Enlighten me

[PTmowerMech]

i understand HOW the diode works, What i don't know is the WHY, if that wire is a ground circuit when the key is shut off, they both go to ground? What causes the back feed from one coil to the other?

I haven't read all the comments, but as you know, when one is firing, that mean the other is not. In that micro second, it could be getting juice back to it.

Now, I'll go read the other comments and see how I'm wrong.

 

[PTmowerMech]

I don't think our electrical system here uses anything like that but I would get with the FPU engineers and ask them. But getting them off their high horse is a problem.

I think they do in some places. But only on those big lines.