DIY RPM tachometer

[Carrotzombie]

I just want to start off with I am not a car guy but, I am trying to learn a little bit just for a project I kinda want to do. I own a 93 Ford Ranger (v6 3.0L) and I would like to get/make a tachometer for it. Mainly because I haven't seen a small tach dial I like or that isn't too expensive.
My plan is to use a arduino or raspberry-pi, which would display to a small screen or incremental LED indicator. I'm trying to find out if i should pull the signal off of the ICM(tan-yellow stripe) or ECU(white-pink stripe)? From my knowledge the signal from the ECUs tach output should be a square wave that increases its frequency with rpm.

 

[RonD]

Welcome to TRS

white-pink stripe wire's signal comes from the TFI module(ICM) and goes TO the computer, but yes it is a digital pulse signal vs the analog Coil Driver wire(tan-yellow stripe) signal

You can also use any spark plug wires inductance to generate the pulse you need, this would make it easier to move it to the next vehicle, assuming it wasn't a diesel engine