john deere757 pto clutch problem

Discussion in 'Mechanic and Repair' started by stonebridge, Jul 12, 2014.

  1. stonebridge

    stonebridge LawnSite Senior Member
    Posts: 867

    I have a john Deere 757 28hp kaw I'm not sure what's going on with it
    This is what happens I will be cutting and clutch disengages sometimes it will engage right away sometimes I have to wait a minute it will do it on one yard 2 or 3 times and maybe another lawn once sometimes it does nothing all day tired looking like a dumb ares in the middle of someones lawn
    Is this a clutch problem. Pro problem is there a relay or fuse I'm missing all connections are good
    Any help would be appreciated
     
  2. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,024

    Have the battery load tested then check for proper charging system output at the battery with wide open throttle no load......
     
  3. stonebridge

    stonebridge LawnSite Senior Member
    Posts: 867

    Just cut 3 lawns with know problems I will look up and see how to test for the load test
    What will that show me
     
  4. Restrorob

    Restrorob LawnSite Fanatic
    Posts: 11,024

    You want to take the battery out of the machine then take it to a chain auto parts store or auto repair shop, They have the equipment to test the battery to make sure it's good. A weak/faulty battery can cause the clutch to drain more power than the charging system can produce, Than can cause the clutch to randomly kick off.

    If the battery test good check the charging system as mentioned above, It should be putting 13.2 to 14.5 volts into the battery wide open no load. The higher the number without exceeding 14.5 the better.

    If the battery is good and charging system is working properly, If you have the adjustable style PTO clutch check the air gap and adjust as needed.....
     
    Last edited: Jul 12, 2014
  5. herler

    herler LawnSite Fanatic
    Posts: 5,144

    No, it's just a John Deere, that's the problem.

    I like Restro's analogy.

    I might if it were my mower, clean all the connections up real good, could be just dust got in between the connections and it's causing resistance the current can't get through, I would clean all those like down at the clutch and the battery terminals and at the PTO switch, especially since you'll be removing the battery anyway.

    But then again it is a John Deere.
     
  6. stonebridge

    stonebridge LawnSite Senior Member
    Posts: 867

    Yeah not thrilled with john Deere parts pricing but it sure cuts better than my scag vride did and it has a brand new motor on it so im gonna stick it out. With this one
     
  7. fatboyf150

    fatboyf150 LawnSite Member
    Posts: 14

    PTO Clutch

    PTO Clutch Coil Resistance 1.7-1.9 ohms

    PTO Clutch Coil Current (Minimum) at 12 VDC 7.0 A

    PTO Clutch Circuit Diagnosis

    Test Conditions:

    Machine parked on a level surface.

    Key switch in OFF position.

    Meter negative (-) lead on battery negative (-) terminal or chassis ground.

    Check connections for corrosion and looseness when checking/testing.
    System: PTO Clutch Circuit

    MIF

    (1) Battery Positive (+) Post. Measure voltage. Is voltage in the range 11.8-13.2 V?
    Yes - Go To Step (2)
    No - Check battery condition. (See "Battery Test" on page 164.)

    MIF

    (2) Starter solenoid battery terminal. Is battery voltage present?
    Yes - Go To Step (3)
    No - Check battery cables and clamps. Clean and tighten connections.

    M83143ae

    (3) Key Switch (S1) - Terminal B. Is battery voltage present?
    Yes - Go To Step (4)
    No - Test wires 220 red and 205 fuse link (F2) and connections.

    M84544

    (4) PTO Relay (K4) - Terminal 30. Is battery voltage present1?
    Yes - Go To Step (5)
    No - Test wires 240 red and 200 fuse link (F1) and connections.

    M84544

    (5) PTO Relay - Terminal 85a. Measure resistance from terminal 85 (wire 140 blk) to ground. Is resistance Less than 0.1 ohms?
    Yes - Go To Step (6)
    No - Test wires 140 and 100 black and connections.

    M84539

    (6) PTO Clutch (Y2). Measure resistance from ground terminal (wire 108 black) to ground. Is resistance Less than 0.1 ohms?
    Yes - Go To Step (7)
    No - Test wire 108 black and connections.

    M83143ae

    (7) Key Switch (S1) - Terminal A. Key switch to ON position.
    Is battery voltage present?
    Yes - Go To Step (8)
    No - Test key switch. (See "Key Switch Test" on page 170.)

    MIF

    (8) Main Fuse (F3) - Input Terminal2. Is battery voltage present?
    Yes - Go To Step (9)
    No - Test wire 400 yellow and connections.

    MIF

    (9) Main Fuse (F3) - Output Terminalb. Is battery voltage present?
    Yes - Go To Step (10)
    No - Test main fuse (F3) and connections.

    MIF

    (10) PTO Switch (S6) - Wire 460 Yellow. Is battery voltage present?
    Yes - Go To Step (11)
    No - Test wires 460 and 401 yellow and connections.

    MIF

    (11) PTO Switch (S6) - Wire 500 Blue. Is battery voltage present?
    Yes - Go To Step (12)
    No - Test PTO switch. (See "PTO Switch Test" on page 172.)

    M84539

    (12) PTO Clutch (Y2). Is battery voltage present?
    No - Test wire 510 blue and connections.
    1

    When checking voltages and/or resistance at relay terminals, it is necessary to disconnect the relay connector and check voltages at the open terminal. Reconnect the wiring connector after performing the check.

    2

    When checking voltages and/or resistance at the main fuse, it is necessary to remove fuse cover and check voltages at the exposed terminal. Install the cover after performing the check.
     
  8. fatboyf150

    fatboyf150 LawnSite Member
    Posts: 14

    PTO Clutch Circuit Operation
    Function

    To provide power to energize or de-energize the PTO clutch and/or MCS (Material Collection System) clutch when desired by the operator.
    Theory of Operation

    The power circuit provides current to the key switch (S1) and protects the PTO circuit with fuse link (F2). Current flows from the battery (G1) positive (+) terminal to the key switch (wires 205 fuse link [F2] and 220 red).

    With the key switch in the RUN position, current flows to 20-amp main fuse (F3) (wire 400 yellow) and PTO switch (S6) (wires 401 and 460 yellow). Current flows directly to PTO relay (K4) terminal 30 from the battery (wires 200 fuse link and 240 red).

    With the PTO switch in the ON position, current flows to the coil of PTO relay (K4) (wire 500 blue). A path to ground (wire 140 black) completes the relay coil circuit, engaging the relay.

    With the PTO relay engaged, current flows across the relay contacts to PTO clutch (Y2) (wire 510 blue). A path to ground (wire 108 black) completes the circuit engaging the PTO clutch.

    757pto.jpg
     
  9. fatboyf150

    fatboyf150 LawnSite Member
    Posts: 14

    PTO Switch Test
    Reason

    To verify that the continuity between terminals is correct when the switch is in the ON and OFF positions.

    Special or Required Tools

    Tool Name


    Tool No.


    Tool Use

    Ohmmeter or Continuity Tester


    NA


    Used to test continuity between terminals.
    Procedure

    1. Park machine on level surface.

    2. Turn key switch to OFF position.

    3. Engage park brake.

    4. Remove right-side control console cover.

    5. Disconnect PTO switch connector.

    6. Move PTO switch to OFF position.

    M47616

    7. Connect ohmmeter leads to terminals (A and B). There should be continuity.

    8. Connect ohmmeter leads to terminals (C and E). There should be continuity.

    9. Move PTO switch to ON position.

    10. Connect ohmmeter leads to terminals (D and E). There should be continuity.
    Results

    If continuity is not correct, replace switch.

    757pto2.jpg
     
  10. stonebridge

    stonebridge LawnSite Senior Member
    Posts: 867

    Last month I put a new 28hp law to replace the 25hp law there were 2 wires that I didn't get used the long green and long yellow on the starter side that went to the volt regulator the new motor only had one prong for the red connection could that be part of the problem
     

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