[coloradofitness]

I noticed earlier postings regarding electric trailer brakes, and now have my own dilemma. When I touch the brakes in the F350 truck which pulls our trailer (has four electric brake hubs, and a 7 pin connector), the left set of tires completely locks up (skids), while the right set of tires works fine. It had been just one wheel locking up, but in the process of trying to fix it, I seem to have made it worse. I can disconnect the sets of brakes that lock up, and the other side will still work fine. The wiring to the trailer seems to work fine (lights, brake lights, blinkers, etc). And there is obviously electricity getting through to all the individual braking units. This was not always a problem, and nothing obvious has occurred to understand why it started working this way. All help is appreciated.

[leroys1000]

If it is just one brake,it may just need to be adjusted.
Should be adjusted to where the shoes just touch the drum.
Should be a manual adjustment on each wheel.
Also make sure the wiring hasn't shorted to the frame anywhere.

[coloradofitness]

Thanks for your fast reply.

I think I understand what you're saying. But since the brake controller is only sending one signal (perhaps full strength instead of being "resisted") why wouldn't all four brakes lock up, not just one or two?

[leroys1000]

Yeah,that's why I changed my reply.
If it was actually both brakes on one side,it could
be the controller has independent resistive tracks
inside for each side and one side has worn down.
It may be that there is actually two signals being sent
from that particular controller.
One for each side.
But you were saying that it was one brake,so I would
check the adjuster for that wheel.

[coloradofitness]

Many thanks for your assistance. I might have another brake controller to hook up and test, and I can adjust the brakes as well. I appreciate your explanation of what could be happening inside the brake controller. I've always wanted to be better at electronics.

[leroys1000]

Yeah,I know what you mean.
I've been taking stuff apart since I was a kid.

[K7M]

I doubt it's the brake controller. I would adjust all four wheels. How old is the trailer and who makes the axles. If it is new and they are dexter, pull a wheel and get the backing plate # and call Dexter, they had a problem with their auto adjust axles locking up. If it more that a year old and has considerable use, jack it up, pull the brake away cable , or have someone hold the brake actuator lever for full brakes and test each wheel for adjustment. To check the adjustment, with the brakes full on, try turning the wheel forward and backward. You should get no more than from "12 oclock" to "11 oclock" one way and to "1 oclock" the other way. If you have more than that adjust the brakes. Also look for leaking grease as grease and oil will cause lock up on a wheel. If the adjustment is OK then pull each wheel and inspect the brake magnets for excessive wear and bare copper on the face as this will also cause either brake failure or excessive braking.

[coloradofitness]

Thanks for your advice.
Before I read your reply, here's what I found out today.
Its not the brake controller, as I bought a new one and it does the same thing. The "same thing" being this: When the brake pedal in the truck is pressed, or the brake controller itself "pressed" only the two driver's side brakes come on and I can't turn the wheel. Neither of the magnets on the passenger's side are getting energized. If I hook direct current straight to the magnets on the passenger side they work, and the brake holds. I think this is telling me I have a short somewhere between the driver's side brakes and the passenger side brakes. However, most of the wiring is very inconveniently inaccessible because its in the frame tubing, etc. I can't really even trace where it all joins, and splits. Maybe I can use an ohmmeter to see if there's resistance between one side and the other?
Thanks for your continued help.

[leroys1000]

Sounds more like there is a break in the wiring somewhere.
If there was a short,you would probably be seeing smoke somewhere
or be blowing fuses.
Might start by checking for missing pins in the connector between the
vehicle and the trailer and possibly broken wires inside the connector.
Then see if you are getting voltage at the connector on the vehicle.
If your good there,then you have a break between the trailer connector
and the brakes.

[K7M]

Ok usually the brake wires come down the drivers side, and go through the axle tube to the passenger side. It is very common for the wire in the tube to wear and short or disconnect. The easiest way is to just cut the old wire out and run a new wire from left to right across each axle to the opposite side. Just run the new wire across the top of the tube and use zip ties every 6 inches or so to secure the wire in place. I would use 14 ga. wire as each magnet draws 1.5 to 2 amps each and if the wire is too small the right hand side will have more braking power than the left. Make sure you completely disconnect the old wires as they could short and leave you without brakes.

[coloradofitness]

K7M and leroys1000
You read my mind. I was going to run wire from the side where the brakes work, under the trailer, and connect to the side that doesn't work. Will post when I get a chance to do this tomorrow. Thanks for the suggestions.

[K7M]

If you go to the frame make sure you leave enough slack for up & down movement of the axle.