Electric Gremlin must go

Hey y'all my name is Hopeovermope and I got electrical gremlins... All jokes aside I'm going crazy over this so any help would be greatly appreciated.

Truck is a new to me generation 1 Volvo vnl
N-14 motor

My tail lights and license plate lights went out. This was after I replaced the old rusted rear panel and all new lights. It Ran like a charm for about 5 days. Then the lights went out, first the license plate leds then the running lights. TURN SIGNAL AND 4 WAYS AND REVERSE LIGHTS ARE WORKING.

So since I'm over the road right now and have troubleshooted over 8 hours cleaning every 6 pin connecter resplicing a couple corroded wires, replacing/checking fuses/relays, I decided to jump a hot wire from the trucks pigtail housing on back to the tail lights for constant power.

Well as soon as I went to test the jump wire on one of the lights; not only was there not power to the jump wire but no marker lights on the flatbed either ????????? The trailer still has turn signals and flashers. Give me a break!!!!!! Went to fix one problem and created another. What I did was strip the jump wire and stuck it into 11 o'clock female plug, then plugged the plug in as usual. I quickly took out the jumper wire and with a flathead I spread the prongs in the housing to make a better connection. NOTHING.

I'm at a major loss of what to do. I really don't want to throw it at a shop. And I'm still 1500 miles from home. Which even when i get there I'll still have to figure something out.
Thanks in advance to any suggestions or guidance,,,,, safe trails

 

Yea I don't know. I pulled my light tester out and got no power on any of the prongs which doesn't make sense because I got power going to my 4 ways/blinkers/stop lamps. But I never really had good luck with those cheap $5 light up testers. I should invest into a better one

 

Yea I got a little fuse tester that works really good, and I have the fuse maps. So I've tested every fuse in the main distribution center fuse station, the one under the CB in a Volvo. I checked the two 10 fuses that are on the passenger side frame rail mid-way.... Those are good... The weird thing is, when I hooked up that jumper I never even touched the hot wire to anything else,,,,,,, the trailer lights were already gone before I could..... So it's hard to tell what's coincidence and not...

I did find a broken ground wire above the battery box,,,, it's looks like that is the dedicated plug that feeds electricity to the tractor/trailer pigtails. I fixed the ground wire,,,, or at least good enough to see if that was a factor- and odd enough nothing changed