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Plow Light Are Messed Up

Discussion in 'Fisher Engineering Discussion' started by DeereFarmer, Oct 23, 2008.

  1. DeereFarmer

    DeereFarmer PlowSite Veteran
    Messages: 3,296

    I hooked up my Minute Mount on my '02 GMC 2500HD today for the first time since I bight it this past summer. The plow works great, but the lights are messed up. When plugged is plugged in, the headlights on the plow do not work. The truck lights automatically go to bright and still have the regular driving lights on. The plow turn signals and amber marker lights work perfectly. When the plow is off the truck everything work on the truck as it should. I drove around with the plow attached for a while just to see what would happen and it blew the 15 AMP fuse for the passenger side headlights on the truck? I'm confused. Any insight?
     
  2. DeereFarmer

    DeereFarmer PlowSite Veteran
    Messages: 3,296

    Forgot to mention my truck also had DRL. Even when I disable the DRL by using the override button the problem still acts up. With the plow off, everything works as it should, once I replaced the fuse, but when the plow is hooked up the birghts are on on the truck no matter what when the headlights are turned on. When I disable the DRL the low beams and high beams are off. I can turn just the parking lights on, but when I turn on the headlights, it goes straight to the high beams.
     
  3. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    So this is the first time you had the plow on the truck and turned the lights on since purchasing it?

    Relay or Iso harness system?

    Time to start checking connections/bulb sockets and grill plugs for corrosion.
     
  4. DeereFarmer

    DeereFarmer PlowSite Veteran
    Messages: 3,296

    I drove it home with the plow on and I'm pretty sure everything was working correctly. If it works like it should without the plow on, would that still point at the ISO module? I'll start looking into things tomorrow when I get a chance.
     
  5. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Didn't mean it as a possible bad Iso mod DF. Just asking if your aware of which wiring system you have, makes a big difference for diagnosis help. :nod:
     
  6. DeereFarmer

    DeereFarmer PlowSite Veteran
    Messages: 3,296

    OHHHHH I got ya B&B. It does have the isolation module.:blush2:
     
  7. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    If it's blowing truck fuses its time to start checking connections/bulb sockets and grill plugs for corrosion as well as harness's for chaffing. :nod:
     
  8. DeereFarmer

    DeereFarmer PlowSite Veteran
    Messages: 3,296

    That will be tomorrow's project. Got too busy at work today. Oh well! Now when you say bulb sockets, do you mean on the truck, the plow, or both?
     
  9. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    All. :nod:

    But start with the plow side as thats likey where the problem is based.
     
  10. DeereFarmer

    DeereFarmer PlowSite Veteran
    Messages: 3,296

    Everything looks OK with the quick glance I gave it. I would think it is plow side seeing the truck works fine without the plow, but does anyone have a schematic for the wiring truck side? Like what color wires should go where? Both truck and plow are three plug setups, so they should be universal, right? If the bulbs in the plow light housing were bad, would it cause a problem like this?
     
  11. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    It's been known to happen.


    You can get any and all wiring diagrams from Fisher's website.
     
  12. DeereFarmer

    DeereFarmer PlowSite Veteran
    Messages: 3,296

    Now what should I be looking for B&B? I've fallowed the light wires all over the plow making sure they don't fround out or anything like that. All seems fine. I'll take apart the lights tomorrow and check in there.
     
  13. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Your looking for any cuts or damage on the wires, especially where they're near any edges and pass through's, corrosion in any of the plugs, and sloppy connections. This includes inside the light housings.
     
  14. DeereFarmer

    DeereFarmer PlowSite Veteran
    Messages: 3,296

    I looked over things very well today and found nothing. Cleaned all the connections and did a lot of investigating. Heres what I came up with:

    -No plow, truck lights work perfectly just as it should.

    -Plug in the two grille male/female connectors and plow headlights come on. Truck lights stay on also. High beams and low beams work correctly on both truck and plow. There are no turn signal or running lamps on the plow.

    -Plug in the final connection and plow headlights go out, plow turn signals and running lights come on, passenger side truck light blows a fuse, the drivers side high beam and low beam stay on constantly, and the high beam indicator is on on the dash.

    -Disconnect plow, replace fuse, and truck lights work fine.

    Hopefully this may narrow down my problem. Should I try to up the headlight fuses on the truck for a quick test and see what that does?
     
  15. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    DO NOT INCREASE THE FUSE SIZE!!!! :nono: Wont tell you a thing and may cause damage.

    Is this an old style relay setup, or an Isolation module harness?
     
  16. DeereFarmer

    DeereFarmer PlowSite Veteran
    Messages: 3,296

    It's an isolation module and I hear you loud and clear on the fuse. That's why I ask first!
     
  17. basher

    basher PlowSite Fanatic
    from 19707
    Messages: 8,992

    What's the condition of the grill plugs? Is the plow side rotted out?
     
  18. DeereFarmer

    DeereFarmer PlowSite Veteran
    Messages: 3,296

    The grille plugs are all in good shape. Clean with no broken or bent pins.
     
  19. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    Check the multi pin light harness where it runs from the Iso module out to the bumper. Could be rubbed through somewhere between there since there's plenty of sharp edges where those harness's are usually run.

    Have you tried to connect it with the HIGH BEAMS on instead of the lows? Would help you narrow the possibilities down some.
     
  20. DeereFarmer

    DeereFarmer PlowSite Veteran
    Messages: 3,296

    I checked the wires all the way through, no cuts no problems that I can find. I'll try to hook it up with the highs on and see. I'm bringing it to my shop tomorrow. The truck needs a few things done, so I'll just have the plow fixed there if I can't find anything. Thanks for the help like always B&B.