After I bought my truck, the first time I connected the wiring plug from my trailer into the truck, the right turn/stop lights on the trailer wouldn’t come on even though those lights on the truck worked. The first thing I checked was the fuse box, but the fuse for turn/stop was just fine. I tested the plug receptacle on the truck and figured out that it was a problem with the truck’s wiring (not surprising since all my trailer lights had worked when I towed with my old F-150). I monkeyed around with the plug and wiring, but couldn’t figure anything out, so I just left it alone. I never towed the trailer very far from home anyway, so I wasn’t too worried about it.
Today, I was determined to get the lights working since I’m going to pull the trailer 200 miles round-trip next week, and a lot of that will be on the interstate. After spending an hour and a half lying on the ground under my truck, tearing apart the trailer wiring plug, and tracing wires all over the chassis, I realized something: Ford sucks. I gave up again because I just couldn’t find any problems, but I decided to search this forum to see if anybody else had had the same problem. It turns out that Ford hid another fuse box under the hood. That’s not somewhere I would have looked, especially considering there’s already a fuse box under the dash. Oh well, live and learn–I simply replaced a blown 15-amp fuse and I’m good to go. I’m just glad that now I’ve got working lights on the trailer, so I’m no longer worried that somebody will rear-end me on the highway.