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Adapter Recommendation for a Motorhome with 7-way Towing a Tow Dolly with a 4-Way


The motorhome has a 7-pin connector with separate brake and turn signal wires the car dolly has combined brake/turn signal the Prius has separate. What do I need to make this all work? Not sure if, legally, I need the lights on the tow dolly as long as the car is on it but I do need to be able to tow the dolly without a car at least occasionally.


Expert Reply:

If your motorhome has a round 7-way with flat, blade-style pins on the inside of the connector you should have combined signals on this connector. Your motorhome may have separate circuit lights, but 99.9 percent of 7-way trailer connectors are wired for combined tail light circuits so I would be very surprised if yours did as well.

You could verify this with a circuit tester like our part # PTW2993 to verify the circuits while a buddy applies the different stop and turns signals from inside the motorhome. Check out the video I attached on how this is done and the diagram I attached for typical 7-way wiring.

If you have a 4-way on your tow dolly all you would need is the correct adapter and you would be able to control the taillight of it. For that you would want the adapter part # PK12716.

If you do have a different wiring configuration on your motorhome or trailer email me back with pictures and I'll help you further.

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expert reply by:
Jameson C

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