7pin connector to 3pin attwood

[rynd72]

I bought a new truck and it has electric already run to the bed (although it’s at the back versus the front). Does anyone know if and how I can connect my Grandby 3pin attwood (or change it) to the 7pin already wired to the bed?

 

[Wandering Sagebrush]

Why not, all kinds of hard side campers and fifth wheels use it. I would ensure you have an isolation device, and that your seven pin is not hot when the truck is off (personal preference). I had both the seven and three pin in my old F250, but would have preferred that FWC just change the male plug on my now sold Grandby. FWC was not receptive to the customization.

 

[Trailbob]

I would cut the existing plug off the FWC and wire on a new 7 pin plug to match the one in the bed. If I remember right, there are only three wires coming out of the FWC (positive, negative, and running lights). It would be simple to match it up in the 7 pin plug, or a quick job for an RV shop.

 

[Old Crow]

I've not run into this personally but remember seeing these potential problems with using the trailer connector on Fords...

1- If your new truck is a 2015 or newer Ford with factory tow package, you may have a Smart Trailer Tow feature which could confuse things a bit. This video describes the issue you could run into. The truck may not allow power to the pin you need if its tests for a trailer don't indicate a trailer is connected. Apparently it tests the turn signal circuits to see if there's a load there. (And note it doesn't permit 12V to the plug unless the truck's running-- not just switched on).

2- in something like the 2011-2014 timeframe, F150 owners needed to install a relay and fuse to get the trailer-connector operational. This video describes (and there are part numbers in comments).

As to cutting off the plug, I'd probably buy an additional Attwood connector and make up a 7-pin-to-Attwood adapter instead of cutting (but of course cutting off the plug could work). In any case, please note that wire colors could get confusing. The wire colors of an Attwood plug are not the same as the truck or camper wiring its connected to.

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