trailer wiring ?

Discussion in 'Trucks and Trailers' started by fairwayCuts, Aug 30, 2005.

  1. fairwayCuts

    fairwayCuts LawnSite Member
    Messages: 161

    I've recently had to re-wire my trailer. So far everything seems to bee working except one thing. Parking lights- ok / rt turn signal - ok / lt turn signal - ok / brake lights don't work. When I apply the brake on my truck the truck brake lights work, but my trailer light go out. When the brake is un-applied the parking lights come back on.

    a few notes.

    The light bulbs are double filament lights.
    The light bulbs are installed correctly
    The light bulbs are not blow.

    Any suggestions??
  2. hosejockey2002

    hosejockey2002 LawnSite Bronze Member
    Messages: 1,195

    I'd bet you have a bad ground. Make sure the plug on the truck is grounded to the frame of the truck and the plug on the trailer is likewise grounded to the trailer frame. Also, make sure that the ground connection through the plug is good. Last, make sure all the trailer bulbs are grounded to the trailer frame. Don't depend on the receiver and coupler to provide the ground connection.
  3. grass_cuttin_fool

    grass_cuttin_fool LawnSite Gold Member
    Messages: 3,526

    a bad ground is the problem, its the white wire in the harnes
  4. start2finish

    start2finish LawnSite Senior Member
    Messages: 497

    if you have both turn signals, then double check your wiring at the truck to be sure the truck is wired properly. Most trailers do not have a brake wire (unless of course it is to the electric brakes) but just applied both turn signals solid. The lights on your truck work the same way.(unless you have amber turn signals) then your probably need a kit to sort this out on the truck.
  5. muddstopper

    muddstopper LawnSite Silver Member
    Messages: 2,341

    Ground is a likey problem but You might also have a tailight brake light wired wrong. If your taillights are both dim when on, this is probably not the problem, but if one taillight is bright and one dim then the wires are crossed on the bright one. Both tail lights run off of one wire, usually the brown wire, when you apply the brakes you are shorting out the brakelite and taillight which can cause the lights to go out, such as your problem, or all of them to come on. Since you have both turn signals you probably havent crossed the wires but it doesnt hurt to check. Most taillights donot have a ground wire ran to the light but depend on the lite housing bolts to ground them to the frame. Since some light houseings are plastic, and frames rust, a good ground is hard to get using this method. I added a short wire from the bolts to the frame to insure a good ground. A two dollar roll of wire will reach from the front to the back of most trailers and it is a good ideal to run a ground from the lights all the way to the ground at the plug to help prevent losing ground. Use white for a ground wire. I used 14 ga wire on mine but you can get by with smaller. I would also double check the wires at the plug. I dont know which type of plug you are using but those flat plugs are hard to mess up, just line up the colors. Its the round 5-6 & 7 wire plugs that will mess with your mind. Not that they are all that hard to wire, its just that you are always looking at the back side of the plug and sometimes you can reverse the wires even tho you know which direction they are supposed to go.
  6. fairwayCuts

    fairwayCuts LawnSite Member
    Messages: 161

    :dizzy: thanks for the replies! I did wire a whole new ground for my trailer, which is grounded on the toung of the trailer. I'm still having the troubles though?? :angry: . Question, and this may sound dumb, but I do not want turn signal and tail light wire spliced together, correct. I do not have it that way but it's about the only other thing I can think of. I've tried the wiring set up on 2 differnt truck and the same thing happens, so I do'nt believe it's a truck ground problem.
  7. fairwayCuts

    fairwayCuts LawnSite Member
    Messages: 161

    well, looks like I was having a bone head day!! All it was is because I didn't screw the tail light fixtures back on. I had them just sitting on the trailer so I could see the lights from my diver seat!!! AHHHHHHH :angry: :angry: . But in the end, with your guys help, I screwed them back in and that grounded the rear lights like you said and BINGO!! :angel:

    Thanks again guys!
  8. start2finish

    start2finish LawnSite Senior Member
    Messages: 497

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