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Trailer Brake Issues

Discussion in 'Trucks and Trailers' started by matthew horner, Jun 19, 2006.

  1. matthew horner

    matthew horner LawnSite Senior Member
    Messages: 696

    I have a little problem I'd love some advice on.

    My brakes were working fine Thursday. Friday, all of the sudden, the brakes are weak to not working AND the light on the brake controller is very dim. I looked in the manual and it says that the weak light is a symptom of a bad ground or a disconnect in the trailer circuit. I gave everything a once over, checking from wire to wire, and it all looks fine.
    Any ideas? Anybody had this experience before?

    Thanks so much,
  2. matthew horner

    matthew horner LawnSite Senior Member
    Messages: 696

    The light only dims when I press the pedal AND the trailer is plugged into the vehicle harness. So I'm assuming that the problem is in the trailer somewhere. Are there two or one wires going to each drum? Also, if I put a voltmeter on them at full braking, what should I be reading? I may just rewire from the harness back to each drum. Do they tie in to the trailer ground?
  3. matthew horner

    matthew horner LawnSite Senior Member
    Messages: 696

    Still diagnosing this.
    It appears that per each drum there is a ground and a hot wire. Can I put a battery on the hot wire and ground the ground and expect it to brake?
  4. firecapt13

    firecapt13 LawnSite Member
    from NC
    Messages: 96

    sounds like a ground problem to me
  5. matthew horner

    matthew horner LawnSite Senior Member
    Messages: 696

    As in the ground is not grounded, or the hot wire is grounded somewhere?

    The lights all work fine.
  6. TLS

    TLS LawnSite Fanatic
    Messages: 7,943

    Does your trailer plug have a ground in it? Or are you depending on your ball mount to ground through?
  7. matthew horner

    matthew horner LawnSite Senior Member
    Messages: 696

    No, the trailer plug has a ground in it.
  8. Tharrell

    Tharrell LawnSite Silver Member
    Messages: 2,967

    I don't really know much about this specific question but, it sounds to me like a ground problem. I do know you can have a "weak" ground. A weak ground wire from the battery of my truck caused fuel pump, and computer problems in my truck.
  9. TLS

    TLS LawnSite Fanatic
    Messages: 7,943

    Also, make sure your brake wires aren't run INSIDE the axle tube. They chaff and will wear through and ground the brake wire causing all sorts of havoc.

    I run mine OUSTIDE the tube.
  10. Audrey

    Audrey LawnSite Senior Member
    from Pa.
    Messages: 570

    I use an RV plug with my trailer. What I have found is those 7 little tabs will corrode from time to time. Acid rain is great!

    I take a very small flat file (or a screwdriver) and wrap a piece of emery cloth around the tip length wise. That will get you in there to rub the corrosion off. Blow it out, then use some electrical contact cleaner to finish up. Do the same to the plug also. That usually does it for me. I have a full size battery on my trailer and sometimes that corrodes. Also check your main ground to the trailer itself. Every so often I need to clean those, or replace them.


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