JH kill switch screw and coil are grounded but magneto still works.

A couple customers complained that their JH magntos weren't working because the kill switch screw was grounded and/or the coil was grounded. Turns out there was nothing wrong. These JH mags simply work that way. Even so the mag dies when you run another wire from the kill switch screw to the frame. The customers just didn't see the spark for some reason. So I'm posting this vid in case someone else makes the same test and comes to the wrong conclusion.

Here's an explanation as to why the JH mag can still work when there appears to be continuity between the coil and the kill switch ground.

The Joe Hunt and Fairbanks-Morse magneto kill switch issue.

On these mags, the kill switch is tied into the same side of the coil as the points and condenser. So your meter will always show continuity there. The magneto will only shut off if that screw gets a direct, solid ground connection without the coil resistance.

The reason the meter shows continuity is because the current is going through the coil and the points inside the magneto. Most of the time the points are closed, so the meter shows almost zero ohms to ground. The small resistance in the coil is preventing the other side from grounding and allowing the mag to run.

It is the resistance of the coil that does not ground it. That has DC resistance, but is not "directly" grounded. However if you add in a solid ground connection the coil grounds out.