Crazy Wiring Problem....Please HELP!!!

Discussion in 'Boats and Motors' started by OSU_Fisherman, Aug 25, 2007.

  1. OSU_Fisherman

    OSU_Fisherman Bassin' Buckeye

    Alright, my dad and I are totally stumped on this one. The trailer that I rewired is not working correctly on my truck, but it works fine on my dads. When the trailer is hooked up to my truck the running lights work, but as soon as you put the brake on, the lights go off instead of getting brighter.

    When the trailer is on my dad's truck everything works how it is supposed to.

    The wiring that comes off of the trailer goes into a 4-pin connector and then goes to an adapter to fit in my 7 plug hitch. To check and see if it was my truck wiring we checked the current coming out of the adapter. Everything checked out on my truck and my dad's. That is why this is so confusing. Any suggestions would be appreciated.
  2. EE


    probably no help here, but did you recently re-wire the 4 pin plug at the end of the trailer? There are tons of those and it's possible you wired on a different one than what is required.
    Is it possible you are using an incorrect adapter (the 7 pin one)?
    I had a similar issue and resolved it with one of those 7 pin things, but I had to look for a bit - there seemed to be a couple of different kinds of receiving adapters.
    It's probably not much help here, but if everything works well on your dads truck, and on your truck the brake lights turn off instead of on (when depressed), I'm guessing the problem is somewhere in the adapter (where the trailer wiring hitches to your truck).

    If not, I guess you're dad will be towing for a while! :D

  3. misfit

    misfit MOD SQUAD

    test all wires on each side of connector to see that they correspond.i've seen that problem before.can't remember exactly what it was,but it's possible the brake and tailligt wires are crossed up.brake light wire from truck could be tied into taillight wire on trailer.
  4. Champion188 Elite

    Champion188 Elite Smallie slayer

    Check for bad ground on your truck!
  5. DaleM

    DaleM Original OGF Staff Member

    Run a ground from the trailor ( make this an extra wire) the do the same on your truck. I had the same problem and after I ran an extra ground wire as described above it worked fine. The later model vehicles seem to have this problem.
  6. +1 on the ground that would be the first place I would look.
  7. do one of you have amber rear turn signals on your truck? They take a special adapter to make them work.....
  8. I would have to agree that it sounds like a ground problem!!
  9. OSU_Fisherman

    OSU_Fisherman Bassin' Buckeye

    I figured that it was a ground problem too. So, I re-wired the plug (4-pin) and then cleaned out the adapter and reciever with electrical parts cleaner. Still didn't work.

    So, I went under my truck and looked at the ground from the reciever and it looked real solid. But, just to take out all variables I decided to redo it. Bolt and connector were so rusted to the frame I couldn't get either off. So, after a new screw and connector.....THE TRAILER WORKED GREAT!!!

    Thanks for the help!!!
  10. Hetfieldinn

    Hetfieldinn Staff Member

    Put some electrical grease on the new frame/ground connection, and also rub some on the connector prongs.