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Kohler Command engine harness diode

Discussion in 'Mechanic and Repair' started by piston slapper, Mar 8, 2013.

  1. piston slapper

    piston slapper LawnSite Platinum Member
    Messages: 4,335

    Just wondering if anyone has a good source for the engine harness diode on Kohler Engines..
    The newer engines with the DSAI ignition seem to eat a lot of these diodes..
    Most blow out..(open)...some short and fuse..all you have to do is touch 12 pos to the engine and it will blow...
    Heres the #'s off the diode...TC: J8 N5398
    I've replaced a bunch of them...usually robbed them from other harnesses..
    Kohler sells complete harnesses...not diodes...I already have the harness..I just need the Diode..


  2. ericg

    ericg LawnSite Silver Member
    Messages: 2,792

    Slapper check out Mouser Electronics

    tech sheet of a j8 diode
    Last edited: Mar 8, 2013
  3. piston slapper

    piston slapper LawnSite Platinum Member
    Messages: 4,335

    Thanx Eric..
    Had one of the guys go by Radio Shak and pickup 2 @ N5400 diodes for $1.98..
    A little larger..but the mower is up and running for 99 cents...and I have a spare...
    They need the mower monday morning...and they got it..the show must go on...
  4. Landrus2

    Landrus2 LawnSite Fanatic
    Messages: 5,021

  5. piston slapper

    piston slapper LawnSite Platinum Member
    Messages: 4,335

  6. herler

    herler LawnSite Fanatic
    Messages: 5,139

    These types of devices are usually supplied by electronics manufacturers and their wholesalers, dealers, and distributors.

    I'd be willing to wager, in quantities of 100 or greater...
    20 to 30 cents each.
    Maybe even less, thou I could also be gravely mistaken lol
  7. ericg

    ericg LawnSite Silver Member
    Messages: 2,792

    Herler, right on the money. $00.17 cents each in quantities of 100.
  8. piston slapper

    piston slapper LawnSite Platinum Member
    Messages: 4,335

  9. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    Slapper...... Some info for you, I've had the same repeat issue with a few machines. The diodes are blowing due to voltage spikes from disengagement of the PTO clutch.

    The fix for this issue is adding a diode to the PTO clutch plug connector;


    The new part number is 25 755 40-S, After installing this kit I've yet to see these units back with a blown DSAI harness diode.

    Fix the issue instead of milking it..... ;)
  10. piston slapper

    piston slapper LawnSite Platinum Member
    Messages: 4,335

    You know....I thought about that....
    Only had 1 problem....none of my Dixie Chopper Classics have an electric clutch....
    I have been routing the regulater directly to the battery cable...instead of thru the ignition...
    That seemed to help....thinking I might have been getting stray voltage from the stator when the magnetic field collapses during engine shutdown...
    The latest diode failure was right out of BigFishes manual...U Can't Fix Stupid..
    Much less 4 of them...The fuse holder attatched to the starter was ripped out of the engine harness..
    The Crew decided to bare that wire...loosen a solenoid mounting nut..and install it directly to the solenoid housing...:dizzy:

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