snowhound 105 #1 Posted October 28, 2023 416-8 with a Kohler M16 doesn't turn off. I've replaced the ignition switch, checked that the iginition switch is grounded and checked the kill wire for continuity and all are good. The kill wire has a diode so when i checked the kill wire I ckecked it without going through the diode. My question is could the diode cause it not to shut off. 1 Share this post Link to post Share on other sites
Gasaholic 224 #2 Posted October 28, 2023 You sure it's a magnum? Yes a bad diode can cause open circuit condition - I don't believe diode would have been original, but may have been installed by someone wanting to protect against a 12v bleed to the magneto coil (which would destroy the coil) if you are sure that is a diode, easy to test them with a multimeter (diode/ continuity scale - a diode should show continuity only one way - but they can fail open and have open circuit both ways.) If I saw a diode in a Magnum magneto ignition , I'd be checking the switch and wiring (Wrong switch maybe? ) to see if it showed 12 volts at ANY point in the ground wire wiring, if it did, then I would be investigating the reason why (Shorted wire in harness? mis-wired harness? failed or wrong switch?) If it showed 12 volts at any condition on the magneto ground wire, that would likely explain why someone installed a diode. (a cheap bass-ackwards fix) Share this post Link to post Share on other sites
snowhound 105 #3 Posted October 28, 2023 Gasaholic - Thanks for the reply, I'm sure it is the correct switch and wiring diagram I have shows the diode as being optional. I will test the grounding wire for voilage and the diode to see if it failed. I will also recheck the wiring harness. Share this post Link to post Share on other sites
Rick3478 428 #4 Posted October 28, 2023 1 hour ago, snowhound said: 416-8 with a Kohler M16 doesn't turn off. I've replaced the ignition switch, checked that the iginition switch is grounded and checked the kill wire for continuity and all are good. The kill wire has a diode so when i checked the kill wire I ckecked it without going through the diode. My question is could the diode cause it not to shut off. Are you sure that's the kill wire? I can't think of a reason for a diode in the kill wire. Some of the low charging versions of the motor may have the stator charge current coming out through a single diode, and grounding that will not kill the ignition. Did someone swap engines and try to use the wrong wire for the ignition kill? Share this post Link to post Share on other sites
gwest_ca-(File Mod) 11,072 #5 Posted October 28, 2023 Common to use a diode in the ignition wire to prevent battery power from accidently reaching the ignition module which releases the magic smoke. Suspect the diode may have taken a hit and is now open. Easy to check with an ohmmeter. Illustration from the Kohler service manual. 2 1 Share this post Link to post Share on other sites
953 nut 55,394 #6 Posted October 28, 2023 3 hours ago, gwest_ca said: Suspect the diode may have taken a hit and is now open Several decades of heat and vibration could have caused the diode to fail. Share this post Link to post Share on other sites
