Trailer Light Hook-up?

Discussion in 'Lawn Mowing' started by LoneStarLawn, May 18, 2001.

  1. LoneStarLawn

    LoneStarLawn LawnSite Bronze Member
    Messages: 1,415

    Got another trailer not to long ago and notice that the lights on it were not working. After checking the wiring near the connection ...I noticed that the ground wire was not attached to anything. It wasn't noticeable before because it was encase within a sleeve to protect the wiring. The lights work when I touch the wire to the trailer, but not everywhere. I don't remember how the other trailer was hooked up so I'm wondering where in fact does the ground wire attach to ground the circuit?
  2. John DiMartino

    John DiMartino LawnSite Silver Member
    Messages: 2,555

    You didnt mention which style connector you have,but either way it should be the white wire on the trailer side of the connector.That is the ground wire for the trailer,I run it to the tongue of the trailer with a nut bolt,and some synthetic grease to keep corrosion away a little longer.In the back of the trailer,you can attach the tailights ground wire to the mounting bolt of the tailight,just clean off any paint,coat with grease so you get a good connection.The trailer frame acts as a ground on 99% of the trailers I've seen.If your truck side ground is bad,as you drivr,and the trailer ball scrapers clean the inside of the tongue,it will make a ground,and the lights will start working.This ground is not reliable,especially when the trailer is empty,the lights will flicker over bumps.I go over my lights at least once a season,they always need to have connections cleaned,and sockets greased so they stay tip top.If only some of your lights are working,you need to check the sockets for wear,and use a test light to find out if the socket has power-or wire/connector broke.
  3. TLS

    TLS LawnSite Fanatic
    Messages: 7,943

    The ground wire should attach to the frame of the trailer or any clean metal that is welded to the frame.

    Sorry, John beat me to it. Anyway, factory trailer wiring is usually junk. I 3 yrs ago completely rewired the entire trailer with quality Betts lights and epoxy wirenuts. Haven't had a bad light since.
  4. LoneStarLawn

    LoneStarLawn LawnSite Bronze Member
    Messages: 1,415

    It is the white wire...The lights are hooked up but for some reason the manufacturer or whoever did the lights forgot to attach the ground wire...Im not sure that the lights are even grounded to the frame since there is just two wire going to each tail light of the trailer (running lights and turn/stop light)
  5. TOSLC

    TOSLC LawnSite Member
    Messages: 175

    The last two posts are right the white wire is your ground, and usually the ball hitch acts as your ground to the truck. Many trailer manufactures use the ball to ground the trailer to the truck. I don't know about you but the ball hitch to my trailer is very rusty. Therfore hook the trailer wire to the truck wire. Also many lights use the mounting screws to ground the light to the trailer, this can also present a problem when the hole for the screw gets rusty. You have two options, ONE - use a crimpable connector on a piece of wire to hook the mounting screw directly to the white wire on the trailer, TWO - go to a truck stop or find a manufacture of semi-truck lights, most trucks now have fiberglass side skirts that don't allow for the lights to be grounded via the mounting screws, therefore they have a ground wire already attached to them making it easy to use. Another plus is many of the lights have a sealed casing (much like the sealed beam headlights) around the bulb making them water proof, easy to install, and easy to change. The only downside is they cost a little more.
  6. racerdave

    racerdave LawnSite Senior Member
    Messages: 260

    I've always had the best luck running the trailer ground thru the plug to the truck ground. I just don't think we should rely on the hitch ball for the ground. On most electrical circuits, a loose connection is a recipe for a failure.(which in fact a trailer ball would be). You can ground your lights to the trailer frame, but I still recommend you run the ground thru the trailer plug and to the truck ground. If you have the factory plug on the truck, I'm sure you will have the ground already present.
  7. Eric ELM

    Eric ELM Husband, Father, Friend, Angel
    Messages: 4,830

    Most trailer MFG use the trailer frame as the ground for the lights, but run a ground wire to the brakes. If they would just run an extra wire to the lights too, you wouldn't need to run a ground to the trailer frame.

    I agree with racerdave, that the ball should not be used as the ground source. This will make the lights blink on and off if the trailer is empty. Use the ground on the plug so it goes directly to the truck, it is the best way.
  8. LoneStarLawn

    LoneStarLawn LawnSite Bronze Member
    Messages: 1,415

    I guess I didn't make my self clear...(I apoligize for that) Some gave to much detail on the wiring concept ( again that was my fault, I must have come off as an idiot ;) ) All I really wanted was an actually location on the trailer to connect the wire for a good connection...but anyways I actually found a good connection on the trailer and have fixed it already....Thanks for trying though

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