Originally Posted by rubicon327
Ok your colors and functions match what is expected at the 7 pin and carried back through the trailer. Yellow is unused because it is for reverse lights. Not sure why they did the grounds that way. I guess my linked post is really only helpful if you are wiring in a flat 4 plug with full functionality.
RV's would have to be different.
I'm used to bucket trucks. pole haulers and generator/equipment trailers as far as checking wiring.
I did not realize there are three not two wiring standards.
I was going with traditional not rv. We used it and commercial.
I never have had to mess with the wiring on anything I owned other than boats and they use the 4 pole wiring. You threw me with the left being red and yellow being reverse so I had to go look.
Now it makes sense.