Help with electric brakes

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  #1  
Old 06-06-10, 01:46 PM
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Help with electric brakes

Hi everyone, new here and also a first time camper owner.

I have a '87 24' camper with tandem axle, electric brakes. I've done a bit of reading and from what I can gather, the brakes on the trailer are not working at all.

At first I thought something was wrong with the magnets but I took the wires from one of the magnets and hooked them to a 12 volt battery just briefly. I assume the magnet worked fine because a screw driver stuck to it. Now, I tested the voltage coming out of the vehicle plug and have a little over 13 volts coming out of the brake plug. However, I tested the wires back at the hub that were attached to the magnet, and am only getting .04 volts. I'm going to go out on a limb and guess that that's not enough voltage to run the brakes??
What should I be looking for to correct this or what other type of testing could I do to pinpoint my problem? I just bought the camper and the guy said that everything worked, but then again, he's had it just sitting stored in a barn for 2 years now.

Would be very grateful for any assistance with this as I would like to get this fixed. Oh, and also, the guy said he has never even hooked up the breakaway switch, let alone use it.
 
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  #2  
Old 06-06-10, 08:40 PM
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First check the voltage coming out of the brake control. Then back at the outlet to the trailer plug in. If that is around the 13 to 14 volts the problem is in the wiring/plug going back to the brakes. If the breakway switch isn't in the circuit at all, meaning no wiring going from the brake circuit to it and no break in the circuit designed for it, the problem is in the wiring going back or the male plug on the trailer. The terminals in the plug could just be corroded. Sometimes people pull out the plug by the wires instead of holding onto the plug. That tears loose the wires from inside the plug.

Probably 3/4 of the time the problem is in the grounding of the brakes, but it sounds like you aren't getting anything back to them.
 
  #3  
Old 06-07-10, 05:05 AM
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thanks for the reply marbobj

The breakaway switch is in the circuit, wired in and everything, he just said that he's never bothered connecting it to his truck or using it. If that's the case, could this breakaway switch be interrupting the voltage going back to the brakes by being corroded or even faulty? I do have 13 volts coming out of both the controller and the plug on the truck. Somewhere along the line I'm losing that voltage before it gets to the brakes.


I'll start by checking at the plug of the camper later today when I am done work.
 
  #4  
Old 06-10-10, 06:23 PM
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Follow wires back to (usually Left Front- drivers side ) backing plate, and start testing there for 12 volts. If you can plug the trailer in, and test your front plug (7 pin) you should have a live terminal there.(12volt+) Use a jumper across from that to your brake wire terminal in the plug and that will eliminate the need temporarily for a battery. (I'm assuming you know by now which terminal is the brake feed.) Normally the main feed for brakes goes down the frame to the drivers front wheel, then across to other side through axle tube, or on outside of it. Then from there to rears, or in some cases, it will go to rears at same spot as where it joins to go across to other side. Anyway, find that main wire(s) + and - going back, and check it at first connection for 12 volts, or just ahead of it. Then go from there. If no 12 volts there, work back toward tongue of trailer. I use a test light and just poke wire to see if I have voltage. If all the way to tongue, and no 12 volts, check plug. If you do have 12 volts to first wheel, and it has those stupid scotch clips connecting wires, cut them out of there and get rid of them. Then re-join (twist together) wires temporarily and see if voltage isn't better. Just watch the + doesn't touch metal or (-) other wire. If in doubt, just wrap with electrical tape for now. Once you get 12 volts there, go to next connector (other side usually) then on from there and do same at each one until you get good voltage, or if necessary, replace broken or shorted wire(s). I say wire because we buy it in a shielded cable with 2 wires inside (white- (ground) and black (+). Don't play with replacing 1 piece of wire if there is a break or short in it, replace both positive and negative. Once all the wheels have 12 volts, then you can start checking that all magnets work properly and shoes etc are moving as they should. Also, if your breakaway switch is hooked up to a battery and working properly, when you pull the pin, all 4 wheels should have 12 volts. Another good way to keep current to brakes while testing. Once you have all connections good and ready, use solder, butt connectors and shrink tube or whatever, but don't use those stupid scotch clips, they are the worst thing to use on connections where moisture can get to them, and have caused more electrical problems over the years than I can count. Only if necessary for use inside where it's dry.
 
  #5  
Old 06-10-10, 09:40 PM
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Originally Posted by Mike.B View Post
I use a test light and just poke wire to see if I have voltage. .
Don't ever poke thru the insulation of a wire with a test light... The little hole you just created is the perfect spot for moisture, salt, etc to get inside the wire & corrode it... If you have problems in the future,, it'll be @ the areas you poked the holes in the insulation.... Guaranteed... Roger
 
  #6  
Old 06-13-10, 06:47 AM
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Originally Posted by hopkinsr2 View Post
Don't ever poke thru the insulation of a wire with a test light... The little hole you just created is the perfect spot for moisture, salt, etc to get inside the wire & corrode it... If you have problems in the future,, it'll be @ the areas you poked the holes in the insulation.... Guaranteed... Roger
If you rip the insulation wide open due to slipping off the wire, yes I agree , a little brush-on liquid tape or similar after is a smart move, but a test light with a good sharp point shouldn't be a problem.The trick is to hit it dead center. Been doing it for 40 years on cars and RV's, and never had one come back to haunt me. Maybe I'm just lucky?
 
  #7  
Old 06-17-10, 08:22 AM
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trailer brakes

Also make sure you have a good ground between the trailer and towing vehicle. Some folks thinks the hitch will do it but it wont.
 
  #8  
Old 06-19-10, 01:47 AM
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Sorry haven't got back to this sooner but it's been hectic here.

Anyway, although I'm still learning all about this electric brake stuff, something just didn't seem right to me. If I applied 12volt power from a battery to the trailer plug itself, I could get all 4 wheels to lock up and work fine. Once I went and hooked it to the truck and applied the brakes, or manually slid the controller, nothing would happen.

I went and talked to the mechanic that installed and wired in the controller and everything in the truck and he asked me to bring both the truck and the trailer to his shop. Well, to make a long story short, after 4 hours of checking, it turned out that the 12volt power source he had picked to wire the controller too, was what was causing the problems. When we applied the brakes, it was making my 4 ways and flasher relay?? in the dash go nuts and wasn't running the controller properly. Hooked it to a different 12volt power source and it worked perfectly after that. He said he's never had that happen before and the wire he used the first time was the one that my truck schematics showed to use.

But, now the brakes work great and while I was repacking the bearings, I noticed that 3 of the magnets were quite worn on the bottom half of them, and the hubs on them same 3 wheels had some pretty nice ridges/gouges in them, so I replaced all 3 magnets and hubs.

Thanks for all your replies and help. Learned a lot just in this little bit!!
 
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