4 pin plug 22 OR

So my lights quit working on my trailer, . When I,plug in the 4 pin connector with the built in test lights into the factory trailer plug only the running lights work. Any ideas? Does the truck need to be running to get power to the brake lights etc?
Thanks in advance for any information

 

Quite a few fuses and relays are used with trailer lights.


This is hard to read but is an overview:



The next three are blown-up (easier to read) sections from left to right:

 

Check all fuses. If all fuses are good, then I would suspect a missing ground issue on the trailer is causing problems.

Tail lights will light up without a ground as they can sneak a ground path back through the turn/stop filament.

Are running lights on, but everything goes off when stepping on the brake? That's a bad ground issue.

 

The stop, and turn lights come from the combination meter.
The combination meter portion of towing is power by the 25A towing fuse.

 

Thanks guys, this is just testing the trailer plug on the bumper, research also shows me a trailer relay behind the drivers kick panel