How to Change Out 4-Way at Rear of Motorhome to Work with 7-Way on Trailer


Hi folks, I currently have a 2007 Thor Hurricane Motor home MH thats set up to tow my Jeep Grand Cherokee. The MH tow wiring to the jeep connects via a 4-pole round connector. I also have a sealed 2 prong connector I believe is for the Jeep brakes. I have an electronic brake control in the drivers cockpit of the MH. I want to use my MH to tow an enclosed 12 foot by 7 foot tandem axle cargo trailer with brakes. The cargo trailer has a 7-prong plug. My question is: What do I need to do so I can connect either my Jeep or the cargo trailer and everything will plug in and work properly? Thank you for your help.


Expert Reply:

Thank you for the pictures!

What you may be able to do is install the Hopkins # HM47210 on your motorhome to replace your current 4-Way round connector. I'm guessing the 2 wires for your brake controller system are for 12V power and for the brake controller signal. If this is the case then you will need to connect the following functions on your motorhome wiring with the following wires from the Hopkins connector:

White - Ground
Yellow - Left Stop/Turn
Green - Right Stop/Turn
Brown - Tail/Running Lights
Red - 12V Power
Blue - Brake Controller
Purple - Reverse Light Circuit

To ensure that you make all of the correct connections then you can use a circuit tester like part # PTW2991. You will want to either splice/tee the 12V Power and Brake Controller Signal wires on your motorhome (assuming that's what they are) into the 7-Way so that you have the separate 2-Wire connector and use this with the Roadmaster # RM-164-7 system OR you can splice the 2-Wire connectors for 12V and Brake Controller into the Hopkins 7-Way and the Roadmaster # RM-146-7 connectors respectfully (see attached photo for 6-Way connector).

This should work as long as your controller in your motorhome is an electric brake controller that is compatible with trailer brakes. I am not sure what controller you have though so I am not sure if it is compatible. If your controller isn't compatible with electric brakes on a trailer then I recommend using the Prodigy P3 # 90195 which connects to a port under your driver's side dash using the adapter # 3035-P. You will need part # 37185 to complete the wiring on your 2007 Ford F-53 chassis as well.

Let me know if you have any questions and I can help you out further.

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expert reply by:
Jon G

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