Mine did to, but back then it was a option called the Trailer Tow Pkg with a list price of $190. The Trailer Tow Pkg was nothing more than wiring and fuses and relays to provide a 7-wire trailer plug at the back of the truck. Doesn't sound like much for $190. The pkg didn't even include the 7-pin plug. Just naked wires at the rear bumper. But it did include the plug under the dash where you plug in the trailer brake controller. It did not include the receiver, which was another $150 option, or the trailer tow mirrors which cost me another $155.My truck came with the Trailer Tow wiring kit, which included the two relays (trailer battery charge and trailer backup lights), and the appropriate fuses to go along with them.
Look for a sheet metal bracket inboard of the underhood fuse box. It's about 1" wide with a square hole that the relay block snaps on to. If you have the bracket, but not the relay block, then maybe your truck didn't come with them. There's a similar bracket in front of the fuse box that would be for the ESOF relays.I have a 99 f-350 cab & chassis and have all the wires at the back but also can't find relay #38 & #39. Did you find them somewhere else?
Correct. Those go into the cab, but you wouldn't need to go into the cab for trailer wiring. If you don't have factory relays, mount aftermarket ones under the hood and run your wiring under the truck. The trailer battery charge relay just gets activated by a key-on powered circuit (isolates the trailer battery if the engine isn't running), and the backup light relay gets activated by the truck's backup light circuit. You could actually install that back by the rear and tap into the backup light circuit to activate it.I believe these trucks have four firewall pass-through wires in the location you’re describing for up-fitting
Are you sure those guys aren't Ford in disguise?I found the plastic shell at CET1229F. The terminals are TERM225 & TERM221 but for $60+, I will cut the wire.