Where do I find the ground

I’m having what appears to be a grounding issue. Not all the running lights work, and directions don’t work unless running lights are off. Brake lights are dim. Can someone tell me where to look for a possible bad ground.
thanks
Jim

I think you need to check the neutral wires which are typically white. Check the connections at your battery, make sure they are tight. Follow the - terminal to a Buss bar and check the connections there. Check all connections that you can find. There are several throughout that are spliced together.
Also, is your truck putting the correct electrical signal to the trailer? Connections behind the truck plug checked? Plug fitting tightly?
Just a few things to look at.

Peace
Dave

To expand on what Cookie said, check the bus bar where the white wires are attached.
On my last trailer, the screw that held the bus bar to the frame broke off and the pressure from the wires lifted the bus bar off the frame connection and I lost the ground.
The factory only had 1 screw holding it down, when I found the problem I installed 2 screws, problem solved.

Hockster

The running lights, brake lights, and turn signals all get power from the truck, through the umbilical. I would think that for the circuit to be complete, you would need ground back to the truck as well, also through the umbilical.

I would check and clean the umbilical connector, and if no improvement, open the junction box under the pinbox and check all connections.

Thanks for the replies. I’m camping With a few friends and will have one of them plug into my trailer to see if it’s my truck that’s the problem.
Jim

Had my buddy plug his truck in. same issues, so truck is out. Opened the wiring box under the pin. That seems ok. Im going to have someone look at it in the next week or so
jim