For the iRV stereo part # 292-101809 the yellow wire runs to the vehicle battery, the red runs to a circuit that sees voltage only when the vehicle is turned on (think of this as the activation circuit to turn it on), blue runs typically to a power antenna to tell it to activate (can also be used to activate an amp), and black is ground.
If you do not have a power antenna or any other circuit that you need to also be powered on when the key is on you can leave the blue wire disconnected. view full answer...
If you do not have a factory hitch on your 2018 Ford F-150, I recommend the Curt Trailer Hitch Receiver - Custom Fit - 2" # C86HR. Not only does this hitch come with a 6,000 pound towing capacity and a 900 pound maximum tongue weight, it also comes with a superior gloss outer coating over the base coat that will provide more resistance against rust and corrosion that Draw-Tite and etrailer alternatives. Also, the installation includes a bolt-on process that only takes about 40 minutes to... view full answer...