2015 Peterbilt 389 trailer turn signal issue

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by MT927, Jun 23, 2023.

  1. MT927

    MT927 Bobtail Member

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    3
    Jun 23, 2023
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    Trailer passenger side turn signals keep going out. Haven’t dug too deep in to it yet but tested all the 7 way connections, ended up replacing the outlet off the truck and it lasted a a day.

    one strange thing that did happen was the one time I tested the outlet it blew the 20 amp fuse under the hood labeled Power G5, now the lights go out without blowing that fuse, today I replaced the perfectly good fuse for the hell of it and they started working again and I’m baffled.

    Any ideas or input would be appreciated.
     
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  3. Concorde

    Concorde Road Train Member

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    West Melbourne Florida
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    I chased a trailer light issue for two days just recently.. I even bought a new pigtail and the problem was worse..no lights and would blow a fuse every time I touched the brake pedal.

    The brand spanking new pigtail had none of the wires connected to the plug end and was shorting out. Slid the end covers back on the old pigtail and there it was..one wire detached..fixing all my problems!

    Slide both covers back on your pigtail and check that all wires are secure. It’s just a easy simple check that won’t waste much time.
     
    D.Tibbitt and BoxCarKidd Thank this.
  4. MT927

    MT927 Bobtail Member

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    Jun 23, 2023
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    I’ve checked and double checked all wiring on the 7 way outlets on truck and trailer and the 7 way cord, no loose, broken or deteriorated wires.
     
    Concorde and D.Tibbitt Thank this.
  5. D.Tibbitt

    D.Tibbitt Road Train Member

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    Apr 26, 2013
    Gettin' down westbound
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    is it only turn signals? electrical problems you really gotta take the time to diagnose with a test light.. if its blowing a fuse i would say the cable has rubbed thru and grounding out on the frame somewhere.. sometimes like looking for a needle in a haystack
     
  6. MT927

    MT927 Bobtail Member

    3
    3
    Jun 23, 2023
    0
    It is just the turn signals on the passenger side, waiting til I get home to my shop to diagnose it further. Really just looking for input on the fuse thing that happened where the lights weren’t working and the fuse wasn’t popped and I put a new fuse in and they started working then out the old fuse in and still worked. Maybe fuse panel wiring or prong issue?
     
    D.Tibbitt Thanks this.
  7. D.Tibbitt

    D.Tibbitt Road Train Member

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    Gettin' down westbound
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    It could definately be some corrosion in there. If it is fuse panel under the hood. Maybe some water got in there..
     
    LoneRanger Thanks this.
  8. jimkas

    jimkas Bobtail Member

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    Jun 4, 2023
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    try a bigger fuse from 20 to 30 etc
     
  9. FLHT

    FLHT Road Train Member

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    Aug 2, 2014
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    Ceramic piece on back of 7 way plug on back of tractor may be cracked and shorting out.
    Your signal stat may be worn out and shorting out . Open it up clean it up and see.
     
    LoneRanger Thanks this.
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