Trailer lights problem

[OhioDmax]

I can't figure this one out ........My 05 will not run the interior lights on my horse trailer, works all the other lights fine ,my 02 also quit running the interior lights but worked all the others ok......Now, my father in law has a Ford that works everything ok and my bro in law has a Dodge that also works all the lights correctly.....I'm absolutely stumped as to what the problem is or what I could be doing wrong......Can't be the trailer as everything works ok for other people?????
Anyone have any ideas??????

[ob_1jr]

do you have your parking lights on your truck? I know that is what I had to do with my enclosed trailer. Although, come to think of it, I had the same problem with my friend's trailer with my HD.

[OhioDmax]

I believe the interior lights run on the auxillary power plug of the 7 pin. On my 02 it worked fine for about 2 years then suddenly stopped. I figured problem with the trailer......well I finally got around to trying another truck and both a Ford and Dodge hooked up and boom, we have interior lights....We tried a voltage meter on all the pins and the auxillary pin wasn't getting any power so I figured that was the problem, probably a fuse.....but to hook up a new truck and get the same thing is a real bummer.
To answer your question, yes, although I don't know that it would make a difference. Now, all the other lights work as they should, including brake light, turn signals etc......so I'm just stumped......My bro in law was just on a RV site and apparently this has been a problem for others as well so I'm hoping to get some feedback by someone who has seen the same? I turned the light to the on position thinking maybe the auto-on feature had an effect but I got the same result, no interior lights???

[ob_1jr]

Isn't there a fuse panel by the steering column? I can't remember what fuses/relays are in there. Maybe that could be something to look at. I think I had to change a fuse under there for one of the trailer lights not working. (parking)

[OhioDmax]

We had thought of that as well. We used the voltage meter and tested and checked every fuse that we could find in the book that had anything to do with trailering. We finally came to the conclusion it was one of the maxi-fuses and I called the dealer to see what it would be to have it checked and I was told 60 bucks just to hook it up. Then I thought I would just take the book in and replace the maxi's that had to do with trailering, just to try to save a few dollars.....To me 60 bucks is a little silly to tell you the problem is a $4 fuse.

[ob_1jr]

I thought I read on thedieselplace.com that stud 1 under the hood fuse block didn't have a fuse in there. They installed a fuse there and it worked. I also just read in the owner's manual that you are not supposed to have one there if you have the dual batteries and diesel. I will do some more searching on this on the other site. It seems to me that someone over there was having problems and that fixed it.

[ob_1jr]

Ok, I got a good answer from the guys at thedieselplace.com. There is supposed to be a fuse (square block looking one) on stud 1 under the hood. You should have a blank fillter block there. Mine is red and says B+. They said that the fuse should be with your Trailer control wire harness. They say it is a 40amp fuse. Check out this thread:http://www.dieselplace.com/forum/showthread.php?t=45859

They say that this is should fix the problem.

[OhioDmax]

Thanks so much for the info/help.......I'm at work now but on first break I'll see if I can't find that fuse and install it......Makes my situation make sense at least.

[OhioDmax]

Went out......found the fuse.....installed in stud1 position......can't wait to get home and plug in the trailer to see what we got.......thanks again for the assist...

[OhioDmax]

Plugged in the trailer and had lights.......thanks for the help