Hey all, searched a good bit and couldn't find anything helpful.

I picked up a new boat on Saturday and went through the trailer set up on my 2022 F350 Platinum. All of the lights work, and truck is giving me the no blind spot recognition prompt. When I modify the gain (with 7 way plugged in) it says "no trailer". When i hit the brake controller, it says "trailer disconnected". The trailer has surge brakes so i think they're still activating while driving, but not 100% sure. Anyone have any thoughts? I appreciate it in advance.

 

The surge brakes I had on a trailer before had no electrical connection, it was mechanically operated by the coupler pressing a brake solenoid to apply the hydraulic pressure to operate brakes, there wasn't a need for a 7 pin connection.

 

The truck brake controller recognizes a trailer because of a battery that it is charging on a trailer to activate the brakes when the truck disconnects and the breakaway switch is activated.

 

I second Redford's opinion on the possible bad ground. New trailer, but it could've been left loose, or rusty or even painted over the metal before they connected it.
I had the exact same issue on my truck ('23 F350) where it was fine with two of my trailers but gave me the "trailer disconnected" message whenever I tried to test the brakes on my flatbed equipment trailer. Lights and signals were fine. Turned out to be worn magnets on the trailer brakes. My '19 F250 didn't care and would activate the brakes as expected, but the new truck didn't like it. With your trailer being new, I would think the magnets should be fine, but potential for one or more to be loose or have a wire break leading to it.

 

Surge brakes are mechanical:



When your vehicle slows down, from braking, strong winds, hitting a cow, barreling into soft sand, etc., the inertia of the trailer pushes forward against the hitch. This forward pressure compresses a spring and a hydraulic cylinder between the tongue and the trailer's coupler such that pressure is applied to the hydraulic wheel brakes.

No brake wiring needed, allowed, or possible. Your truck's brake controller would rightly see nothing. The picture above is a U-Haul tongue. How does U-Haul save flat-spotting tires while not requiring every rental to have an electric brake controller? Mechanical surge brake. Same goes for loaded versus unloaded.

Electric brakes apply the same amount of braking on the trailer whether loaded or not because it does not know if the trailer is loaded or not. That's why you have to adjust the controller when towing a cargo trailer of some sort between significantly loaded and empty. Too much power while empty leads to lock-ups while not enough power while loaded leads to poor braking and overworked brakes on the towing vehicle. With surge brakes, this is not a concern. More weight means more inertia to push harder on the hydraulic cylinder. Great deal for U-Haul car carriers etc. Also a great deal for boat trailers. Drivers don't have to adjust a controller after launching only to forget to readjust after loaded up again.

The operational downside of surge brakes? Backing. If you're backing up on hard terrain, either flat or downhill (like boat ramps and boat-trailer parking), no big deal, that's what the spring(s) is/are for. If you are backing through a soft surface or uphill, then the surge brakes will be activated by the inertia of the trailer not wanting to move uphill while the towing vehicle pushes it.