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Help Me Please. Left headlight fuse keeps blowing.

Discussion in 'Truck & Equipment Repair' started by theIceNSnowman, Feb 4, 2015.

  1. theIceNSnowman

    theIceNSnowman Member
    Messages: 65

    Hello Everybody,

    Been a while, but I'm hoping you guys can help me before I have to take her in to the shop.
    Vehicle: 2010 F350xlt, gas. 45k mi
    Plow: 2012 Fisher xtreme V stainless 8.5'

    I have literally had zero issue with this setup since I pick it up in January 2012. All of a sudden, about a week ago, I noticed that my left headlight was out on my plow.

    What I know:

    Its not the bulb. Hi beam works fine, and if you change the fuse (left headlight, low-beam), low beam comes on for a second and blows.

    I pulled the headlight out and there are no signs of damaged wires or corrosion. I disconnected the plow wiring and tried the headlight and it works, without issue.

    Therefore, It's not the truck. phew.

    Its not the plow because.... While I had the headlight out, i plugged back in the wiring harness, and tried the lights, without the plow plugged in, and off the truck. Blew the fuse. So its in the harness for the plow I guess?

    So am I to believe it is that little computer box that probably will cost an arm and a leg? Am I missing anything?

    Thanks in advance.
  2. dieselss

    dieselss PlowSite Fanatic
    Messages: 11,395

    Your headlights for your plow come on when you hook up the plow.
    So, it's wiring from the trks headlight to the Iso module, back out from the module to the plow via lots of wires.

    I'm saying start cking for pinched wires somewhere, plowside.
  3. theIceNSnowman

    theIceNSnowman Member
    Messages: 65

    Note : without the plow on the truck, with the fisher wiring harness plugged back into the headlight, it blows a brand new fuse. every time.
    If I unplug the wiring harness from the truck, it does not blow a fuse when I turn on the headlights.
  4. k1768

    k1768 Senior Member
    from NJ
    Messages: 556

    Do you have a multimeter?
    With power OFF, pull the fuse, check for a short between load side of the fuse and ground. If there is a short, start following the wire to see where it is pinched. If you know what pin on the plow side controls the lights, you can do the same there. Check for continuity between pin for headlight and plow frame and other sources of ground.
  5. dieselss

    dieselss PlowSite Fanatic
    Messages: 11,395

    Then it's the plow harness, like I said start tracing wiring