How Do I Determine The Functions Of Each Wire On My Trailer If They Are Not Color Coded?

Question:

I bought Trailer Wiring 7-Way Upgrade Kit ITEM ET7WK. My trailer has 6 wires. Looking at my pics your wiring on the right and trailer wiring is on the left. I watched the wiring video but some wire colors are different. The yellow, green, and black wires on your wiring is not connected. The trailer wiring does not have a black wire. I attached the trailer blue to harness blue. Please look at pictures and help me get the wiring correctly wired. Thanking you in advance.

asked by: Donald R

junction box
(click to enlarge)

Expert Reply:

Hello Donald, thanks for reaching out. Since the wires on your trailer are not color coded to the typical standard, the best way for you to determine the correct function for each wire will be to use a wire tester such as part # PTW2991. You can probe each wire and use the process of elimination to determine the function of each wire. On the trailer side it can be helpful to trace the wires back and see where they go.

expert reply by: Jesse M