Re-wiring trailer

Discussion in 'Trucks and Trailers' started by Phishook, Aug 10, 2003.

  1. Phishook

    Phishook LawnSite Bronze Member
    Messages: 1,143

    Simple right? Ha! 6 hrs later I'm looking for some help.

    Putting all new lights and wire on the trailer. Two tail lights with turn signal, and two marker lights.

    Lights from truck work fine.

    Take me through this step by step. Nothing is working.

    Ground to trailer frame?

    Tail lights from truck to left tail then to right tail?

    Right turn to right turn?

    Left to left turn?

    I have the marker lights spliced into the tail light wire?

    These light ground to the bolts, so there isn't a ground wire on the lights. I sanded the paint off where the bolt and nuts ground.


  2. MP350

    MP350 LawnSite Member
    Messages: 185

    Try testing the plug from the truck, if that all works try testing the wire where you connect to the lights to make sure it works. a test light comes in handy for this
  3. Phishook

    Phishook LawnSite Bronze Member
    Messages: 1,143

    Have several testers. Truck is fine.

    Blew two tail light fuses on truck. Replaced.

    Wires get hot, fast.
  4. MP350

    MP350 LawnSite Member
    Messages: 185

    Wire could be to thin,could be to many lights for system, or could be a short, just to many things it could be I know this ain't much help but with out looking at it in person I am just quessing
  5. mh1314

    mh1314 LawnSite Member
    from Texas
    Messages: 133

    Quite obviously have power going to ground. Wrong wire hooked to ground or skined wire touching ground. If you're using a four-way plug check against these codes and make sure the color continues into the trailer plug and wires.

    The common flat 4 wire connector used on boat, snowmobile, and light utility trailers most commonly uses the following code.

    Flat 4 wiring code
    white ground
    yellow left turn/brake light
    green right turn/brake light
    brown tail

    Factory installed wiring harnesses frequently match the flat 4 colors.

    Notes about GM OEM wiring harness. Most GM vehicles except '99 & 2000 Silverados match the following.

    GM trailer wiring code
    white ground
    yellow left/brake
    green right/brake
    brown tail
    light green backup
    blue trailer brakes
    red * 12 volt +
    * Pickups only: since approximately 1996 the 12 volt + wire is orange. The orange and blue wires are in a separate bundle taped to the wire harness that runs down the frame on the drivers side. A white wire may also be found in that bundle, it is a brake light wire which is not normally used for trailer wiring.
  6. turfguy

    turfguy LawnSite Member
    Messages: 141

    without being right there I would recomend that you first hookup your trailer to your truck. then connect the ground wire to the trailer first and then connect each wire one at a time and test out its proper function. if you blow a fuse after conecting a spacific wire start tracing that one out. I have a E/E degree and trailer wiring is still a pain in the ----- to me. good luck feel free to email me with any ?? mark
  7. Phishook

    Phishook LawnSite Bronze Member
    Messages: 1,143

    Power going to the ground is what is probably shorting everything out right?

    Well, going back to the shop. Be back in a few Hrs.

  8. o-so-n-so

    o-so-n-so LawnSite Bronze Member
    from Alabama
    Messages: 1,218

    There a basically only 3 circuits for the trailer lights. 1. Marker lights. They come on when the lights are on. 2. Right turn/Brake. 3 Left turn/ Brake.

    I would go buy a four pin trailer wiring kit. Available in different lengths.

    Green=Right turn/Brake
    Yellow=Left turn/Brake

    Good Luck.......
  9. paponte

    paponte LawnSite Silver Member
    Messages: 2,366

    What kind of truck are you working with? I know that with mu UD I was racking my brains out, before I found out I needed a converter box. :cool:
  10. mh1314

    mh1314 LawnSite Member
    from Texas
    Messages: 133

    If you have a four way flat plug on your vehicle, take your test light and try out the three wires. Turn your healdights on and put the test light in the brown wire and ground to the white one. If you get a solid light this is fine. Next turn on your turn signal and test the coresponding wire and also go to the white. You sould get a blinking light on your tester. do the other turn signal the same way. If for any reason none of them light up, crawl under the vehicle and check that the white goes to ground. Alot of places still try and use the hitch as gound.

    If it checks out then make sure your brown wire runs to the marker lights and to each rear light and attaches to brown. Turn on your healights and then should light up the side markers and taillights. If you lose a fuse you have an exposed wire to gound. No light will mean you have a bad connection in that wire somewhere. follow out the two remaining wires the same way.

    If for some reason your tailights are brighter than the stop or turn signals, then reverse the wires on the back lights.

    Hope this helps

Share This Page