Flippin-Out, thanks for the reply. I might not have asked my question clearly. I am quite handy and completely understand trailer wiring. I don’t use crimping tools as the connections come lose eventually no matter how good the crimping tool and cause all kinds of trouble, I solder all of my connections. The basis of my question was basically if y’all knew a good place to buy the setup I need. I can’t find the type wiring I need. I need a wiring harness like 18 year old original one still on the trailer. It has 3 white wires, one for the trailer ground, and one for each the right and left side to ground the lights to the vehicle vs the trailer frame and a blue wire in addition to the standard green, yellow and brown wires. The three wire lamps that are currently on the trailer have a ground incorporated vs grounding to the frame a green or yellow for right or left and a brown for running lights for a total of three wires. I really would like to keep that same setup but all of the light kits don’t have the ground wire incorporated into the full length of the wiring harness and make you ground the lights to the frame. I have surge brakes so the blue wire is needed to bypass the solenoid so the brakes will release when in neutral. Etrailer and Amazon seem to have the best selection but would like to know if there are other options out there.
Your reply about crimped connections borders on comical. Clearly, you do not understand crimped connections. I've got them on a boat I've had over 20 years, and haven't touched them. Same for the trailer that boat sits on. Solder can be good for some things, but it requires even more skill to do correctly, and insulation from future shorts becomes paramount. A little tidbit for you if you want to ponder reliability of crimped connections: Every aviation maintenance/repair/build specification I've seen calls for CRIMPED connections. I'll let them know that those are unreliable. (I've read studies that showed the soldered connections are more problematic than crimped ones, but I guess you found a different study?)
Ground is Ground is Ground. You don't have 3 Grounds. The vehicle's 12V system has a common reference point; we call that GROUND, and you it common to the trailer with a white wire on the frame as described. Your trailer is Ground once the white wire is properly attached to the frame. Any point on the frame at bare metal is then, well, GROUND once again! Unless you have a tilt-frame trailer, there is no need to run dedicated wires to the rear lamp housings. If it's a tilt frame, one bonding wire near the pivot point will insure both parts are also in electrical continuity as Ground. Unless a person was thinking they would avoid issues (that don't exist in a proper installation), I see no reason whatsoever for a wired Ground when a frame is available.