I have had no problems with the truck charging my trailer before this week. All of a sudden it just quit.
I checked the trailer 7 pin and the middle connector (aux) is not pushing any power to the battery.

I then pulled the 30 amp fuse for stud #1 and checked to see if it's blown. It was fine.
I then removed the 30 amp fuse from stud #1 and checked the spade terminals inside the box itself, it had no power coming out of it. So stud #1 is giving no power output to the fuse or inside the box.

Am I missing something?

Im going to guess there is a 30amp relay somewhere with a set of burnt contacts that powers up 30 seconds after the key turns on or the engine fires up.just a guess.

good luck

drive safe

Give me a minute and I will look up the wiring diagram and let you know.

Gosh guys I dont know what to say besides thank you so much. Im kinda lost, i hadnt heard anything so i called the dealer. They need to check out some other stuff and I'll have them look at it.
I was towing my trailer the other day and the battery light had come on and i was on a one lane road of road construction so i couldnt pull over. it stayed on for like 2 minutes.
Then when i pulled over to check it out, it went out....

It looks like there are two fuses for the trailer.

First one is a 40 amp mega fuse and there is a 40 amp fuse at stud 1 in the fuse box under the hood. The wiring diagram doesn't exactly say where the 40 mega fuse is, but I would thing that it is also in the fuse box under the hood.

The wire from the positive side of the aux battery goes to the mega 40 fuse.

I hope this helps. If you would like the diagram please let me know.

Heres the wiring diagram

Thank you so much, I really do appreciate all your help; I'm going to take a look around out there while I still have some light. I wonder if that's what it is, it's the only thing I can think.

thank you again for all the help; i really appreciate it.

Check for power to the relay and with engine running check for power on the other post of relay. Not the first time I have seen a relay go bad.

I dont belive there is a relay, its always hot.
Also the Pos +12 volts is NOT on the center pin of the 7 way, that is back-up lights.
+12v. is oppsite of the ground in the socket, the socket cover should list each pin.
PM me if you need a diagram, I dont have one on the pc to post.
Mike

Are you getting power at the trailer plug? If so, your problem is either with the connection to the trailer or the trailer itself. I only ask because that is why mine quit working.

Mike and Tom thank you for your help, out of no where it works, I took all the battery terminals off the trailer and hit them with a wire brush and all is well as of now... I think something may have been loose as there wasnt alot of corrosion but the wires would move around quite easily before and now they're torqued down real tight.

I thought the trailer battery charge was always hot as well.

I wondered why I had no power to the trailer when it was hooked up to the truck, too. I always thought the lights and everything should work when the truck is plugged to the trailer.

Well, lo and behold I check underhood and the 40-amp fuse in the box is blown. Will know for sure tomorrow after I buy and install a new fuse. (I'll buy extras, too)

Did anyone figure out where this 40-amp "Mega-fuse" is? On the diagram, it shows somewhere by the aux battery.

I have been trying to figure out my trailer lights as well. I still have the orange plug in the 40A mega stud #1 so I know that is why I don't have 12V trailer charge (need to buy the fuse). My problem is that I have both turn signals at the bumper female plug but no tail light voltage. I can't find the fuse for that one unless it's under the hood.

anyone? anyone?

Found it -- blown 15A under hood fuse box "trl prk" (park lamps? *shrug*). However, still no werky at the bumper! Tore into the rear bumper connector and finally got voltage at the harness. cleaned + di-electric grease VOILA!

never under estimate corrosion - even on a 2 year old truck ;)

Now I need to find that CHMSL connector for my truck cap that isnt under there

I dont have any power to my 12V pin on my plug either. This is the first time I have had to use it. My wife just bought a Featherlite gooseneck, and we have no interior lights or power to the breakaway. So I put a test light on the 12V pin and no power. I think I might need to get one of those 40A megafuses. It goes in the underhood fuse block correct? And there is an orange plug in it now from what I read right?

If it's like my 06, I replaced the orange plug with a 40 amp fuse and everything worked. The orange plug was in the fuse holder under the hood, at the top, to the left in the corner.