So I just found that running lights not working on any trailers I hook up to my truck, all the other lights are working though, what could be the cause here?

 

The normal 7 pin round socket, or the flat 4 one? Both? All clean in there?

I would get a simpe 12v test light, and test the running light pin on the truck. That is about 11-o'clock on the 7 pin round. If you've tested multiple trailers, chances are pretty good the issue is with your truck, but this way you will know for sure.

 

Yea it's on both, used a tester and it shows no signal. I also just checked the fuse under the hood I believe #36 and it looks good so I'm stumped.
Wondering if I'm even looking at the correct fuse, which one of these is it?
34 25A* Trailer tow park lamps.
35 20A* Trailer tow stop-turn relay fuse.3
36 25A** Trailer tow lamps module.

 

Based on those descriptions, I would say it's #34. Park lamps and running lamps are synonymous these days. #36 could be just about anything too though.

 

#34 #36 both look good on my truck.. This should be covered by warranty though right? I just don't want to deal with taking into dealer if a simple fuse will fix this.

 

Well just so that this is here for future searches, anyhow I did find that fuse #34 was bad and replacing it fixed the issue.

 

r34 is the fuse for the parking lights for both plugs. There is a relay under the hood in that fuse box which should pick up when you have the truck parking lights turned on.
The relay would be right next to fuse 96,97,98.

 

Good to hear you solved it.

Now to figure out what caused it