Trailer lights wiring help please

Discussion in 'Trucks and Trailers' started by crousehouse4, Mar 8, 2010.

  1. crousehouse4

    crousehouse4 LawnSite Member
    Messages: 7

    I'm trying to wire my trailer to the car so I bought one of the four wire connectors and this isn't working.

    Here's what I've got...
    from the trailer there are a total of four wires
    -brown and yellow go to the right side light of the trailer
    -brown and green go to the left side light of the trailer
    (there is no white wire comming from the trailer, I looked under it...just the two wires going to each light)

    from the car connector there are four wires...

    I tried connecting the two brown wires from the trailer to the one brown at the car, then green to green, and yellow to yellow... the nothing to the white. This didn't work.

    Any ideas?
  2. jsw2008

    jsw2008 LawnSite Senior Member
    Messages: 513

    I might not be understanding you correctly, but I think the white wire needs to be grounded to metal on the vehicle.
  3. FourTrees

    FourTrees LawnSite Senior Member
    from Zone 6
    Messages: 310


    You are good on other colors.

    There should be a white ground wire that runs to lights. Without it you have only a positive flow of power, and nothing to ground it to or in other words cause the "shock" to power the light.

    If there is no ground wire on trailer you are missing something, and may have to get some ground wire to run on trailer.
  4. crousehouse4

    crousehouse4 LawnSite Member
    Messages: 7

    That makes sense. The the thing is that when I bought the trailer the guy had it wired without a ground. SO, I assumed that I could wire it up the same way now. (The only reason I bought a new connector is that the other one came undone while I was driving and got messed up while dragging on the road.

    I need to figure out where to ground it now.
  5. Dave0013

    Dave0013 LawnSite Member
    Messages: 15

    Yellow - right blinker/stop light
    Green - left blinker/stop light
    Brown - parking lights (one wire on the car to both trailer lights)
    White - ground

    But the guy who sold you the trailer was "correct" in his wiring. You don't necessarily have to have a wire ground because most light kits ground directly to the trailer. If you look inside of the light housing, you'll see that there is a metal spade which contacts the trailer when you tighten the bolts. Therefore, the ground between the car and trailer is complete when you connect the trailer hitch to the ball. So... if you are doing this work and do not have the trailer hitched to the car (i.e. the car is merely backed up the the trailer), it won't work without ground wires from both the trailer and car. I never bother grounding any of our trailers and all of the lights have always worked.
  6. AI Inc

    AI Inc LawnSite Fanatic
    Messages: 26,797

    Just ground the white to any bolt ( you want to clean it up first , get all rust out) anywhere on the tounge. I usualy use something on or around the stand.
  7. crousehouse4

    crousehouse4 LawnSite Member
    Messages: 7

    Actually when I was trying it today I didn't have the trailer hitched to the car! I have to go try again...
  8. Dave0013

    Dave0013 LawnSite Member
    Messages: 15

    LOL. That's probably a more common mistake than you realize. Good luck!
  9. crousehouse4

    crousehouse4 LawnSite Member
    Messages: 7

    Still didn't work. I had the lights connected before but not the trailer hitch to the car. I just tried them again with the hitch to the car and there is no change.
  10. Richard Martin

    Richard Martin LawnSite Fanatic
    Messages: 14,699

    You should have a white ground on the trailer whether it's on the ball or not. Using the ball as a ground is what lazy people do. It can also cause the lights to flicker going down the road.

    Probably what the other guy was doing was just using the turn lights and nothing else. If you run 12v in on a brown wire and then run it out on a green or yellow wire the lights will still light because they share a common ground inside the bulb. It's definitely not the right way to do it and can result in some bizarre light behaviors.

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