I don't think there's any real standard and if you ask Google you get different color codes. I always make sure I take a picture of the plug or harness before I tear anything apart so that I can match it all up when I install the new hardware.

Below are two different color codes for the same familiar 7-pin interface:

And here's the inside of the junction box from the harness I put on my trailer back in CA (plug started to separate from the cable and it was too short anyway, so I bought a whole new box/harness with a 10-foot cable). Looks like it uses the first color code with yellow for backup lights (which my trailer doesn't have).

 

Same jct box I'm trying to stuff about 20 wires in, that's a joy.

And neither one of those diagrams you found show brown, green and yellow as the light wires, which has always been normal to me. I suppose maybe we could find even more combinations if we tried?

Maybe I'll get it finished up tomorrow. Just have to wire in the breakaway then get a couple dead corner markers working again and I'm done.... I think.

I hate wiring. I'd rather change a crankshaft out of a truck.

 

Same jct box I'm trying to stuff about 20 wires in, that's a joy.

And neither one of those diagrams you found show brown, green and yellow as the light wires, which has always been normal to me. I suppose maybe we could find even more combinations if we tried?

Maybe I'll get it finished up tomorrow. Just have to wire in the breakaway then get a couple dead corner markers working again and I'm done.... I think.

I hate wiring. I'd rather change a crankshaft out of a truck.

Electrical is the only thing I'm any good at. I can't even paint. No clue how to hang drywall.

Doesn't the second graphic match the color code you mentioned? Similar to a 4-flat, I think.

 

Ran into this exact problem with an E-trailer plug/cable assembly for the trailer side and nothing matched. Discovered that you had to print the wiring diagram from them with an explanation of which color did what.
Maybe they do it different in China where the crap is made?

 

Yeah my memory isn't that good but I think the second graphic you posted is the same or very close to the new pigtail I bought. I guess I just don't understand why there's a standard for trailer wiring but the pigtails are nothing like it. Maybe they match truck harnesses?

@jdwarren, I'd gladly hang your drywall and lay paint for you if you could take care of all my electrical/electronics issues If there's anything I dread more than 12V electrical issues, it's electronics. We just bought an automated mattress the other day and when the salesman said something to me about loading an app on my phone, I just told him to talk to my wife. My phone is already about one more app away from flipping me the bird. It wants me to load 20+ updates but I won't do it because I know it'll kill it then I'll have to deal with a new phone.

 

Okay I'll bite. WTF is an automated mattress?

 

Set the alarm and it throws your butt out at a certain time?
Or alerts your kids when mom and dad make like rabbits?

 

there is no wire color standard for trailer wiring. if you have a trailer connector you do not have a color code for you need to use a test lead to figure out what wire is actually what on the other end. then label each color accordingly

 

Yip, that's what I did, about all you can do. I rolled that SOB out of the shop today with everything working correctly. Keeping truck and trailer lights working around that place is a never ending fight.

 

The diagram with the red LT - brown -RT and Tail Green and back up -yellow is
The Std RV Wiring code for a 7 wire harness an has been for over 40 years
I owned an RV Dealership for 46 years
a lot of after market wiring harness's started using Flat 4 code Yellow LT-Green RT -Brown Tail
-white Ground

 

The diagram with the red LT - brown -RT and Tail Green and back up -yellow is
The Std RV Wiring code for a 7 wire harness an has been for over 40 years
I owned an RV Dealership for 46 years
a lot of after market wiring harness's started using Flat 4 code Yellow LT-Green RT -Brown Tail
-white Ground

That may be true for RV's- never had one nor worked on one but in 40+ years of pulling utility and horse trailers they have all been left yellow right green tail/marker brown white ground blue brake.
These color usages are not "aftermarket" as you state but a trailer standard (except RV I suppose) that has been on every trailer I have ever owned, pulled, or worked on. Even my MUTT trailer light/brake tester uses this color code.
If the colors are to be whatever then why use colors-- just make'em all one color and let the user figure the circuit out and tag them accordingly.

 

Like @JonM21Ltz mentioned, I make my own diagram, pin positions are the only thing you can rely on being the same with aftermarket plugs. Ringing the pin/wire with a meter saves a lot of headache.

Would be even less headache if the old rv standard was adhered to .

@blythkd1 we really like our sleep number, I passed on anything smart enough to need a phone but we like it.