- is very specific to boat trailers with disc brakes
As your vehicle begins to slow, the weight of the trailer moves forward. When this happens the actuator on the trailer compresses and pressurizes the hydraulic fluid in the brake lines and causes the calipers to apply pressure against the rotors causing the speed of the trailer to reduce. The actuator doesn’t know the difference between compression from forward motion and backward. Therefore, when backing up a hill the actuator will apply the same pressure and engage the brakes.
A 5 flat connector allows for a 5th function to the trailer. It is activated by your reverse lights when your tow vehicle is placed in reverse. The power is sent to a back-up release which disengages the brakes so you can back up the hill without the brakes applying.