Tach to Pcm

[davepl]

So a pull-up resistor is just the positive side of a pulsed ground system for when it doesn't have ground potential? And the ECM value for Tach Output is 12/resolution value?

Seems shorter when I say it ;-)

Thanks though, your explanation did clarify things! Still wondering what'll happen if I hook a logic probe up to a floating circuit (seriously!).