To all the electric gurus, I need a pulsed negative for my Speedhut tach. Can I tap the #4 pin at the ECU to achieve what I need? Is this a reasonable solution? Suggestions?

I have the FSM and a color schematic of the electrical system but reading an electrical diagram is not my strong suit. Well, ok, I'm a wiring theory moron but more than capable of soldering and heat shrinking.

Thanks!

'78 280z

The stock tach uses the blue wire from coil negative. Won't that one work? Not sure what you mean by "pulsed negative". Why do you think that pin 4 would work?

Pin 1 is the signal from the negative side of the coil.