[Coley]

Okay...here is a annoying, troubling electrical light situation I once saw and experienced through a lot of frustration..AND...it wasn't anything to do with grounding:

I had very weird lighting situations coming in my vehicle....the wrong lights working on the wrong circuit...and then stopping others, lights going out, coming on, under various electrical events, etc.
I re-grounded everything and it still wasn't working or changing anything.

I was ready to completely ready to re-wire the major lighting and screw the rest.

Guess what it was?......lol.
It was one of the filaments in one of the 1157 (dual filament) light bulbs.
It had broken and shorted/touched across the other filament circuit inside/within the bulb itself.....which needed some close visual inspection to actually see.
This produced all sorts of weird results by providing a brand new path for the electricity through the other regular circuit....

Anyhow, long story shortened....I replaced that 1157 bulb (checked the rest) and my problem immediately was gone. Cheap, quick, simple....but damn it had me going and confused for weeks.

....so, maybe take a quick look at your 1157 (dual filament) bulbs around the perimeter of the truck and make sure you don't have this situation.
Easy to check...

My two bits.
Coley