1960 Traveler running lights out

[Woodywhite]

It started with Burning Man last year. Headed out. All interior and exterior lights working find (and have for years). Drove about 15 miles and noted that my side running lights were out but all others worked fine for the whole trip. Trailer has been parked since then.

I just started working on getting back on line but when I checked system:
Tail lights only work when engine running
Step on brakes and tail lights and brake lights go out (and return with release of the pedal)
Turn on either turn signal, and both turn signals blink.
All interior lights are still fine.
I found a couple of loose grounds inside the cabin, at the front end under the couch. cleaned and tightened, but no change.

I presume it's grounding out somewhere. My trailer doesn't have any access ports where the wires enter the body, so before I go putting one in etc, I was wondering if any of you have advice on what path I should follow when doing my diagnostics.

Thanks

[eddys1959]

I have the same issue on my 1959 sovereign of the road, everything I can find on this is possible bad connection on the ground, going to start with the rear lights to make sure they are grounded.
Definitely
would like to hear from some one who had this issue and corrected it.

[Woodywhite]

Progress to date.
Review of the truck revealed a fuse out in the main fuse box under the hood.
Replaced that and cleaned all the contacts at the harness.
Replaced the plug on the trailer.
Things have improved so that the brake lights, turn signals, and tail lights at work appropriately. The rear left running light now works but the other three running lights are still out.

Onward and upward. Will try to track the running light wiring further unless someone points me in a different direction first.