John Deere 757 not charging electrical

Discussion in 'Mechanic and Repair' started by BryanStein, Sep 30, 2012.

  1. BryanStein

    BryanStein LawnSite Member
    Messages: 37

    2006 Kaw 25 hp FH721D engine.

    Just replaced stator, voltage regulator, and coils(they looked bad). Alt light still on. Alt light used to turn on only when clutch was engaged. Now its on whenever its running. I think it was off because the battery was brand new

    If I run it for 2 minutes the stator leads get really hot. If I run it an hour, the stator leads melt. That is why I went ahead and replaced the stator ... The leads were melted.

    Stator output is 37 V AC. Battery voltage is 12.6 at idle and at speed. Not sure if wiring is hioked up correct. Anybody got a picture of the wiring harness connection on the right side of the engine while looking at it from the back? It would be appreciated. My wiring plugs are damaged so I can hook it either way.

    There are three prongs on the VR. I have the two stator leads connected to the two prongs that are connected, and the hot lead connected to the other. This had to be correct doesn't it?

    I will do more checking with the volt meter today. I think I've got a short somewhere that its causing the vr not to function

    Restrorob, do you have that wiring diagram in a higher resolution? It tells me tons more than I knew before getting it (thanks again), but I can't read some of the colors and numbers.

    Thanks for the help.
    Posted via Mobile Device
     
  2. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,001

    Here goes......

    [​IMG]


    [​IMG]



    [​IMG]
     
  3. OP
    OP
    BryanStein

    BryanStein LawnSite Member
    Messages: 37

    Posted via Mobile Device
     
  4. OP
    OP
    BryanStein

    BryanStein LawnSite Member
    Messages: 37

    Rob, you are my new hero. The VR was wired wrong. Two off the leads coming out of the vr are connected together before they are shaped to two sepereate plugs or prongs. When I got the mower, both stator leads were connected to these two leads. My new vr came out of the box with one of those connected leads bent to accept the hot wire, because it was different than what I had, I bent the lead down to parrallel with the other to accept the dual stator leads.

    When I saw your diagram of the vr, it made me thing about changing it, so I did. I now have 14.6 volts across my battery at idle and at speed. Its 12.4 volts with the engine off. I thougt (and the book said) the voltage should increase at higher rpms. Maybe the vr is regulating it down to 14.6 at all times.

    It still doesn't make sense to have the hot wire connected directly to one of the stator leads before our goes into the vr.

    I also now have a good wiring diagram fire the mower.

    Thanks again.
    Posted via Mobile Device
     
  5. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,001

    Well,

    You need to either forget about how who ever had it wired and wire it like the diagram shows, Or get the proper voltage regulator for your application.

    It shouldn't be charging 14.6 at idle......



    http://www.youtube.com/watch?v=a527ZOSJ0rY . :drinkup:
     
    Last edited: Sep 30, 2012
  6. OP
    OP
    BryanStein

    BryanStein LawnSite Member
    Messages: 37

    I have it wired like your diagram shows .... which is different than when I got the mower.

    Brand new vr from the local john deere store 15 miles away. Why is charging at 14.6 volts bad for a battery that is about half charged? The book says it could charge you to 15 volts at speed.

    Did I fry my vr by having it wired wrong?


    .
    Posted via Mobile Device
     
  7. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,001


    Ahhh...... You said....


    That's not a half charged battery, That's close enough to a full charge.

    Put the battery on a charger on slow charge for a few hours then let it sit for a couple hours (removing surface charge) then test again......

    And yes..... It's possible to blow electrical components hooking them up wrong....
     

Share This Page