Trailer brakes

[liquidforce133]

Tonight I was backing up my trailer to reposition in the parking slot and the trailer would not back up, as if it had the brakes on. When I got out, I realized it was possibly because we had just pulled the vehicle tow connector out when launching the boat. After I reconnected the tow connector (electrical conection to the vehicle), the trailer reversed no problem and was back to normal. Is there some kind of reverse e-brake that is on when the trailer is not connected to a vehicle to prevent rolling? What else would have caused this? It went away as soon as I connected the plug.

[Stevemo14]

I believe if your trailer Pigtail has 5 prongs, the 5th prong is to deactivate the brakes when you are in reverse.

[jhiestand]

Stevemo14 is correct. If you have disk brakes on your trailer they rely on an electric lockout that is applied when you put your vehicle in reverse (5th pin on your trailer hookup).

[liquidforce133]

So I should not take the plug out when launching? I had heard that leaving it in could damage the lights/electrical when submerged.

[Stevemo14]

You should be able to leave it in. It should be rubber, and the vehicle connection should be too, hence waterproof.

[SatherG230]

I think the "unplug the lights" logic came during the time of incandescent trailer lights and backing a hot bulb into cold water would burn them out or cause corrosion...I have never done it and have not had much of a problem with the old bulbs. Never had a problem with LED.

Your post also reminds me that the only times I have had a problem with the brakes going on in reverse was the first time out in the spring. Taped a socket in the slot to keep the hitch from sliding and activating, but now realize that it is probably due to some oxidation at the truck connection that "fixed" itself with subsequent unplugging / plugging.

[SilentSeven]

Assuming you have hydraulic surge brakes.

Look around your actuator (tongue of the trailer) and you'll likely see something that looks like this - https://www.etrailer.com/Accessories...71-755-00.html

That's the reverse lockout solenoid and its cuts brake fluid pressure to the wheels when actuated. In most wiring setups, it's tied to the reserve light circuit - ie / reverse lights on, actuator kicks in preventing any trailer braking. As others have pointed out, if you pull the wiring plug, this system will not work and reversing on a flat or incline will lock up the brakes.

If you want to pull the plug when launching, make sure the trailer on the down side of the ramp first. Then you can pull the plug as there will be no compression on the actuator to work the brake circuit.

[jhiestand]

So I should not take the plug out when launching? I had heard that leaving it in could damage the lights/electrical when submerged.

Yeah, I remember when this was standard practice as well. It was before disk brakes and sealed lights came into play. Just leave it plugged in and you'll be fine.

[jjackkrash]

I've never unplugged my trailer when launching and have never had any problems associated with not doing so.