I bought a new set of light fixtures (to replace a busted one) and wired them to the trailer's existing wiring. I also bought a little tester that was recommended in a few posts to check the tow vehicle's wiring - it checks out fine. But when I hooked up the trailer, only the right side light fixture worked (all functions) - the left side did not work at all.
So, I figured I would first check the white ground wire on the trailer - it was attached to a rusty bolt on the coupler by only a few bare strands of wire. So, I removed it, cut it, and stripped a new section of clean wire. I attached it with a clean bolt to the trailer frame and tried the lights again. Nothing! Neither light works at all!
Did I not attach the ground wire properly? Did I blow a fuse?