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Uni MVP wiring help needed... iso mod conversion

Discussion in 'Western Plows Discussion' started by x.system, Nov 20, 2011.

  1. x.system

    x.system Senior Member
    Messages: 368

    Got a customer who brought me a mvp with an iso mod conversion (4 port PN 27779) and they couldn't get it to work. I can't find a wiring diagram for this setup. There is a small wire on the power plug (plow side, 3 pin) that is cut and I need to know where this goes if anywhere. They also had a jumper wire from the top 3 coils going to positive side on the motor. I disconnected this and wanted to start over.
     
  2. 06Sierra

    06Sierra PlowSite.com Addict
    from Maine
    Messages: 1,328

    I believe the wire from the coils goes to ground on the motor. On the harness from the iso, there is a small wire that goes to the solenoid and another that goes to pos on the battery not sure if that is the wire you are talking about. If no one else has replied by this afternoon, I will dig up the wire diagram. I know I have run across it before.
     
  3. x.system

    x.system Senior Member
    Messages: 368

    I found a few pages I printed off. It looks like the relay style harness (plow side power) has the small red wire and the iso mod harness does not, sound right? I need a new plow side power harness regardless so I need to know which one is correct for the iso mod. I think the only diagram I can't find is the plow side wiring for iso mod setup.
     
  4. 06Sierra

    06Sierra PlowSite.com Addict
    from Maine
    Messages: 1,328

  5. 06Sierra

    06Sierra PlowSite.com Addict
    from Maine
    Messages: 1,328

    Looking around on Fisher's site, that 3 pin plug should be a 7 pin for a V. 3 pin is for straight blade.
     
  6. x.system

    x.system Senior Member
    Messages: 368

    Page 52 looks like a relay style harness, looks just like my MVP that has relays still. This other one doesn't have those ground wires coming out of that harness. I messed around with it some more and the motor runs on every function but nothing is happening, no movement. I'm thinking its a ground issue but can't find the problem.

    I have a seven pin for the lights, not a three.
     
  7. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    You need to wire it like an Ultra MVP non plus model three plug system. Page 36 here.
     
  8. x.system

    x.system Senior Member
    Messages: 368

    Thats the diagram I printed out, Do the lights have to be hooked up in order for this system to work? I've got the headlight harness plugged in but havn't tapped into the lights yet. I'm getting all the lights to work on the controller, the motor runs if I hit the button but no movement from any of the cylinders.

    I checked the motor relay. and its showing power on the battery side and both small posts weather the controller is on or off, that doesn't seem right.
     
  9. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    The headlamps don't have to be wired but the grill plug for them needs to be plugged in to complete the ground circuit, which you obviously have if you have the pump activating.

    However you also have to be sure the red/yellow (truck side) and red (plow side) on the #6 pin has power on both side of the grill plug for the coils to work, otherwise you'll have pump activation but no plow functions. If you're not aware, all the coils have 12V supplied at all times, they're actually activated with ground. Opposite of what you're probably accustom to.
     
  10. x.system

    x.system Senior Member
    Messages: 368

    Thanks B&B, you nailed it again! Had power at the iso mod red/yellow but at the plug it was dead. Changed out the #1 harness and everything worked as it should.