Wiring Up Trailer 7-Way that Uses Non-Standard Wiring Colors

Question:

Our plugs colors are green, black, 2 white. 1 is bigger than the other. Blue, red, and brown. 1 cannot find a color code with those colors. All I have found has a yellow color.

asked by: Mary G

Expert Reply:

Unfortunately not all people will use the standard wiring colors when wiring up a trailer connector. This happens pretty frequently and the solution is to first determine what the wiring is and then wire by function according to the attached diagram. So to do this on a trailer you have to take a jumper wire from a 12 volt battery positive post and apply voltage to all of the pins to see what they activate. You might graze the pins first as the ground circuit will spark. Most likely this is the thicker wire though. Or it's the 12 volt accessory circuit or brake output.

expert reply by: Jameson C