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Trailer lights

Discussion in 'Truck & Equipment Repair' started by SnowMatt13, Aug 27, 2009.

  1. SnowMatt13

    SnowMatt13 PlowSite.com Addict
    Messages: 1,533

    I'm usually pretty good with these issues, but this one has me stumped.
    The truck is my father-in-law's 2000 F-250
    There are 2 trailers involved. I know everything on the trailers is good, I hooked both of them up to my truck and tested all the lights.
    We installed a new plug and harness on his truck. I have a tester for trailer lighting and the tester indicates all functions are working. Here is the issue:
    When he is hooked onto his cattle trailer he has running lights (any lights that would be on when the head lights are on), no brake or t-signals.
    When he is hooked to the flat bed, it's opposite, he has brake and t-signals, no running lights.
    Any thoughts?
     
  2. basher

    basher PlowSite Fanatic
    from 19707
    Messages: 8,992

    ground is wrong, I can not tell you how it's wrong but it is the only thing those two functions share.

    Is it (the truck) Factory wired, What do you mean when you say your replaced the plug and harness?
     
  3. have to agree with basher ground would be suspect except when you count both trailers everything works, next the recently installed plug\harness was it new? are the contacts clean? are the trailers making a good connection? are they both 7 6 or 4 pin? are you using a adapter? is it good? Does the truck have a 4 and 7 pin combination plug are you using the same plug for both trailers?

    if the functions that are working are working well with no backfeeding or ground issues(ie running lights work one turn signal dim or one turn signal works other dim) i would really suspect the plugs if the trailer connections aren't the greatest either they may work on your truck and not be making a couple pins on your fathers. i would start checking the pins on your fathers truck one buy one with a testlight\multimeter if you know they are good and the trailers are good it has to be a connection issue
     
  4. SnowMatt13

    SnowMatt13 PlowSite.com Addict
    Messages: 1,533

    7-pin plug and what I call harness is all the wires going into the back of the plug cannot be changed, it is wired to the plug and has a sealant on the back, the wires lead abour 16" to a plug.
    Yes the harness and plug both new. Sorry to call it a plug but I can't think of the right name......where you plug the male trailer end into.
    I use di-electric like its going out of style on my elec. stuff.

    I will check grounds this weekend when I get a chance.
     
  5. basher

    basher PlowSite Fanatic
    from 19707
    Messages: 8,992

    What color wire did you designate for each function?
     
  6. SnowMatt13

    SnowMatt13 PlowSite.com Addict
    Messages: 1,533

    On the trailers??
     
  7. basher

    basher PlowSite Fanatic
    from 19707
    Messages: 8,992

    When you re-wired the truck. That is when the issue started, correct? so you would have to assume that is where the problem is.