Determining Wire Functions on Old Horse Trailer

Question:

Im trying to redo the wiring on my old horse trailer and from the plug in I have all but two figured out the colours are brown black blue yellow and orange all but the yellow and orange I have put into the correct spots but from the old plug in the yellow and orange should be red and white so which one goes where does red and orange go together and white and yellow or is it the other way around? Also having a major ground issue as well

asked by: Leslie

Expert Reply:

Wire colors are not always the best method for determining functions. The color wires you mentioned having on your trailer are not standard, but even when looking at standard wire colors, it is always best to actually test them to ensure you are making the correct connections. Trailer manufacturers will sometimes use different wire colors and a previous owner may have installed aftermarket wiring, so going by wire color alone can lead to issues.

I recommend testing all the wires on your trailer, even those that you have already connected. You can use a 12V battery and a jumper wire. Simply touch one end of the jumper wire to the positive post of your battery and the other end to each wire on your trailer to see what each circuit illuminates.

Most likely this is why you are having a ground issue, as it's very possible that the wires you have connected are not actually matched up properly. If you are unable to resolve the issue, please let me know and I will be happy to look into it further. I have also attached a trailer wiring article that you might find helpful.

expert reply by: Chris R