[Pathung]

I towed a friend's trailer for a few days - first night all lights worked, second night running light no longer worked, while everything else was fine. We checked the trailer and discovered that its harness had a grounding problem, and possibly popped a fuse on the truck.

Question: what number fuse and what AMP should I look for in my 2001 7.3L? I've thus far found a 20 amp fuse that seems burned out, marked #4 under the hood; is this it?

Thanks.