Possible grounding issue. Need advice.

Discussion in 'Trucks [ Eighteen Wheelers ]' started by wpd304, Aug 2, 2011.

  1. wpd304

    wpd304 Bobtail Member

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    Feb 5, 2011
    Allendale, MI
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    I'm having some issues with keeping liftgates charged on a few different trailers, which leads me to believe the problem is on the truck side and not the trailers. I've changed the single pole socket, wiring, and cable. I hooked up a load tester to the single pole and grounded ir to the catwalk and I get a good reading. I then grounded it to the trailer and it reads weak.
    I've tried moving the 5th wheel but that didnt seem to help. What's the best way/place to attach a ground strap to the 5th wheel? Any other suggestions?
     
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  3. Heavyd

    Heavyd Road Train Member

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    Just drill a hole in the side of the 5th wheel and another in the frame near by and use one of those flex mesh braided ground straps to ground the plate to the frame.
     
  4. Sparkz

    Sparkz Light Load Member

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    Jul 10, 2011
    New Zealand
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    Suggest adding another socket for a ground wire rather than relying on metal to metal contact across the fifth wheel.
     
  5. Rubber_Duck

    Rubber_Duck Light Load Member

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    Great Bend, KS
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    Isn't there a ground wire in the light cord? The individual lights are grounded to the trailer, but the whole trailer ought to be grounded through the white wire... the top center electrode in the plug/trailer light cord receptacle.

    I would tend to think that if your trailer lights are working ok, you should also have a good ground from the entire trailer to your tractor via the light cord, even if you're not getting any conductivity through the 5th wheel.

    Here is a photo I took of a sticker on the front of a Great Dane trailer.

    [​IMG]
     
  6. CondoCruiser

    CondoCruiser The Legend

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    That's what I was going to say rubber duck. The chassis ground is carried through to the trailer through the pigtail. I would look under the front of the trailer and make sure the chassis ground is in good shape.

    Being an intermittant problem where some lift gates work and some don't, tells me it's on the trailer side.

    If they relied on the 5th wheel to carry the ground, they would be using dieletic grease on it.
     
  7. DL550CAT

    DL550CAT Road Train Member

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  8. Rubber_Duck

    Rubber_Duck Light Load Member

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    Great Bend, KS
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    If the lift-gate was being powered directly from the truck's batteries, you would need heavy gauge wire. If it's only drawing power off the truck to basically trickle-charge a deep cycle battery for the lift-gate, a heavy wire gauge isn't needed. The stranded wire in your average typical light cord would do just fine.

    And to prove I know what I'm talking about, I'll use this little brainy-looking character with the glasses >>>>> :biggrin_2558:
     
  9. DL550CAT

    DL550CAT Road Train Member

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    The op said he changed the single pole socket meaning its 1 of those pig tails that looks like it has a bunch of wire in it but only has 1 very large wire in it.
    One of the reasons the pigtail has a ground wire in is to ground all the lights back to the truck and not use the trailer body as a ground source. This cuts down on corrosion and the possiblity of creating a ground loop.

    The brainy looking character does not fool me.
     
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