Is the transistor case 'hot' with the engine running? I was under the impression that this was connected to coil neg, so 200-300v back EMF. Have not been brave enough to stick my finger on it to find out...
The coil is fed by switched and ballasted battery voltage.
AFAIK the ECU is just an amp and a translator for the magnetic pick-up, and the transistor is like a glorified set of points, being a fast-acting ground-interrupter. I can't see how anything over battery voltage can come out of the ECU, and I can't even see how any voltage at all could go into the coil.
The box just needs a ground for translator/amp that turns the magnetic trigger into a signal shape with enough strength to turn the transistor on and off. Oh yeah and a ground for the coil primary side, lol.
Buy what do I know, lol.
