not fishing but boat related.

[Reel_Deal]

my guess would be the fuse under the hood for the running lights. just look at your fuse block in the manual for your truck and it'll show which fuse is for your running lights. this fuse is very bad about blowing. we were up at lake erie a couple of yrs ago and a friend stopped by our campsite. his running lights was out so we got the manual out and found the right fuse. we changed it out and problem solved.

it keeps blowing. i've replaced it 3 times now in as many days. thought i had it fixed but apparently not. unplugged before i put in and brought out, turned auto lights off before hooking and unhooking, and i changed the plug and made sure all splices were tight. might be somewhere else in the trailer.

[Frank]

You have a bare wire, making contact on your trailer, or somewhere .also those fuses are normally 20 amp.

[Frank]

I'm pretty sure it's the brown wire.. probably where it goes through the frame

[Frank]

I never unplug my lights when I launch. Have never had a problem. Just never had to submerge the plug

[Reel_Deal]

I never unplug my lights when I launch. Have never had a problem. Just never had to submerge the plug

i submerge just right over the fender. so no where near the plug. it only happens when i just pulled the boat out, dropped it in, or possibly when i start with them plugged in and auto lights on.

[Frank]

You you have a bare spot or broken marker light wire

[johneye]

if you have the option of the round plug or the flat plug plug the trailer in to the round plug before plugging into the truck the fuse usually blows when hooking up the flat plug round plug doesnt seem to short out when you plug in

[Davesnothere]

As Frank mentioned, most likely a bare spot somewhere. I had the same issue, if sitting still the lights worked for hours, no problem. Hit the road and 10 minutes in the running lights fuse in my '11 Chevy full size. My wiring was old. Obviously, the issue was a bare spot that would make contact as the wires bounced around while underway.

If your wiring is old, like mine was, you may find the problem is not confined to one spot, and it is simpler and less time consuming to buy the waterproof led full light kit at harbor fright or wallymart or your local trailer shop, etc.

Just my opinion, I chased it a few days and to be honest, the led upgrade was worth the investment. Good Luck!