Sounds to me like an intermittent short to ground. It tests fine most of the time, but blows the fuse when you hit a bump just the right (wrong) way.
Have you traced the wires to look for wear/pinch points? That is what I would try next.
I agree. Intermittent. Funny thing is that it’s been fine for several years. I suspected my LED license plate light but so far it tests fine and I don’t see any broken wires. I think I even had it out of the circuit once when I blew a fuse, so I sorta ruled it out that way. 10A fuse.
Funny how you can fool yourself sometimes trying to trace short. Thought I was tracking a short as I kept finding continuity to ground as I moved closer to the cab. Then I realized that the front park light bulbs were grounded and I was interpreting that as a short to ground. Haha! Remove bulbs = short went away. I had continuity through the bulb filament and the bulb base was grounded.
Sure tests my abilities but so far I’ve found nothing.
