Mower runs, but magneto/spark plug is grounded even when brake handle is pulled. Why?

[Rivets]

You don’t understand what I’m saying. I’m chasing my tail trying to explain how the kill circuit on a small engine works. That being said I’m getting out of this thread and hopefully someone can explain it better than I can.

 

[Grounded]

You don’t understand what I’m saying. I’m chasing my tail trying to explain how the kill circuit on a small engine works. That being said I’m getting out of this thread and hopefully someone can explain it better than I

You have explained it. I was already familiar. I'm looking for the answer to a specific question that is not being answered by your explanation.

 

[stihlmania]

You have explained it. I was already familiar. I'm looking for the answer to a specific question that is not being answered by your explanation.

To test the primary circuit of your coil, one lead of multi meter to coil mount, one lead to primary connector, (ground connector wire unplugged) you should have continuity, Or ground as you call it.

 

[Oddjob]

So Grounded, it appears to me that you have a perfectly operating mower with a kill switch that works when you release the brake/bail lever. Is that right? If so, this isn’t a problem, it is you pondering why your kill switch is working. I suggest you google “how does a kill switch work on a lawnmower?” There are some really good videos out there that explain it better than I can. But, if you want the short-cut, not scientific, answer, here’s how I think of it. The kill wire on the magneto is like a lightning rod. Its function is to divert the electricity that the magneto generated from going to the sparkplug. It won’t divert the energy unless there is a clear path for the electrons to follow to ground. That path is via the kill switch.

 

[Joed756]

Yeah, I understand that. That's why I'm confused about there being continuity between kill switch contact points when the kill switch is open. That would suggest the coil circuit is grounded whether the kill switch is open or closed, which doesn't make sense given that the mower starts and runs. Maybe have another read through my initial post to see the tests I did with the multimeter.

"the mower starts and runs."
You are looking a gift horse in the mouth.

 

[STEVES]

take an ohm reading of each, some coils have (the kill wire) have a low ohm reading, where kill side (ground) is 0 (ish)

 

[12icer]

So is it your idea the mower should not run anytime the brake is released?

The Brake kill is to prevent starting when the brake is off just as if you are not seated or the blade is engaged.

Depending on the mower it may have all or only one of these safety switches.

If you ground the coil primary before the contacts or the exciter or block the signal from the primary winding it will not run, If the signal passes through the primary circuit it will run simple as that any path that completes the primary circuit AFTER IT goes through the pulse will induce spark.

A dead kill switch grounds the signal before it reaches the coil winding.
A primary switch kills the direct current before it reaches the points or pulse inducer.

 

[STEVES]

ohm reading contact point, magneto side, to ground at block / ohm reading contact point, ground side, to ground at block / all with bale pulled / different or same?

 

[StarTech]

These ignition coils will read shorted using a continuity checker. This is because the primary winding is 1.5 - 1.7 Ω. When the kill switch is closed then it becomes a dead short
(zero Ω or near zero as the wiring has a little resistance).

 

[STEVES]

Yes, hoping to answer 'Grounded', (Again, the mower runs. But I don't understand why, and I would very much like to know. Thanks.)