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1985 Champion 720A - will not engage in F or R

Discussion in 'Motor Graders' started by Monte Nelson, Aug 10, 2019.

  1. Monte Nelson

    Monte Nelson Member

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    Location:
    Ellsworth County, Kansas
    The 720A Motor runs (when you bypass the neutral safety relay) and the hydraulics work but when you engage to move forward or reverse the grader doesn't move.
    I have replaced the following:
    Neutral safety switch and relay
    Checked with ome meter all transmission cartridges and replace one with dual plugs that was reading bad.
    Ignition switch
    I'm located in Ellsworth Co. Kansas and cannot find anyone to make a service call? Please help if you can. Thanks
     
  2. laycobeau

    laycobeau Well-Known Member

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    Is this an 8400 trans if so is the two digit display lit between the two levers if so what is the error code?
     
  3. DB2

    DB2 Senior Member

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    Good advice

    Also check voltage.

    And there is a micro switch on the shifter that can fail and not give any codes
     
  4. laycobeau

    laycobeau Well-Known Member

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    If it fails you get no power to the shifter or solenoids.
     
    DB2 likes this.
  5. Monte Nelson

    Monte Nelson Member

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    Yes it is. Thanks for your help. The error code was E 4.2. I checked the manual and it stayed neutral safety switch. I have replaced it and checked voltage as well as the neutral safety relay.
     
  6. Monte Nelson

    Monte Nelson Member

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    Ok thanks!
     
  7. Monte Nelson

    Monte Nelson Member

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    Thank you! I checked voltage on new replacement switch and changed it out as well. Still no luck. Thank you
     
  8. DB2

    DB2 Senior Member

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    Make sure alternator is putting out proper voltage is what I was referring to.

    Low volts and she won’t go.
     
  9. Monte Nelson

    Monte Nelson Member

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    Thank you. I just put a new one on it reads 12 volts when engine running.
     
  10. DB2

    DB2 Senior Member

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    What year or series is your machine?
     
  11. DB2

    DB2 Senior Member

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    Have you checked that the drive shaft between the engine and transmission keeps turning when you engage the transmission ? Perhaps the clutch is slipping
     
  12. Monte Nelson

    Monte Nelson Member

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    Location:
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    1985 720A
     
  13. DB2

    DB2 Senior Member

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    Should read about 13.5 volts running but 12 should be enough to get it to engage
     
  14. laycobeau

    laycobeau Well-Known Member

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    Are you still bypassing the neutral start relay to start this unit? If you are you have something wrong in your key switch wiring. If it does not get a neutral
    signal when powers up it will give you that error.
     
    DB2 likes this.
  15. RoyfromOz

    RoyfromOz New Member

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    Location:
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    I have a similar issue today with my 720A series 3. Sometimes in the past, when I went to shift into reverse, it stayed in neutral and took a few attempts to get the selector to engage reverse. It was an intermittent thing, only occurring occasionally. However, yesterday it got worse and now it won't select forwards or reverse. The LED gear indicator alternates between the forward gear and the reverse gear numbers, as usual when in neutral, no error codes. The speed selector appears to be able to select higher and lower speeds, according to the gear number indicator, and that has been working most of the time (sometimes you get an attempted upshift that doesn't happen, but next time it works). Also, the engine will start, even if the direction selector is in forwards or reverse, which i assume it shouldn't.
    We checked the operation of the micro switch on bottom of the selector box and it does seem to be a bit faulty, sometimes not switching, but most of the time it did switch. So we thought it should work the trans (at least on most attempts to shift) well enough until we get a new micro-switch, however it still won't shift at all.
    Should we check something else now, or just wait to see if the new switch fixes it alone?
    Thanks.
     
  16. Monte Nelson

    Monte Nelson Member

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    Great info similar to my issue. I have replaced the neutral safety switch and still have the same issue? Great info and thanks.
     
  17. Monte Nelson

    Monte Nelson Member

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    Thank you. I not a wireing expert but it looks like I need to reach out to that person. You have been a great help thanks again!
     
  18. Monte Nelson

    Monte Nelson Member

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    Location:
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    Yep your right it is over 12 volts and close to 13. Thank you