This is a video of the coil or armature magneto being replaced from a Briggs and Stratton 12HP Lawnmower engine. They can also be called an Ignition module or Ignition coil. If you are not getting spark in your spark plug, this might be your answer. If not, check all your safety button switches too. Also, symptoms of the mower not staying running or stopping after heating up can be the armature magneto too.

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  1. I just finished fixing a problem that drove me wild for a few days. No spark….hmmm. Removed the cover. Cleaned the coil where it mounts to the case with sandpaper to ensure a good electrical connection. I also sanded the flywheel until it was clean and free of dirt and rust. Reassembled everything and still no spark. Being it was only a flywheel and the coil I assumed the problem was the coil. I ordered the OEM Briggs coil from Amazon ($30). I installed it and still no spark…aaarrrggghhh!!! I finally had an idea that I hadn’t thought of…..disconnect the grounding wire that is attached to the little tab on the coil. I pulled that little spade connector off and reassembled the cover and viola. It started and ran. I couldn’t believe it. I chased this problem for days only to find out that the safety mechanism that grounds out the spark when the handle is released was the cause of the problem. It was permanently disabling (grounding out) the coil whether the handle was pulled in or not. Moral of the story…..when chasing a no spark problem and you’re down to the coil disconnect the spade lug at the coil in order to omit that as a possible cause.

  2. Thank you. I may have the same problem on my 3 mowers. None want to turn over, make a clicking noise. I often get overwhelmed with the 'simplicity' of repairs because of not knowing trouble shooting methods.

  3. Great job, but one thing you may not realize is measurements.  I'm not trying to be a smart ass, but most people don't know this…  when you said the business card is .010 of an inch, that is "read" as ten thousandths of an inch, later you mentioned that you can use a tool and set it at .030, which is thirty thousandths of an inch.

  4. You really need to verify your results. Did you have spark after you were done? I guess we will never know…:p(

  5. Most of time coil not broke.
    But rust on flywheel magneto and coil causes coil not to charge. Take apart-clean flywheel and coil for rust(sandpaper) -blow away -put coil back-voila works again -no dollars for spares.

  6. question: i have a 3hp B&S and and i have no spark, one wire goes from the coil to the points, one to the sparkplug but i dont know where the third wire has to go.

  7. I replaced the coil on my rototiller and it still had a problem starting even with starting fluid. Idk what the odds are of getting a defective or weak coil, but I would think it happens. This videos etc. of different tests such as primary and secondary resistance tests.

    On a search, I found a Briggs and Stratton site that mentions some of the troubleshooting and the " myths" about the tests and conditions.

  8. here's my problem… I have a cub cadet zero turn…I just replaced the ignition module a little over a month ago… well just a couple weeks ago I was on a job site and shut the mower off to fill it with gas… I went to start it back up… no go… so I jumpered out the solenoid and that started it up… I did that for about a week hoping to finish out the season and then working on it… well after a week, jumpering out the solenoid no longer worked… I replaced the solenoid… replaced the starter… checked and cleaned the carburetor… I turn the key and nothing… however when I turn the key and jumper the solenoid it'll crank but no fire… could this be caused by the magnetos? I've been pulling my hair out over this… we've gone through all of the electrical and the magnetos are the next step and pretty much the only thing we haven't checked yet.

  9. After watching your video I was able to confidentiality replace my coil but the B&S 625 Series engine still will not start. I replaced the carburetor, primer pump, governor spring, control bracket, changed oil, replaced the gas, new spark plug and replaced air filter. I even tried starter fluid on it. Any ideas about why it still doesn't start? Is there a fuel filter somewhere? Thanks

  10. Thanks for the simple fix. I do believe this is my problem. I already ordered the coil and now I can replace it with confidence. I was a little concerned about the spacing but the card hack is what I needed. Thanks and God bless you. JAH

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