Light/electric problem

Discussion in 'Freightliner Forum' started by xsetra, Feb 7, 2021.

  1. xsetra

    xsetra Road Train Member

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    1999 Fld120
    I was standing beside my truck, it was turned off. The trailer lights just turned on.
    I had been parked a couple hours. I haven't noticed the before.

    I checked my wiring connections from trailer to main panel. My brown and black circuits are live. Also my dash lights stay on.
    No other truck lights come on unless I turn the switch on for them. All turn signals and brake lights work normal.

    I pulled the relay and the trailer circuits stay on. 16127494110547091290912747764932.jpg

    The relay buzzes when I put it in, I tried with a different relay, same result. Trailer and dash lights stay on with this relay removed.

    I'll try any suggestions in the morning.
    Thanks for any help.
     
    Last edited: Feb 7, 2021
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  3. Rideandrepair

    Rideandrepair Road Train Member

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    My guess is you’re problems right there. Looks like someone has already replaced the 7 wire to pigtail. I only see 6. Almost looks like the brown is jammed behind the white. It’s hard to tell. I’d try disconnecting each one, starting with the brown wire. I can’t really tell which wire is what color. But one of those is probably shorting out. Maybe they just crimped new ends on, could be bad crimp, or a broken wire in the run somewhere. New 7 wire from fuse panel to pigtail receptacle should fix it. I’d still disconnect them first. See what happens, wires broken somewhere, may be 2 wires touching in the run. New 7 wire can be bought by the foot at any trailer supply.
     
    Last edited: Feb 7, 2021
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  4. xsetra

    xsetra Road Train Member

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    The trailer wire was replaced couple years ago. The old wire wasn't pulled out. It's pushed to the bottom of box.

    I did disconnect the trailer feed. The trailer side and rear marker lights (brown and black) lugs are live even with the light switch turned off.
     
  5. mslashbar

    mslashbar Medium Load Member

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    Wouldn't hurt to check switch in the dash to make sure its not shorting out
     
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  6. AModelCat

    AModelCat Road Train Member

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    Sounds like you've got a power wire shorted to your trailer lights.

    I would start by pulling the fuses for the affected lights and see how the lights respond. If they stay on, you've got a short to 12 volt somewhere.

    Could also pull fuses out one at a time and see which circuit is supplying the power. At least that dials you in to where to look closer at.
     
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  7. xsetra

    xsetra Road Train Member

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    Light switch has 6 poles. 2 bottom control headlights and marker.
    2 center my guess power in.
    2 upper just marker lights.

    I had constant power to both center pins.of harness to switch.

    Yesterday I ran thru a lot of rain.
    This morning I put everything back the way it was.
    All the lights seem to work properly and that relay stopped buzzing. Except if I turn just marker lights on. Trailer lights stay on, when I turn switch off.
    If I turn switch up for marker lights and headlights then off, all the lights go off.

    I know there's power feeding the system somewhere. I'm in Miami going to Fargo. I hope everything dries out before I get there.
    Thanks for the replies.
     
    Last edited: Feb 8, 2021
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