How to Determine Trailer Wiring Circuits on a Trailer with Non-Standard Wire Colors

Question:

My trailers wiring has 4wires white,black,white and black,red and black, half way down length of trailer there is a connector to split to both back lights, same 4 colours go to each light, do all 4 colours from each side connect in the middle like for like I,E black red /black red to black red thanks

asked by: Les C

Expert Reply:

The trailer wiring colors of your trailer certainly aren't the normal colors used. Because of that you would want to use a circuit tester like part # PTW2993 to test all of the wires when the trailer is connected to a tow vehicle and different taillight circuits are applied. That would be the only way I can guarantee you will know the function of your trailer wiring. However, most likely the colors would all match up like you suggested.

I attached a help article on trailer wiring for you to check out as well.

expert reply by: Jameson C