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How to Make a 6-Way Square to 4-Way Flat Trailer Wiring Adapter  


We have a 2004 Monaco RV with a 6 pole square socket. We have a utility trailer to pull our toys that has a 4 pole flat plug. We are unable to find an 6 pole square to 4 pole flat adapter.


Expert Reply:

The 6-Way square trailer connector is not used by a lot of trailer manufacturers. A lot of Jayco trailers may have them but mostly you come across the 4-Way flat, like what you have on your trailer, and the 7-Way blade for RV applications.

What I recommend is to convert the 6-Pole on the Monaco to a 4-Way. You can do this very easily by removing the 6-Way plug, and then testing the wires for function using a circuit tester like # 3808 if needed before installing them in a new 4-Way, # HM48030. The 4-Way vehicle end functions will be oriented in the 4-Way as follows:

Exposed pin = ground (white wire on harness)
Next pin = running lights (brown wire on harness)
Third pin = left turn and brake lights (yellow wire on harness)
Last pin = right turn and brake lights (green wire on harness)

The other wires can be taped up and stowed out of the way.

Since so many more applications use the 4-Way flat, this will be the ideal option. But, if you do not want to remove the 6-Way on the RV, you can make your own adapter. You will start with the 6-Pole Square Trailer Wiring Connector Kit, # 37995. Plug the trailer end into the connector on your RV, then use a circuit tester like # PTW2993 if needed to test each wire.

Next, use the vehicle end in the Quick Fix (TM), # 48195, and insert the wires as described above. The other wires you can tape up because they will not be used by the 4-Way. Once you have made all of the connections you will have made your own adapter.

expert reply by:

Rodney S.


I have a bunkhouse motorcycle camper with a 6 pin flat My motorcycle is a 4 pin flat. Which wires do I connect to have all functions on the trailer?

Etrailer Expert

Chris R.


If it's a true motorcycle trailer, then it likely has separate wiring - where each wire carries a single function (standard trailers combine the turn and brake light circuits). Since we can't be sure though, you'll want to test the wiring with 12V power to see which light each wire illuminates or simply trace them along the trailer to see where they go. If it's separate you will need to wire a converter like # 118158 in line with an adapter like # 30637 for proper hookup.

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