What type of signal for tacho.
 

I am starting to build a shift light for my hillclimb/sprint RA, I have identified the wires which feed the tacho but before I pull the dash apart for a test does anyone know if they are a pulsed input or a variable voltage input.

Thanks in advance.

PWM i believe. Try http://www.ravensblade-impreza.com/, that will have the pinouts and some useful info for you

It is a battery voltage square wave (not PWM) with pulses every half engine revolution on my MY00.

Tacho signal
 

John therefore will a voltmeter read the signal if not what will I need to read it.

Yes, a DVM such as my cheapo from Maplin will read it in frequency mode.

Thanks a million, just the info I need to keep me busy over Christmas