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Plow Lights go out when I turn Brights on

Discussion in 'Sno-Way Discussion' started by mklawnman, Nov 25, 2006.

  1. I have a 2003 Model plow for a 2000 F150, it is a 7'6" plow i think the MT series, with the older style electrical hookups with a relay. When I go to put the lights on high beam the lights go out. I've taken the relay out and unplugged all the hookups and cleaned them and put dielectric greese on it and put all the wires back matching the numbers on the relay to the wires.
    Is my relay bad? Or is it a bad wire that has corroded? I did notice that on one of the plugs for the lights the stud had come off and is stuck in the recieving end of the plug, not sure if thats for the ground or wha. The lights do work in low beams and the turn lights and park lights all work, just not the high beams.
  2. LLM Ann Arbor

    LLM Ann Arbor Senior Member
    Messages: 876

    Id look closely at the wiring again. |It sounds like corrosion.

    Corrosion is the death of these things and the root cause for a lot of if not most of the issues with plow lights and weird unexplained changes in performance.

    Good luck.
  3. basher

    basher PlowSite Fanatic
    from 19707
    Messages: 8,993

    Take a test light to it. If the broken pin has juice when you turn the high beams on, then that's your problem. If not test the relay to see if it's switching over from truck to plow.
  4. DBL

    DBL PlowSite.com Addict
    Messages: 1,310

    check the bulb it may not be a high low bulb so when you hit the high beams it throws it back to the truck lights
  5. toby4492

    toby4492 2000 Club Member
    Messages: 2,513

    Basher is giving you good advice. A test light should let you know pretty quick whether it is the harness or the relay.