If your hitch ball is too low, say lower then level it can cause this to happen. Your surge has a hard time, becuase it constantly wants to push toward your truck due to gravity toward your vehicle being lower than your boat trailer. I have the truck hitch level or slightly (barely) taller then the boat trailer. Check your electrical connections on both ends. (Truck and Trailer). Does this happen with a different tow vehicle? You can always lock your surge brakes out with the trailer brake key if they gave your one when you bought your boat. Thit stops the brakes from working.
This is what it looks like.
You can call your trailer manufacture and have them send you one. They sent me one for free. Extreme is the model of my trailer.