifically for a ground problem. After spending 1 3/4 hours with my volt meter checking continuity and checking for worn spots in the wiring insulation i realized the problem was not with my trailer lights. After checking the fuse diagram I found that there are fuses that are specific to trailer lights. (GM calls the tail lights "running lights")
Took less than 5 minutes to locate and replace a blown fuse.
I'm sure there are several threads that point to this situation but I didn't find a thread specifically relating to this problem.
So if you have partial trailer light failure save time and trouble by checking the fuses first.
