Trailer tail lights stay on when nothing is powered

Discussion in 'Refrigerated Trucking Forum' started by Jennyspete, Feb 19, 2021.

  1. Jennyspete

    Jennyspete Bobtail Member

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    I'm not an electrical wizard by any means but this one has my mechanic stumped.

    I have no lights on the bottom rail of my trailer. Tail lights are dim and flicker. I do have brake lights. But here's the odd part. ABS light and tail lights stay on and continue to stay on even after I park shut off all light switches and turn the key off. The only way to shut them off it to unplug the pigtail. I do keep blowing the fuel for the trailer marker lights as well. Im pretty sure I have a short somewhere but I don't understand what could be feeding the tail lights and abs light when the key and switches are off. Any ideas are welcome.
     
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  3. AModelCat

    AModelCat Road Train Member

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    What truck? Issue could very well be there.
     
  4. Jennyspete

    Jennyspete Bobtail Member

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    I had it on a couple different trucks. 99 pete 379 and a 07 pete 379
     
  5. Roger McG

    Roger McG Light Load Member

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    Both trucks with same issue on the same trailer tells me the issue is in the trailer
     
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  6. Jennyspete

    Jennyspete Bobtail Member

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    Yeah, im sure its the trailer. Had a broken wire up near the fifth wheel plate. I fixed that but it did nothing.
     
  7. Joyce's Volvo

    Joyce's Volvo Light Load Member

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    You probably have a wire crossing over from the trailer 'hot line'. The blue wire in the 7 way is ' hot ' always, that is so if you need power in the van for lights . You pick up the hot line and run through a switch then , to 12 v lights so even with truck off you can see in the trailer. Pull the trailer 7 way out and look closely , ground is loose and center pin wire is more than likely crossing over to marker. It should be feeding back to truck cab lights or the marker there, may be very dim but see if their on also. Then unplug , if they go off , then it's the trailer for sure. Sorry, I mean the tail on tractor.
     
    Last edited: Feb 19, 2021
    jamespmack, DoubleO7 and Jennyspete Thank this.
  8. DoubleO7

    DoubleO7 Road Train Member

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    BINGO!!!! You are barking at the right tree.
     
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  9. DoubleO7

    DoubleO7 Road Train Member

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    I'm am betting you have a boogered up green cord where wires are contacting. It could also be in the box the cord plugs into.
     
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  10. Jennyspete

    Jennyspete Bobtail Member

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    Thanks ill check that. I had opened the trailer 7 way and I didn't see anything wrong in there however it was dark and cold out when I was looking so im sure I wasn't very thorough. On one of the trucks it also blew out my dash lights. Going to take it apart again tomorrow in the daylight. Ill post again with my progress, thanks for the info.
     
  11. abyliks

    abyliks Road Train Member

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    Ground somewhere or a wire, probably on the abs. I’ve already spent a few hours trying to fix old wiring on my trailer but I finally broke down and bought 2 new junction boxes to rewire Each side from the previous owners “my buddy great with wiring” layout, if you run in salt it kills everything.

    I pulled the constant abs wire out of the junction box and wrapped it in tape, but my old truck technically doesn’t need it, it still cycles with the brake lights, I’ll fix it on one of the nice spring days coming up instead of during a snow storm

    where do the bottom rail lights tie in? On the side, the rear, or a junction box?
     
    Last edited: Feb 25, 2021
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