How Do I Determine The Functions Of Each Wire On My Trailer If They Are Not Color Coded?
Updated 02/17/2026 | Published 06/20/2024
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
(click to enlarge)
(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.
Product Page this Question was Asked From
Curt Powered Tail Light Converter with 4-Pole Flat Trailer Connector
- Custom Fit Vehicle Wiring
- Trailer Hitch Wiring
- Vehicle End Connector
- Powered Converter
- Universal Fit
- 4 Flat
- Plug and Lead
- Splice-In
- CURT
more information >
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on Custom Fit Vehicle Wiring
Jesse M.
2/17/2026
Hey Donald, were you able to test the trailer wires with the wire tester to match each function? Knowing how that worked out could help others sorting through mixed wire colors on their trailers. Your update might make the process easier for the next person tackling similar wiring differences.