Trailer running lights and brakes wont work?

Discussion in 'Trucks and Trailers' started by RedWingsDet, Dec 28, 2006.

  1. RedWingsDet

    RedWingsDet LawnSite Gold Member
    from Detroit
    Messages: 3,556

    I have a 2005 Enclosed 20ft Haulmark. The Lights on the inside, and outside lights wont work, however the tail lights work and so do the flashers and turn signals. Also, the brakes wont work and they are NOT registering on the contoller. and the breakaway isnt working.... One week its working, and the next week it wasnt.

    Any idea what causes this? Do I need to re-wire the entire trailer?

    Thank You.
  2. KS_Grasscutter

    KS_Grasscutter LawnSite Gold Member
    Messages: 3,335

    Check the trailer light fuse on your truck. If it is blown, you probably have a short somewhere. It is likely on the trailer. I know I had a similar problem on my trailer this summer, but finally fixed it. It was a wire that the insulation rubbed through and was touching the trailer frame.
  3. RedWingsDet

    RedWingsDet LawnSite Gold Member
    from Detroit
    Messages: 3,556

    well sometimes the lights do come on, and sometimes not. so I wouldnt think it'd be a fuse. Im thinking it'll be hard to find where the wire would be touching the frame, since its an enclosed. It might be eaiser to run all new wires?
  4. LindblomRJ

    LindblomRJ LawnSite Silver Member
    Messages: 2,570

    I am thinking it might be a ground problem. Or a short of some sort.
    Okay I will ask 20 quetions:

    What type of tow vehicle?
    What type of plug? What conditon is it in? Thinking about 6round or 7 pin and the inside of the plugs.

    Have you checked, with a test light or meter the plug on the tow vehicle?
    How is the condition of the gound on the tow vehicle, and on the trailer? Good metal to metal contact?
    How about the connections at each of the lights and brakes.

    It sounds like it is difficult to acertain the overall conditon of the trailer lights.

    Most trailers from the factory seem to be wired fairly cheaply. If you do need to re-wire the trailer make certain that you use good quality wire with a good jacket.
  5. Dstosh

    Dstosh LawnSite Senior Member
    Messages: 716

    I have had that happen also. It is most likely the culpret. Do you need to rewire? No probably not, but it will be a joy trying to find the short.
  6. muddstopper

    muddstopper LawnSite Silver Member
    Messages: 2,341

    Check the tow vehicles receptical first to make sure its the trailer and not the truck. If the Pins are dirty or corroded, get some battery terminal cleaner and spray on them to get them clean. Then check the ground wire, since your lights seem to be coming and going, the ground might be rusty at the connection and the trailer is having to ground thru the ball and hitch. You should be able to back up to the trailer and just plug in the wires and everything work, if it doesnt, then your ground wire is bad, either on the truck or the trailer. There is no other reason for the trailer wireing to be bad if it is enclosed, unless someone has been fooling with it. Check all connections with a test light and/or meter to make sure you are getting the rquired voltage. Less than 12 volts could also suggest a bad ground. If the wires have a break or are shorting out, you should be blowing fuses, you say you are not so I suspect a bad ground.
  7. HydroCutter

    HydroCutter LawnSite Member
    Messages: 145

    I had similar problem on a dump trailer. It was a ground problem. The bolt holding the dump level was loose, breaking the ground at every bump.

  8. GreenN'Clean

    GreenN'Clean LawnSite Bronze Member
    Messages: 1,512

    I had the same problem this past year and it was a loose wire under my dash board, i found a wire that wasn't taped properly and the wire was loose enough that every time i hit a bump it would short out. It was a cheap fix
  9. LawnTamer

    LawnTamer LawnSite Gold Member
    Messages: 3,986

    On my enclosed, the tail-lights/brakelights run off the truck, but the brakes and the dome lights run off the battery on the trailer- if this is the case on your trailer, I would start by checking the battery terminals for corrosion and then start checking for shorts. If the brakes/lights cut out at the same time then the problem is pretty close to the battery.
  10. LemkeLawns

    LemkeLawns LawnSite Member
    Messages: 81

    Are you relying on the Hitch and Ball to ground the trailer? If not wire a ground through the plug. Its worth a try.

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