Truck seems very labored when backing up trailer

[BoostnLLY]

Today I pulled a 24’ sea ray back to my
House to clean it up for vacation. (This is my first time towing this boat and using this truck to tow this boat also.) as I was backing up the trailer, it seems like almost like the trailer brakes or something was engaged and felt like it took a lot of power to get the boat to move backwards. The rear tires to the boat were not dragging.

I knew something felt weird instantly so I put the truck in drive and the truck and trailer moved smoothly forward, then I put the truck back in reverse and it started moving smoothly then felt like it locked up again. This happened multiple times. It took a lot of power to move the trailer in reverse, it was raining and as I was backing into my driveway with about a 20 degree slope, I had to put it in 4 wheel drive to stop the rear tires from spinning.

Typically I drive a 6 x 10 utility trailer and I’ve never experienced this before. Is the boat really that heavy? I did just put on brand new nitto grapplers 305x20 two days ago, could they be rubbing? Is my trailer brake booster on the truck malfunctioning?

I’m baffled

 

[BoostnLLY]

I think I might have a bad brake controller. Going to have to test tomorrow although I’ve never experienced this on my utility trailer

 

[2004LB7]

Have you tried it with the trailer unplugged from the truck?

 

[fl0w3n]

Boats are usually not electric brakes, at least the ones I’ve dealt with. It’s probably surge brakes, and the incline and reverse was triggering them. There’s supposed to be a wire that disables them when you put the truck in reverse. Our boat recently started acting up and was doing the same thing. I was lazy and didn’t diagnose, just tried to avoid backing up lol

 

[Chevy1925]

Been a long time since I messed with a boat trailer but isn’t there a lever you flip back by the tongue too that locks out the surge brakes?

 

[2004LB7]

The few boat trailers I've dealt with where electric brakes. Generators on the other hand where all surge along with all equipment and trailers I've rented from united rentals and sunbelt. Surge sucks but does have its place for people who are not very trailer savvy and that's why equipment rental places use them. Oddly none had any way to disable the brakes for backing up. You just had to muscle through it

 

[BoostnLLY]

I’m going to try disconnecting the 5 flat trailer plugs first. The trailer has what I’ve always thought was called, a “brake away” cable that activates if the trailer disconnects... here’s a picture of the tongue.

Edit: just learned the surge actuator is under the tongue and looks to me that it was definitely engaging with the incline.

 

[RMJ_LB7]

Boat trailers engage the brakes when going in reverse since the actuator is actually on the tongue. I am not positive on how to bypass it but I can ask my service department if you would like?

 

[darkness]

With a 5 blade plug the 5th wire should be your reverse lockout. There will be a solenoid that closes to keep the brake fluid from flowing out of the master cylinder. Either diagnose that solenoid or you’ll have to block the surge brake from sliding when backing.

 

[BoostnLLY]

Let me look at my trailer plug adapter. Thanks guys

 

[Pure Diesel]

With a 5 blade plug the 5th wire should be your reverse lockout. There will be a solenoid that closes to keep the brake fluid from flowing out of the master cylinder. Either diagnose that solenoid or you’ll have to block the surge brake from sliding when backing.

When I converted, my old boat trailer, to disc brakes from drums the kit came with this feature.

https://www.etrailer.com/s.aspx?qry=Backup+Solenoid&furl=-pg-Accessories_and_Parts

 

[BoostnLLY]

Thanks Guys. It was a defective 5 Prong Trailer Plug That was newer.

 

[Pure Diesel]

Glad you got it figured out.

 

[trashygasman]

I have my 5 flat plugged into a 7 round adapter. The center pin on the 7 had gotten pushed in and wasn’t making contact causing it not to lockout the reverse solenoid on my boat. Took me a while before I actually took the time to figure out what is was. I would just put my truck in 4wd and slide the tires. Lol

 

[2004LB7]

Good info here. I'll have to log this in the back of my head for if I ever encounter this. So far I've yet to see any surge brakes with this feature

 

[Pure Diesel]

With my current boat/trailer, I have drum brakes and backing up isn't a problem even without the lockout solenoid. When I went to disc brakes is when the backing up was problem.