Trailer wiring issue

[Dodge trucker]

I have a 12 1500, reg cab long bed 4.7. ex Fastenal truck. .I have only towed with it a couple of times since I've had it, nothing heavy.
I have. A 6-1/2x 13 utility trailer and an ancient Apache pop up that ive pulled a couple of times each. Usually in daylight.
I think I pulled the utility once after dark last year.
I had to run an "extension cable" since the wiring in the utility (flat 4) was long enough for my Dakota and my Durango but not to reach the factory trailer in plug on this 12. I just fixed that issue today, rewired my plug and added length to it. I need it tomorrow.
I'll be pulling 100% during daylight an hour away and back. Brake, turn and 4 way work, running/Park lights don't.
But they do when I plug in one of my other tow capable vehicles so it's the truck end. I've traced it to a dead brown wire to the back of the trailer plug on the truck side. All lights except 1 license plate light work on the truck, with or without the trailer plugged in. And that license plate light socket is corroded. Both of those bulbs in the truck were shot, replaced the one I could.
I also looked in the underwood fuse box, found fuse M14 missing, legend said it has something to do with trailer tow. All other prongs in both the 7 way and the flat 4 on the truck have power and ground when commanded. Just the "running light" terminal in both the 4 and 7 way are dead at the bumper.
Is there a common spot for these to corrode or get snagged and broken?

 

[Daily Driver44]

It sounds like it may be a fuse possibly???
Coming from the 18 wheeler side of the house, the big rigs separate running lights from marker lights in the interest of amperage draw. This is why there is a 7 way and a flat 4 on the truck. ALSO the do sell adapters to adapt the 7 way down to a 6 round. RAM likes to run the brake lights and the turn signals together. This leaves the marker and the electric brake. The electric brake wire is commonly on the center pin,
With all that said, and depending on how many running lights your running on the trailers, it is conceivable to run both of the running lights on the same wire, again as long as its just corner lights.

hope this helps!

 

[Dodge trucker]

I checked fuses, there were 2 listed on the underside of the fuse box cover that said something about "tow". One (M14) was missing. Test light said one side of fuse slot is "hot" with fuse out. So I added the missing one and no change. Brake and turn work as intended.

 

[csuder99]

J14 is a cartridge fuse for the trailer marker lights, M14 is a mini fuse but it's listed as backup camera so no surprise nothing changed. Did you check the cartridge fuse ?

 

[Dodge trucker]

Looking on Mitchell on demand wiring diagrams that M14 directly feeds the brown terminal on the 7 pin plug. So I definitely expected that pin to come alive when I added the missing fuse.
I have no backup camera so that wouldn't come into play.
I didn't have access to Mitchell from home on a Saturday night when I first discovered this, but looked today at work.
The underside of my fuse box cover said M14 (not J14) was something to do with towing.
I didn't hear a pop when I put the fuse in I guess I'll check to see if it blew out again ...

 

[Dodge trucker]

Nobody?

 

[csuder99]

See my comment above, did you check the blue 20A *cartridge fuse* J14 ? Have a close look at the fuse cover, there should be both J14 and M14 listed. Because of the possible confusion Ram completely changed the fuse numbering to a single FXX list in 2013.

 

[roadrnnr]

I have the same problem My Trailer plug is dead. I unplugged it from behind the bumper and no power from the harness.
I also checked J14, My Fuse box does not seem to line up with the pic in the manual so I pulled all three 20 Blue cartridges out and checked them with a OHM meter and they all have continuity.

The lights were working. But when I plugged in the trailer this time they went off and on and then completely off and I can't get em back on and now no power at plug

Any body got a wiring diagram for a 2011 1500 trailer circuit?

Is there any other cartridge that is for the trailer lights besides J14?