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Unimount Light/ pump problem

Discussion in 'Western Plows Discussion' started by RCsLawncare, Mar 2, 2014.

  1. RCsLawncare

    RCsLawncare Senior Member
    Messages: 459

    I went ahead and put on a new electric pump on my plow and didnt change anything else but now when the plow lights come on, the elecric pump motor begins to spin until I unhook it. Iv searched and cant find anyone else with the same problem. I thought it was the relay by chance and swapped it out with a new one, still same problem. Iv had the plow 3 years on two other trucks and it hasn't ever done this, anyone else seen this? The truck it is on is a 1998 GMC K1500. I appricate the info.
     
  2. mishnick

    mishnick 2000 Club Member
    Messages: 2,243

    Not sure what kind of plow this is but it sounds like the lights r finding ground through the motor. If my suspicions r correct about the generation of plow....
    There r two big cables on the pump motor and one small one. The smaller wire is black with an org tracer. It should b on the negative lug.
     
  3. mishnick

    mishnick 2000 Club Member
    Messages: 2,243

    Do all the plow functions work normally? Like angle, up and down. This is a straight blade right? Still has the original two plug system with relays, has not been upgraded to three plug with isolation module?
     
  4. RCsLawncare

    RCsLawncare Senior Member
    Messages: 459

    Hey there, I appriciate the responce. It is a 8ft Unimount Straight pro plow and does have the 3 wires, 2 big and the black/ orange that is on the ground on the electric motor. It is still a 2 plug system with 2 relays for the headlights. Im not sure how to go about fixing it since I literally just replaced the pump. I dont know if its possible to have the ground and positive backwards as I just went off the old style motor how the were on it. Would the motor still function ok with the two large wires reversed? The positive is mounted higher than the ground and the little wire is with the ground wire on the motor. And the motor worked fine, no problems actually fuctioning like it should.
     
  5. mishnick

    mishnick 2000 Club Member
    Messages: 2,243

    That motor can't turn the wrong way unless it was miswired at the factory. Unlike permanent magnet motors that are reversible, your motor has electric magnets and electric armature so when the polarity is reversed both magnetic fields are reversed negating the polarity change. In other words, this motor can't spin the wrong direction.
    I have to ask what you mean by changing the "electric pump?" There is a mechanical gear pump inside the pump assembly and then there is an electric motor, that drives the pump, mounted on top of the pump / valve body assembly. Did you change the pump or the motor?
    It still sounds like you have that small black / org wire connected to the wrong side of the motor. Perhaps the motor lugs are not marked + or -. Look at the color of the large cable. The positive wire coming from the grill plug will be red or black with a red line while the negative will be solid black. The small black / org ground wire should be connected to the large negative cable, the solid black one.
    Having looked at the schematic I see why your functions are OK. MVP has a common + going to the valve coils and does not use the common ground on the motor like the straight blades. Your motor power plug at the grill has a three pins, two large (+ and -) and then a small one that feeds ignition power to the coils full time when the key is on.
    Never the less I am even more convinced that small black / org wire at the motor is on the wrong lug.
     
  6. RCsLawncare

    RCsLawncare Senior Member
    Messages: 459

    Sorry for the confusion, It was only the electric motor. And It is not labled, i will switch them around and see if that yields any difference. I appriciate the great info on it and reasoning. Ill upate tomorrow when I go out and work on it. Thanks again.