Running 12V Power When Installing 4-Way To 7-Way Adapter On 2015 Ford F-150 With Factory 4-Way

Question:

It’s my understanding that up to the year 2014, on Ford F150 Trucks that are not tow-ready, that you’ll have to install a Relay and Fuse in fuse box slots number 9 and 21 in order to splice directly to the trucks 12v wire and get 12v power to pin #4 on your 7-way adapter, part #37185. My question is: If this is the case, I want to be able to do the same thing on a Ford F150, but model year 2015, but it’s also my understanding that you DO NOT have to have the Relay and Fuse in place on a 2015 model in order to get the same results as the application explained above? My truck only has a 4-way, and I’m converting to 7-way, but I do not want to hard-wire it directly to the battery in order to achieve this. I want to be able to splice into the existing power wire located near the back bumper before it’s down-sized to a 4-way, but I keep reading conflicting information about whether or not the Relay and Fuse is needed on a 2015 model. Photo attached shows my actual wiring, I believe my battery charger 14v is the Blue thick-gauged wire, and my manual shows slots 9 and 21 as not used. I supposed I can also test the wire to see if theres power?

asked by: Norm

Expert Reply:

If you have a factory 4-way trailer connector at the back of your F-150, the 12V power wire to the connector should be either red or orange and will be a thicker gauge. The blue wire is typically the brake wire. I recommend using a circuit tester like part # PTW2993 to test each of the wires for function before splicing into them. Have someone sit in the driver seat and run through the functions while you test. If you find the orange wire is the 12V power, it does not need a fuse or breaker because the truck will already have it installed.

I have attached a photo of the # 37185 that shows where the wires should be run.

expert reply by: Jeffrey L