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Trailer lights problem

Discussion in 'Trucks and Trailers' started by sandman23, Apr 21, 2009.

  1. sandman23

    sandman23 LawnSite Member
    from GA
    Messages: 212

    I purchased new trailer lights and wired them. They came with two marker lights as well. I believe the wire colors are universal so I will describe my install. Brown and Yellow to driver side, Brown for TAIL and Yellow for STOP/TURN LEFT. Green an Brown to passenger side, Brown for TAIL and Green for STOP/TURN RIGHT. Marker lights hooked to Browns.

    Passenger side works fine. Driver side has issues. When I turn on left signal, it blinks but not in unison with truck signal. No big deal except passenger side blinks in unison.

    Both brake lights come on without headlights on. When headlights are on and I step on the brake driver side lights go out. Also, when headlights are on, driver side is dimmer than passenger side.

    Any ideas? Fuse, ground, crossed wires?
  2. seabee1

    seabee1 LawnSite Member
    Messages: 239

    yellow left turn,green right turn,brown running lights white ground ,blue elec brakes black 12 vt power sound's like a ground problem .check the ground between the trailer and truck in the plug ,also check the ground at the tail lights .the usually ground through a mounting bolt ,clean to bare metal ,coat it with dielectric grease at the ground point's .the light's and wiring is were they cheap out . the light's are crossing over from a bad ground . :usflag:
  3. Jason Rose

    Jason Rose LawnSite Fanatic
    Messages: 5,858

    Check the plug on the back of the tow vehicle and make sure that it's wired correctly. You can check online for the standard wiring configuration depending on what type of plug you have. Colors don't really matter unless you are certian that both the truck and trailer are wired properly.

    Once you determine that your vehicle and trailer plug are correct, then you can move onto other items. I've had a bad light fixture before, brand new, and one hair of a wire was touching another connector in one of the tail lights. Caused me a bunch of headaches and cussing before I found it. Even a defective bulb can cross power over from one circut to another. Not sure what kind of lights you got though... Usually LED's are made a little better. I haven't had any troubles with the LED's other than grounding. They need a really good ground to work properly. (as do all 12v lights, but LED's are very low current and are even more sensitive to poor grounding.)
  4. IdealLawnCare

    IdealLawnCare LawnSite Member
    Messages: 159

    Check to make sure the bulbs in the trailer lights are seated properlytoo, but it sounds a lot light a ground issue. Tail lights bolted where there is rust or ground wire near coupler isnt making good contact.
  5. Dano50

    Dano50 LawnSite Bronze Member
    Messages: 1,781

    Use Fluid Film to protect from corrosion. It works excellent for electrical connections. Just make sure your connections are tight. Fluid Film is non-conductive.
  6. terrypiper

    terrypiper LawnSite Member
    Messages: 115

    are you using a flat four conector? no brakes on trailer? if thats the case then brown on both sides is for stop and tail yellow and green are to the correct sides and are for turn only. sounds like a ground problem or a bulb problem as mentioned before.
  7. LewisLawn

    LewisLawn LawnSite Senior Member
    Messages: 517

    have dealt with that problem b4 myself and after many headaches it is usually poor ground...if evrything lights up you know you are getting the juice to the bulb but with problems of sequencing and brightness it is usually the ground..never hurts to add and extra ground beyond the four plug white wire(i believe it is white without looking)...but i agree about the fluid film..i recently hooked my trailer up had break lights, fourways and turn signals but no tail lights cleaned out the receptical and sprayed a little cleaner in them and now everything works fine...
  8. markahurley

    markahurley LawnSite Senior Member
    Messages: 252

    i went through the same thing with my taillights too--i found my problem was the wires got pinched between the light housing and the trailer--pinched enough to go through the insulation and make contact with the bare wire--creating a weird circuit that kept doing all kinds of weird things. so yeah--check your grounds, and also check your wires that you haven't done the same thing.
  9. Horsepower Lawns

    Horsepower Lawns LawnSite Member
    Messages: 213

    Thats wrong.:confused:

    Brown = Tail
    Yellow = Left Turn & Brake light
    Green = Right Turn & Brake light

    Like others said, check your grounds.
  10. sandman23

    sandman23 LawnSite Member
    from GA
    Messages: 212

    Thanks for all the replies. It was a ground problem. Where the light mounts to the trailer, apparently the paint was too thick. I sanded the area and they work fine. Thanks again.

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