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I saw this on FB this afternoon and thought many members here have trailers and this could come in handy. I have a car trailer and as it ages it seems to form wiring problems more often. This summer I'm going to do a complete rewiring and paint job on it.
Easy tip to remember
yellow is left turn/brake since there the letter "L" is in yeLLow and Left
green is right turn/brake because the letter "R" is in gReen and Right
One note, I was told horse trailers don't have the same wiring as a car or utility trailer for some reason. I think the brake wire is different. I had a friend who bought a truck from a rancher and when he hooked his car trailer to the truck, I'm not sure, but I think he told me when he turned on the running lights the trailer's brakes activated. Again, I'm not sure.
that's just the 2 different in light duty RV, there are about 20 standards (if you count europe, etc)...
etrailer has a tech page that has the 4 blade, 5 blade, 6 round connector/round pin (what my ranger has - it predated the most typical 4 blade being a thing), 7 round connector/round pin (heavy duty agricultural), and of course 7 pin blade (light duty RV)....
that's just the 2 different in light duty RV, there are about 20 standards (if you count europe, etc)...
etrailer has a tech page that has the 4 blade, 5 blade, 6 round connector/round pin (what my ranger has - it predated the most typical 4 blade being a thing), 7 round connector/round pin (heavy duty agricultural), and of course 7 pin blade (light duty RV)....
not even discussed it the foreign stuff (7 pin round pin / round connector half reveresed gender - europe)...
Lets keep it simple since most of the FTE brotherhood lives in the US and have either the flatblade four on their yard trailer or the round blade on their car trailers.
One note, I was told horse trailers don't have the same wiring as a car or utility trailer for some reason. I think the brake wire is different. I had a friend who bought a truck from a rancher and when he hooked his car trailer to the truck, I'm not sure, but I think he told me when he turned on the running lights the trailer's brakes activated. Again, I'm not sure.
I had a similar thing happen when I brought home our 1975 Airstream Argosy. It was wired as the Traditional way and as soon as we started the truck, the backup lights came on! A previous owner had clipped the brake wire so they were not locked up continuously. A new pigtail and now everything including the brakes work!
The nice thing about the 2 different 7 pin blade standards is that while the color is different the functions are the same, so a trailer entirely wired in SAE will hook up and work fine to a tow vehicle wired entirely to RV standard.
I have also seen an RV connector on a horse trailer wired to agricultural standard so I have to assume there was a truck somewhere used on a farm with the rv blade but wired to ag standards. I used to get trailer wiring stuff from a place called Rancher's Supply (for the farm), once they disappeared you have tractor supply or harbor freight and can only get blade connector ends so I see why it happens.
Since the 4 pin is also kinda quite common and has been mentioned and this relates to a 7 pin blade as well here is a nice tight little solution that keeps you from having to wire your tow vehicle up to both standards and having multiple connectors on the rear end:
I thought about buying one of these (until I saw the price) Then I thought I might build one. But I don't need it that often and have way too many other projects that need to get done first; https://www.northerntool.com/product...yriZx7kQ&gQT=1
dunno if you caught it, but I followed that link, that is for the 7 pin - round pin agricultural heavy duty....
And yeah at $185 that is too spendy for my wallet for what it is...
regarding post #5...
I ran into this same illustration recently while replacing my wiring on my trailer, really got confused which one to use. But if you look at the pin function in both the SAE and the RV connectors, each pin function is the same regardless of the wire color. I guess the functions have to be the same... so you have the option to tow a camper or flatbead trailer without rewiring.
Yes, if done properly, they physically (but not by color) interchange. However, many are not aware of the nuances and then follow the wrong color scheme for the physical layout and then you get mayhem.
