Ignition Coil Primary & Secondary Resistance Testing

USA Link for New Ignition coil Here http://amzn.to/1T6ftg8
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This video deals with How to test a Ignition coil on a honda gx120 but other coils maybe the same or very similar.

Primary coil resistance hook up 1 lead of the multimeter to the electrical tab and the other lead to the iron core making sure your meter is set to Ohms.

to check the secondary resistance hook up the multimeter to the iron core and inside the spark plug boot. Make sure readings are in the manufactures limits.
However I was suffering a phantom coil so sometimes this maybe tricking to figure out.
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34 thoughts on “Ignition Coil Primary & Secondary Resistance Testing

  1. Jerry, I have a question for you. I have a Craftsman leaf blower. The ignition coil, and the spark plug gets very hot and a little after I turn it off, it starts smelling to something burning and Smoke comes out fron that area. I replace the spark plug but it is about the same. I wonder if it could be the ignition coli that is worn out

  2. Does it matter if the coil is on the chainsaw or whatever? Do I set the meter on 20K? What about if the coil is older and the wires are cracked or frayed? Does that matter?

  3. Guys, remove the plug cap before measuring the secondary coil resistance as plug caps like the one in the clip are usually suppressor types ie there to suppress RF (radio frequency) noise. That's the noise or video interference you hear/see on a radio/TV etc. These type of caps are either, zero ohms, 5 K (5 thousand) ohms, 8K or 10K. You should also check the plug caps are good, ie not open circuit or more than 10K.

  4. My Echo trimmer would run for a while then die. Wouldn't re-start so I give it a 5-minute rest then it will crank again. Turns out the ignition coil was bad. After putting in a new one, it will now start every time after turning it off. I suspect something inside the coil would open the circuit when it heats up. So if yours have the same symptoms as mine if it's not the spark plug, it's the coil.

  5. Quit testing Modules with a Multi-Meter for Ohms & resistance Bologna. They either Spark or they Don't. No Spark? Disconnect the kill wire from the tab on the module, still no spark throw it away and get a new one. That simple.

  6. This is an OK test for blatantly obvious problems/resistance-problems with an ignition-coil. This is so far from a real-world test….as-in when that coil is sparking at high voltage, many times a second, you really need a scope to watch the pattern.

  7. i have a 89 ninja zx10, i have a dyna 2000 ignition on it and it has a red indicator light on it and i noticed when the light is on the bike fires up, when its not on it wont fire up. Checked my plugs and i get no spark, got a multimeter and checked coils, primary and secondary. Manual says primary should read 2.6-3.2 and it does, secondary should read 13-17 ohms. My coils are plugs 1 and 4 and 2 and 3, they both read 22-26 ohms, should changing my coils cause my bike to run again?

  8. Hi on my 08 Polaris 700 cfi on the pto side plug dose not fire when the boot is on and when I pull the boot off and hold it on the side off the plug is starts firing and runs properly and when I put the boot back on it stops firing Any ideas what's goin on there ???

  9. I installed a cheap coil (China) on my lawnboy, gapped it, etc, and it started right up…HOWEVER>> the next day it wouldn't start AND again had NO SPARK! Perhaps a "defective coil"????? I heard this could happen(Any comments?)

  10. I have a GX670 that needs the left coil to be warmed up before it will fire, indicating bad wiring in the coil that connects once it warms up. Apparently this is a common issue with many Honda small engines.

  11. Thanks for the info, I had no spark with a new spark plug on a 1978 Homelite XL chainsaw and I suspected the coil. I just checked it with a meter and came up with 2.3 ohms on the primary and no reading at all on the secondary. I even took the plug wire out of the coil and put the lead directly to it. I guess it's time for a new coil but NOS coils for this saw run about $40 and I've read bad reviews about some of the cheap coils so not sure what to buy yet…. I'm researching coils now.

  12. Hi i have a when power 2200 generator it just died on me all of a suden i pulled the spark plug and tested to see if it had spark it only sparked once or twice very week spark. If the coil is bad doesn't that mean there would be no spark at all it ran great then just died .i need it cause we got hit bad by irma

  13. @2:00 you mention coil checked good, ran a bit (mine's 20-30 seconds) then quit/died. Exactly my symptoms. Using a neon spark tester the sparks fades, ~1 second and engine dies. Repairclinic.com said most likely carb problems. (Why don't you throw my trouble shooting a curve?) I'd removed the bowl and checked it. Carb worked great while it ran. One time it kept running. 1998 Craftsman Generac 3500 watt genny.

  14. check out Ken Bohn video How to check a magneto with a flashlight battery this way it take all the guess work out coil testing, you get a spark at the spark plug!

  15. Thanks for that info at the end of the vid, I had one doing just that. The spark would go weak after 10 minutes of running, gave the symptom of losing fuel. Changing the plug for a new one which made it run for longer was was the only clue to what was wrong.

  16. Current ramp with oscilloscope with coil firing or heat gun with multi-meter only reliable test . Cold test with multi-meter is not reliable like you said

  17. can you do this test with the coil still in place? or do you need to remove it from the engine? great video btw. straight to the point. You're my kinda guy

  18. hi there i have a question for you i have echo chaisaw which i check the coil the primary give near 800 ohms and secondary 1.53 k ohms specs from says 200-400 ohms primary and secondary 1.5 to 2.2 k ohms is my coil bad ??? the saw wont start . thanks !

  19. Thanks for posting. When they do go bad,don't they usually just read open? I see a lot of guys just throw on a new one without checking continuity.

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