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Ground issues?

Discussion in 'Fisher Engineering Discussion' started by DieselSlug, Dec 8, 2010.

  1. DieselSlug

    DieselSlug PlowSite.com Addict
    Messages: 1,050

    Just this season my plow lights have not been functioning correctly on my '94 Fisher MM1. With the plow on the truck and the plow is raised the plow lights work correctly (ie: both beams and turns). But when i lower the plow to the ground the lights convert over to my truck. I have to be having a grounding issue between the plow itself and the push plates right? IIRC, my plow lights are grounded to the head unit. When i put a set of used MM1 headlights on the plow the harness has a faulty connector in it. So when i plugged it into the truck the lights didnt work. But when i grounded them to the head unit they did. I needed them fast so thats all i did, i think its coming back to haunt me now...Just wanted some opinions on where i should start.
    Last edited: Dec 8, 2010
  2. plowguy43

    plowguy43 PlowSite Fanatic
    Messages: 5,264

    Your lights should be grounded to the ground post on the electric motor. This goes to the main power plug that connects to the truck (2 prong) plug and to your negative battery terminal (hopefully).

    At least my insta-act is setup this way, I can't remember if my SEHP was the same.
  3. DieselSlug

    DieselSlug PlowSite.com Addict
    Messages: 1,050

    I have an engine mounted pump with belt driven pulleys. So there is no pump on the plow, its under my hood. Not too many of these out there today. It needs rebuilding, its getting slow on idle..
  4. bob00

    bob00 Senior Member
    Messages: 143

    plow light are normaly ground by a one wire or 2 not directly to the headgear

    for a quick fix you can run a good ground to your light or even to your headgear

    or wath i did on my 2 truck is rip off the DD light connector and remplace it by a 6 way trailer plug wich works perfectly for me
  5. buddymanzpop

    buddymanzpop Senior Member
    Messages: 597

    When your plow is down and the headlights revert back to the truck go out and wiggle the plug connection at the grille and see if anything happens.
  6. DieselSlug

    DieselSlug PlowSite.com Addict
    Messages: 1,050

    I actually got the two plow lights off a truck at the junkyard, because i had the huge dorky looking ones on it, and wanted to go back to MM ones. So i think the pigtail was bad on the headlight side, becaude the old ones worked fine before. The changing is getting more sparratic, and is happening now even when the plow is up, and sometimes is happening rapidly. So for now i have unhooked the harness from my truck. Tell you the truth my truck lights seem to emit way more light than the Fisher units do. But it sucks when i have the plow up. I gotta try to get this ground wired up. Could a weakening alternator cause the issue too? I have a 6.5 diesel, and a couple weeks ago my alt died, so i did a temp fix with an alternator i had in my basement. It was for a '94 1500 350. I had to rotate the case a little and it bolted right on! But i think im running low on amps. When all accessories (well necessities when plowing) it drops to around 11-12 on the gauge. I really need to find another/ get mine rebuilt.
  7. plowguy43

    plowguy43 PlowSite Fanatic
    Messages: 5,264

    I'd get the correct altenator, the diesels require around 13.8amp's to run correctly and if your down at 10-11 your going to run into charging problem.
  8. DieselSlug

    DieselSlug PlowSite.com Addict
    Messages: 1,050

    Looking into this project now. My plan is to run an auxiliary ground from the plow frame to the truck. Been looking around for some type of good quick connect plug. Anyone have any recommendations? How large of a wire should i run?
  9. goel

    goel PlowSite.com Addict
    Messages: 1,079

    Wow. You work slower than I do. :)
  10. DieselSlug

    DieselSlug PlowSite.com Addict
    Messages: 1,050

    Yeah, last year i used the lights on the truck for the few drives i had, now i have more and would really like them to work correctly. So Friday i am gonna bring the plow out and come up with something.. Just looking for ideas.