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Gravely Promaster 20H Blown Fuse

Discussion in 'Mechanic and Repair' started by neversink, May 27, 2007.

  1. neversink

    neversink LawnSite Member
    Messages: 4

    Fuse between the ampmeter and hot side of the solenoid will burn out after 15-20 minutes of mowing. Then, it will blow a new fuse within minutes if you replace it immediately. Any ideas?
     
  2. khouse

    khouse LawnSite Bronze Member
    Messages: 1,465

    Is the fuse the correct size?
     
  3. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    Check the positive power lead (red) on the back of the ignition switch for rust/corrosion. If rusted the contacts inside are most likely burnt/shorted, Replace the switch and red connector.
     
  4. fixer67

    fixer67 LawnSite Silver Member
    Messages: 2,098

    Also check the fuse holder. If the holder has rust/corrosion it may not hold the fuse tight and cause it it heat which will cause it to blow at a lower amp load than it should. A 20 amp fuse can blow at 10 amps if the fuse gets hot. This is called "cooking". When a fuse cooks it damages the holder even more until it is totally useless.
     
  5. neversink

    neversink LawnSite Member
    Messages: 4

    All connections are rust free. The fuse size was a 20 amp fuse. I bought this mower used, so I'm not sure of the fuse size for sure. I have tried 15, 20, 30 amp fuses. I can't find a wiring diagram for this ZTR mower
     
  6. Bill Kapaun

    Bill Kapaun LawnSite Senior Member
    Messages: 944

    Did the 20 & 30 amp fuses take the same amount of time before they blew?
    What I'm thinking, is IF they did, it's a heat related issue. Something starts drawing excessive current when it gets hot or something "moves", causing a short. Just what "heat related issue", I don't know.

    DOES the ammeter start showing increasing current flow before the fuse blows?
     
  7. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    If I had full model and serial numbers off this unit there's a good chance I may be able to drum up one.

    Does this one have the Kohler or Onan ?
     
  8. neversink

    neversink LawnSite Member
    Messages: 4

    Promaster 20H, s/n 00633259, 60 in. deck, Kohler MV20S (57513)
     
  9. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    Here's the wiring diagram.....

    You may try by-passing the ammeter by connecting the pink/black and white/black together, I have seen ammeters short out.



    [​IMG]
     
  10. neversink

    neversink LawnSite Member
    Messages: 4

    Thank for your help. I'll let you know what I find.
     

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