Service Trailer Brake System activates only when plowing

Discussion in 'Chevy Trucks' started by Motorman 007, Dec 4, 2019.

  1. 2015 GMC 2500 HD Fisher XV plow. Service trailer brake system light and alarm activate from time to time plowing. One would assume this is a wet wiring or plug issue but it never does it in the off season even when driving in heavy rain and puddles. Any ideas?
     
  2. cwren2472

    cwren2472 PlowSite Fanatic
    Messages: 8,577

    Snow build up getting kicked into the back of the plug and sticking there
     
  3. OP
    OP
    Motorman 007

    Motorman 007 Senior Member
    Messages: 929

    Have you seen this before??
     
  4. cwren2472

    cwren2472 PlowSite Fanatic
    Messages: 8,577

    Yes. It happens on aftermarket controllers also and often shows as flickering displays. I wouldn't say it's common but it happens. The back of the factory plugs are pretty poorly sealed.
     
  5. Mark Oomkes

    Mark Oomkes PlowSite Fanatic
    Messages: 33,045

    Toro supplies them to GM?
     
    mnlawns and m_ice like this.
  6. cwren2472

    cwren2472 PlowSite Fanatic
    Messages: 8,577

    Actually it's one of the few universal pieces in the auto industry. Its called USCAR and despite the US in there, it's the same socket used by Ford, Dodge, GM, Nissan, Toyota, VW, oh and everyone else too. K, lesson over.
     
    Motorman 007 likes this.
  7. m_ice

    m_ice 2000 Club Member
    Messages: 2,170

    There is also a trailer brake controller relay that could be the culprit
     
    Motorman 007 likes this.
  8. OP
    OP
    Motorman 007

    Motorman 007 Senior Member
    Messages: 929

    I pulled everything apart this morning. Absolutely no indication of moisture penetration from the back side of the plug. Cleaned it up anyway and put some dielectric grease on the plug terminals inside the bumper socket. We’ll see but I’m not encouraged.
     
  9. OP
    OP
    Motorman 007

    Motorman 007 Senior Member
    Messages: 929

    So this issue keeps happening intermittently and now it does it without the plow on the truck. Scanned the truck for codes and nothing comes up. Ordered the gain switch for the dash since that seems to be the most popular repair after researching the various forums that are online. If that doesn’t work, I’ll have to get the module that is up above the spare tire.
     
  10. 16hdsport

    16hdsport Senior Member
    Messages: 139

    Is your plow pulling power from the battery, or the trucks fuse box?

    I asked because I had the same message flash on my Dash when my truck lost all communication. Turns out the dealer had wired the plow to the fuse box which was intermittently causing issues with the trucks computer system.
     
  11. OP
    OP
    Motorman 007

    Motorman 007 Senior Member
    Messages: 929

    It is wired to the fuse box under the hood. It has to be keyed power.
     
  12. 16hdsport

    16hdsport Senior Member
    Messages: 139

    I would have them check it. While my plow needs the ignition to be keyed for it to run, the direct power comes off the battery stud for the positive terminal
     
  13. OP
    OP
    Motorman 007

    Motorman 007 Senior Member
    Messages: 929

    Sorry. Misunderstood you. My controller is keyed power. Otherwise the plow is installed with the battery cables direct to the battery.