Trailer brake help

Burningtire

Burningtire

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Apr 11, 2012
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598
So none of my brakes on my trailer have been working for sometime. I'm stumped on why. When im coasting in neutral and hold down the button on the controller nothing happens. I recently pulled all the drums off and re packed the bearings. All shoes look in excellent condition and everything seems to be moving as it should. I'm not sure how many volts should be at the brakes when at full power but im only getting 8.5v. Doesn't seem to be enough.

With no plug plugged into the back of the truck i have 14.1v on the electric brake pin. When there is a plug plugged in and i pull it apart to check voltage on the opposite side there's 11.9V. There is 9.4v up where it connects to the break away. And like i said i have 8.5v at each brake. This is at full power on the brakes (99%). The brakes make a humming noise like there working but nothing works.

If i understand correctly when you hold down the button on the controller all tires should lock up. Also i have hooked up to other trailers and everything works as it should. Any help is appreciated.
 
Sounds like you have too small of wiring or a ground issue with that trailer. I just fought a similar issue with a new to me trailer, ended up just plugging it in and not hooking up did not provide enough ground to actuate the brakes enough.
 
I rebuilt the whole trailer two years ago. Bought the wire from etrailer, so don't thing the wire is the wrong size. Also i don't believe its a ground issue because i took a set of jumper cables and hooked them to the frame of my truck and to the frame of the trailer. Just not sure where to even start
 
Even with jumper cables it still was not enough for mine to work without it being hooked up, FYI. Pull a hub and make sure that the inside of the drum is not rusty, if it is you will have to clean them up, the magnets can not make contact and work properly if rusty.
 
With your voltage measurements it sounds like you have bad grounds at the brake mechanisms, possibly through rust or paint or something else unknown. But you are experiencing a serious voltage drop that is causing you to loose nearly half the voltage. I would expect no more than about 1.5 volts of drop or loss through wires and connectors and you are reading 5.6 volts drop!!!! That is A LOT!!!! Find that problem and I bet your solenoids will fire fine and actuate your brakes as expected.

Also since you said everything works with another trailer, that further reinforces the idea that the problem is in your trailer...
 
Inside of drums are not rusty. Just cleaned everything and put it back together yesterday. So even if im reading a 5v drop 5ft from the connector on the truck does that mean its within that 5ft? Or could it be anywhere? Ill check the grounds on each brake tonight. I just re did the main ground on the trailer. New connector and what not.
 
Could it be your brake controller itself? Does the brakes work if you pull a different trailer? Just a thought
 
I would bet a ground issue. 9/10 times with trailer lights and trailer brakes grounds are at fault mainly because it is the most overlooked and under appreciated portion of dealing with electronics.

You can test the brake solenoids themselves too. Put one wire to ground and the other to power and hold a screwdriver near it. It should pull the screwdriver to it with enough force you can move the solenoid.
 
There is a chance your truck and trailer plug aren't making proper connection. Even with new ones they need a little bit of "break in" time. With full 12V on a magnet it'll hold a 1-1/4" wrench. Start at the front of the trailer and work your way back.

Kronic
 
So i spent all last night working on it. When i rebuilt the whole trailer 2 years ago i bought all new brake. The whole assembly and each says left and right. But when i installed them i didnt know it was left or right if you were sitting in the drivers seat. So long story short i put the brakes on the wrong side. Also one of the arms the magnet is connected to was froze up. Still doesnt explain the huge voltage drop but once i get these figured out ill work on that later. But i did check the resistance on two of the magnets and they were within spec and when power was applied the screwdriver would stick right to it.
 
One thing I learned from being a electronics tech in the Navy, whatever you screwed with last is usually were the problem is. Sounds like you found it.
 
Well hopefully once i get these brake assemblies on the right sides i can further investigate if they still dont work.
 
Got the brakes all switched around. Cleaned all grounds, and checked resistance on each magnet. All are within spec. Re adjusted them and still nothing. With brakes at full it still acks like nothing is even there.
 
What gauge is your wire? How far is it from tongue to axle? Did you use those little blue "scotch-lock" pieces of crap? Do the grounds go all the way back up through the trailer plug to the truck ground or did you just ground them to the frame?

The answers to these questions will lead you to the answer. And just because you bought the wire from some trailer place doesn't mean it is large enough. Trailer with crappy wires is what you get when you let a place that welds trailers do electrical engineering work. $.02

If you ground the brakes to the frame, you are begging for trouble. They need to be connected to a ground wire and ran up through the plug to the truck ground.
 
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The largest wire in the loom should be the brake wire, no matter what, learned that one the hard way. Keep in mind that you can buy 7 wire with many different options for internal wire size.

When I rewire I ground at each connection, through the trailer, and through the wiring harness back to the truck. One bad ground can cause you to spend entirely too much time trying to fix a problem that you can not find.
 
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A lot of folks think #16 and #14 awg are large enough for brakes....neither is large enough. I simply googled this and found a etrailer questions. I always run #10 and this kinda backs that up. The axle manufacturer for your brand will also have a suggestion depending on trailer length. #12 AWG minimum would be my guess.

http://www.etrailer.com/question-30111.html

DON'T use scotch locks. Use butt splices with a good set of crimpers and then wrap with heat shrink or tape. If you have any scotch locks....put them all back in the bag....and burn them.
 
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4x4dually said:
What gauge is your wire? How far is it from tongue to axle? Did you use those little blue "scotch-lock" pieces of crap? Do the grounds go all the way back up through the trailer plug to the truck ground or did you just ground them to the frame?

The answers to these questions will lead you to the answer. And just because you bought the wire from some trailer place doesn't mean it is large enough. Trailer with crappy wires is what you get when you let a place that welds trailers do electrical engineering work. $.02

If you ground the brakes to the frame, you are begging for trouble. They need to be connected to a ground wire and ran up through the plug to the truck ground.
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Im not exactly sure on the gauge wire for the main harness that runs from the front to the back. I would guess 12? but im not sure. The way i have my wires ran is, I run the whole harness all the way to the back of the trailer then i have everything t'd out of there. Then I have 2 12 gauge wires running to the brakes. One for left side and one for right side. Id say its 25ft to the back and then another 5ft back to the brakes. Main ground is grounded to the frame and each magnet is grounded to the frame. Ill see if i can dig up the info when i bought the wires.
 
My advice is to not use the frame as a conductor. Bring the grounds out of the magnets and tee them together and run them in a wire to the front and through the plug. I typically bring all grounds from every light to the front and ground under one big ass bolt with large lugs. That way each light and magnet has a copper path to the truck and doesn't rely on steel. Put the hot to all your magnets on one of your 12 awgs. Use the other for all the grounds. I've never heard or seen anyone splitting left from right. You might get different voltages that way and cause a problem. If you lose one wire or develop a bad connection, you may lock one side and not the other and cause an accident. $.02
 
I assume the trailer does not have a safety disconnect cable and battery correct?
 
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