I have a hedge trimmer I'm troubleshooting (link) and I'm wanting to rule out the ignition coil. What resistance should I measure across a typical small engine ignition coil? I would have thought down around 50 ohms or less, but I'm measuring up in the Kohms.


1 Answer 1


It typically depends on the model but 50 ohms across the positive wire post and the spark plug wire post would indicate a problem. While I can't definitively answer what range your specific coil should read, it would typically be good to see an automotive coil read ~10,000 ohms for this check.

Where you would see a low resistance is across the primary winding. That would be the positive wire and the negative wire posts. This should read a negligible resistance, think 0-10 ohms (give or take).

  • I must have been reading the secondary when I got the kohm reading, which means I'm in good shape. Good to have that ruled out. That, and the fact that it is putting out sparks gives me peace of mind to move on. Thank you. Sep 21, 2011 at 22:49

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