Interesting issue, When tach is hooked up car won't turn off Options

[oildrips]

Lots of progress today/tonight. All vacuum lines rerun, dwell/timing set, new oilnpressure switch, oil changed, and I've isolated the issue where the car won't turn off when the key is removed, but there's some funky stuff happening.

So, before I started working on stuff, the car would start, and the engine would continue to run without the key. You'd have to stall it to shut it off. Once off, it would maintain power to the gauges (the generator light stayed lit), so you'd have to undo the battery. to reset everything.

I traced everything back to the tach. Without the tach signal wire hooked up, the key works fine. Engine starts/stops with the key.

Now, after doing all the work. I started the car, and decided to try the tach. Hooked it up, and sure enough the key didn't work to shut it off. I pulled the positive cable off the battery, and the car kept running on its own. I had to pull the coil leads to kill the engine.

Thoughts?

[oildrips]

Ok. So I encountered the same issue today. It's not the tach. And I pulled the switched wire from the coil, and it's still running. I believe I know what the issues is 100%, but need to have a question answered. In the engine bay, aside from the switched coil wire, is there another switched source? Possibly on the relay panel? The PO wired the relay panel (the plug on the driver's side rear corner that has 4 terminals on it) to the coil (it's spliced coil power/cold start valve). So I believe that they intended to use the coil wire (switched with the key) to trigger the relay board.

Sound feasible?

Sound legit?