Scag / Kohler has me stumped

Discussion in 'Mechanic and Repair' started by AlohaMowing, Sep 9, 2011.

  1. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029


    I see now that you do have the SAM ignition system on this engine, I haven't seen a test procedure for the twin cylinder SAM other than the fancy test tool listed in the manual.

    But, You can use the single cylinder SAM test as a guide since you can't find anything on the other;



    The modules will still be in question since the kill circuit test is out of recommended specs......
  2. AlohaMowing

    AlohaMowing LawnSite Member
    Messages: 58

    The only diode on the machine seems to be the one combined with a relay and which I have already replaced. The Scag wiring diagram does show a second diode between the negative terminal of the hour meter and an unspecified point on the engine, but the parts list does not show that second diode, and I have not seen one. The Kohler wiring diagram and parts list show no diodes at all.
  3. AlohaMowing

    AlohaMowing LawnSite Member
    Messages: 58

    Restrorob - Thanks for all your efforts. Step 4 of the troubleshooting procedure gives me pause. There is not enough clearance to remove the blower housing without first removing the engine from the mower.

    I have done a jumper wire test putting 12v to the connector that feeds the ignition components, thus bypassing the switch and all circuits on the Scag side of the connector. The engine runs so long as I keep power on that. I think this narrows down the problem to the Scag side, and I'm going to jury rig it with a jumper to get some desperately needed mowing done. But the fix still eludes me.

    The wires on the Scag side of the connector are all well-protected and there is no visible damage. I have to suspect the problem is in the Scag-side electronic module, part # 483029, which interconnects the ignition switch, safety switches, diode and relay, but really don't want to spend over $100 for a new one unless I'm sure it's bad. I have been unable to find an online service manual for the Turf Tiger. Anyone have any thoughts on how to test the electronic module?
  4. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    If you can't find a procedure/specs as I haven't been able to on other brand units test everything else, If everything else test good the only thing left is the module.

    There should be a wire coming out of this module going to a ground point (frame etc.), Remove the ground wire and try starting the engine. If it now starts and all safety switches test good with a multimeter on ohms scale, Replace the module.....
  5. AlohaMowing

    AlohaMowing LawnSite Member
    Messages: 58

    Oh, man, do I ever feel foolish, but I have learned something: Never trust a visual inspection to determine that a fuse is good.

    The first thing I had checked when the mower stopped was the fuses. They both looked good. After having done the jumper wire test I put a multimeter on the fuse for the ignition circuit. No current was getting through it. It still looks good, but I replaced the fuse and the mower now runs.

    So, a visual inspection may tell you that a fuse is blown, but don't trust it to determine that a fuse is good.

    I sincerely thank everyone who offered up comments and suggestions, and especially Restrorob.

    A new problem has surfaced, but hopefully I can sort it out myself. Again, thank you.
  6. Restrorob

    Restrorob LawnSite Fanatic
    Messages: 11,029

    Well.....When I look at a work order and see electrical issues (won't start etc.) stated, The first thing I grab is my trusty test light. Pulling a fuse looking at it then putting it back in is wasted motion, Test light probed in each slot on the back of the fuse will show it good or bad......

    Good to hear you got er sorted out ! :clapping:
  7. scagwildcat

    scagwildcat LawnSite Senior Member
    from nw. ct.
    Messages: 507

    i had the same thing happen to me., fuel looked good, switches good, couldnt figure it out, in the end i spent weeks looking my mower over, and all it was ,was a bad fuse holder that would not allow proper fuel to the carb, as soon as i would hit a bump the machine would stall... now the first thing i do is check fuses and holders....
  8. piston slapper

    piston slapper LawnSite Platinum Member
    Messages: 4,337

    ALOHA....glad you got it fixed...

    FYI....There are 2 diodes in the factory engine harness, 1 for start circuit,1 for run circuit. They are not listed in any diagrams....They are there....
    Some newer engines only have 1 diode which is causing some other issues.

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