Troubleshooting Wire Colors that Dont Match Harness Colors For Connections

Question:

I just bought new led trailer lights with a plug in T type harness the central harness has a black, red, blue and green wire which plug to harnesses for the left and right side each includes a black, red and blue wire which are attached to the lights. My first question is what is the green wire for as it does not go to either light harness. OK, the central harness is too short to reach the tongue of the trailer - the kit included extension wire, but it is not colored like the light harness it has a green/brown and a yellow/brown and a short white ground at the plug. So pls advise what colorsBlk/Blu/Red/Grn from the light harness match up to the extension which I will splice together. I tested the lighting harness on the car grn/yel/brn/wh and it works fine.

asked by: Keith

Expert Reply:

I need to know what harness you are looking for to give you the specific wiring functions of your T-harness, but it sounds like it is working to give you 4-way functions. The colors of the wire are not an issue as long as the functions of the wire and the compatibility of the connectors work. Many manufacturers use different colors based on the wire they have available at the time of manufacturing, so they are often not consistent with other harnesses.

If you have an extension that is too short, I recommend the Hopkins 48" Long 4-Pole Loop with Cover # HM47115. This will give you 4 feet of extension along with some dielectric grease to assist in the electrical connections.

As far as the colors to splice into, you will need to go by the function of the wire and not the color. I recommend using the attached wiring diagram and a circuit tester like # PTW2993 to determine function.

expert reply by: Jason S