Olratlr 25 #1 Posted July 20, 2012 I have a 520H I am not getting any fire from the coil will turn over fine but will not fire will not turn over unless on seat so I guess seat safety switch is working any help is appreciated. Norm Share this post Link to post Share on other sites
Save Old Iron 1,563 #2 Posted July 21, 2012 Hey Norm, try this. Connect a test light to a chassis ground. Touch the probe end of the test light to the positive (+) terminal of the coil. Turn the ignition key to the RUN position. If the test light is not lit, verify you have a good ground for the test light (touch the probe end of the test light directly to the battery (+) terminal - the test light should be on full brightness). If the test light is still off, check for a bad connection between the coil and the key switch. The 9 pin connector could be a suspect. Once you have voltage at the coil (+) positive terminal, crank the engine. The test light should stay on. If the test light is interminttently on, check the ignition switch or wiring to the ignition switch. Connect the test light to the negative (-) terminal of the coil. Crank the engine. The test light should pulse on and off while the engine is cranking. If the test light does not pulse, suspect the ignition module. If the test light does flash while cranking, check / replace the coil, spark plug wires or the spark plugs. Share this post Link to post Share on other sites
Olratlr 25 #3 Posted July 22, 2012 Thanks! I know I am getting fire to the coil but none coming out of coil. The last time I mowed the Tractor backfired real loud and quit running while mowing it started back up and I mowed two hours with it. The next week it want start. I will try what you said. Thanks Norm Share this post Link to post Share on other sites
Save Old Iron 1,563 #4 Posted July 22, 2012 Thanks! I know I am getting fire to the coil but none coming out of coil. If it restarts after a cool down period, the coil is the most likely culprit. Be aware the Onan coil also has a condenser attached to the (+) side of the coil (I believe). An ohms check on the primary and secondary of the coil when the tractor stops will confirm if the coil is failing. Good luck. p.s. As I run this scenario thru my head, I tend to believe a test light MAY NOT flash on the negative coil terminal IF THE COIL PRIMARY IS OPEN. This particular scenario could lead to some confusion when using a test light to troubleshoot. A multimeter OHMS check would pick up the issue with an infinite resistance reading showing between the coil (-) and (+) terminals. Just one of those "special circumstances" when using a test light to troubleshoot. Share this post Link to post Share on other sites
ericj 1,576 #5 Posted July 23, 2012 the onan manual gives you all the voltage readings and ohms readings you need and also a step by step directions to do so. you should be able to get a manual on line or possible here if not pm me and i can email it to you. eric Share this post Link to post Share on other sites
