Wiring Diagram for a 7-Way Round Pin Trailer Connector on a 40 Foot Flatbed Trailer

Question:

I need to see a wiring schematic to wiring a 1985 40 ft flatbed trailer. I have seven pin round connector. What I need to see is where each wire goes and how it is connected to the lights on the trailer. Is there a book or easy diagram to follow?

Expert Reply:

I do have a handy trailer wiring FAQ article that would be perfect for you. I have included a link to it. I have also included a picture that shows the typical wiring diagram of a 7-Way round pin trailer side connector. As you can see, the 7-way round pin trailer connectors do not use the typical pin functions. The round pin style connectors are typically used on heavy-duty trucks which are wired differently from typical RV or equipment style trailers. You can wire a 7-way round pin connector any way you want, you just want to make sure it matches the 7-way round pin connector on your truck.

You can also use Jacketed 7 Wire, # DW04914-1, if you need to replace the wiring on the trailer. This wire is sold in 1 foot increments.

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expert reply by:
Michael H

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