There’s power on the heavy red and ground on the heavy black….

Red switched to 12v is getting 12v w key on. Black to coil tests good for ground…

Orange however is not putting out 12v.

Does this mean switch out MSD…? How does this even happen…?? It’s been FINE for years.

Usually starts right up even in the cold. This time it sounds like it kinda wants to start but wouldn’t.

Checked for spark and trailing does have spark which is hooked up in stock configuration thru stock distributor off a MSD blaster coil.

Leading which is hooked up thru MSD 6a has no spark or 12v on + of MSD blaster coil or Orange off of 6a.

 

Could be the magnetic pickup in the dizzy for leading not putting out a good signal to the MSD. How did you get the pickup from the dizzy to the MSD? Modified the ignitor?

 

I was thinking that after posting. That’s why I post sometimes to kind of think out loud. I did change the battery and then this happened, coincidence, usually never lol. Maybe I knocked something loose by moving the positive harness. I’m pretty sure the signal wires off the leading distributor is wrapped in there w butt connectors somewhere along the line. Will report back.

 

Haha! Yeah, see you did touch something. Old cars are fun that way!

 

Does the orange put out 12v off distributor signal tho…? Shouldn’t the coil at least have 12v constant from orange once the 12v switched / keyed / small red is applied…?

 

The signal from the dizzy is a very low voltage waveform that gets generated by the reluctor on the dizzy rotating past the pickup.

 

I get it.

If I put my multimeter from battery ground to + on trailing coil I see 12v. If I do the same for leading nada. Shouldn’t the orange power the + on the leading coil once key is turned on according to the picture I posted in the original post…?

 

The orange wire is an input for the MSD.

For an MSD 6A on a Mazda 12A rotary, the orange wire is typically the positive (+) trigger input from your points or electronic pickup, and it usually connects to a switched 12V source or the coil's positive post (with a ballast resistor if using points) for power, but its function is signal-based; if it's the pickup wire (purple/green), you test the pickup's resistance (around 400-1300 Ohms), not a specific voltage value on the orange wire itself, as it's a low-current signal wire for triggering.

 

😂