Dumb Trailer ABS issue

Discussion in 'Volvo Forum' started by simonsocm, Apr 14, 2021.

  1. simonsocm

    simonsocm Light Load Member

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    Aug 17, 2019
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    15 Volvo vnl 670

    2 trailers were doing the blinky ABS light crap while braking. 40 fuse kept blowing.

    I bypassed the blue aux wire directly from the back of the fuse box under the hood to a jumper harness that connected the rest of the stock 7 pin wiring except for the blue aux wire (with the new one from the fuse box) into a new receptacle. Worked for ten mins and blew a fuse. I then cut that new wire and rigged up a fuse holder directly to the battery with a 50 amp capable toggle switch. That worked for tens mins and the fuse blew.

    I've replaced the pigtail right when it started happening.

    Whenever it fails I'm getting the trailer abs light on the dash still when I hit the brakes.



    Two trailers
    Two different power sources
    New pigtail
    Part of old pigtail was cannibalized to make AUX wire adapter harness BUT the fuse still failed when that wasn't connected.
    The push in receptacle on the back of the cab tested good btw. But it's intermittent so idk.


    What am I missing?!
     
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  3. Snailexpress

    Snailexpress Road Train Member

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    Two trailers could be serviced (assembled) by the same dumb person. Have seen it.
    Disconnect trailer ABS module and check what happens.
     
  4. AModelCat

    AModelCat Road Train Member

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    Sounds like a wire issue somewhere between the receptacle behind the cab and wherever you're splicing into it.
     
  5. simonsocm

    simonsocm Light Load Member

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    Aug 17, 2019
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  6. simonsocm

    simonsocm Light Load Member

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    I'll try that. Thanks!
    I also think I'm going to test all the lights with the pigtail disconnected to check for shorts in the factory harness.
     
    Snailexpress Thanks this.
  7. simonsocm

    simonsocm Light Load Member

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    Aug 17, 2019
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    Looks like it's probably in the trailer harness to the abs module. I disconnected it and drove 7-8 mins to my drop and it blew the fuse for the abs that's hooked straight to battery and bypassing the factory truck wiring.

    Figures I'd get two trucks that have ABS issues in a row. I'm still going to bobtail around a little later to see if for some dumb reason the pigtail I just bought is bad but I doubt it is.
     
  8. Cattleman84

    Cattleman84 Road Train Member

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    If the abs light on the trailer blinks the same each time it could be a blink code. If it is possible to count the blinks you can look that up and figure out what the code is.
     
  9. simonsocm

    simonsocm Light Load Member

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    Aug 17, 2019
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    It ended up being a chaffed wire behind the pigtail receptacle of the trailer btw. Now I have an adapter to test factory wiring I guess lol
     
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