2006 EZ Loader trailer surge brake issues

[javincent]

Got a 2006 ez loader trailer with surge brakes. The master cylinder was empty so I added fluid and attempted to bleed them. Took it out fishing and towed it about 90 miles round trip. Had no issues loading the boat. When I got back home and attempted to back it in the shop, I could not back it up due to the brakes not unlocking while in reverse. Put a key to override the brakes so I could put it in the shop. Do the brakes need to be bled more or is there something else I could do. Never had this issue until I tried to repair the brakes (I’m the second owner). Thanks.

[H-D Dad]

If you have a 5 way flat connector on the trailer side, the blue wire should go to the reverse lights on the truck side. Good luck.

[CatFan]

Good news, bad news.

Good news is you fixed the brakes by filling and bleeding them.

Bad news is your solenoid isn’t activating to disable them when you go to back up.

Check that you have power on the blue wire when the truck is in reverse.

There is likely a fuse under the hood dedicated to trailer backup lights that feeds that circuit. IIRC, some trucks didn’t have the fuse installed from the factory. It’s also a common one to blow.

[javincent]

I have a 7 way plug on my boat. The truck backed up fine at the boat ramp and when I backed up to the shop door. When I got out to open the door that’s when they locked up and wouldn’t release.

[bpicinc]

Check that you have power on the blue wire to the solenoid when the truck is in reverse. Also check the ground wire to the solenoid.

[Bill Reynolds]

I have a 7 way plug on my boat. The truck backed up fine at the boat ramp and when I backed up to the shop door. When I got out to open the door that’s when they locked up and wouldn’t release.

The brakes are actuated by the ball coupler sliding back in the housing and compressing the brake master cylinder. It takes reasonable resistance such as backing up a hill or the wheels against a bump to cause the coupler to slide far enough to actuate the brakes. Placing the pin in the coupler prevents it sliding and actuating the brakes so you can back up hill. To avoid this manual operation, the boat’s brake system has a cut out solenoid that is actuated by the truck’s electrical system.
The brake cut out solenoid mounts directly to the back of the master cylinder and and blocks fluid flow to the brake pads when actuated. On a boat trailer wiring harness, this solenoid is actuated by the blue wire which is powered up when the truck is placed in reverse.
The next step is to check for power on the truck connector. This schematic should be helpful.



Edit: I need to clear up some confusion from the above pic.
The reverse light wire from the truck is purple as shown on the pic but the reverse wire/brake solenoid wire in the trailer wiring harness is blue. My trailer plug is a 5 pin flat plug and I have an adapter on my truck from the 7 pin round to the 5 pin flat. This adapter connects the purple wire on the truck to the blue wire on the trailer. I assume all 7 to 5 pin adapters do this whether the trailer plug is flat or round.