92 Firebird V6 RPM Gauge Signal
 

Hey folks.

I got a spare Dash-Cluster for a 92' V6 Firebird and I
want to play around with it a little bit.

I want to build something like a "Dash-Simulator".

Most things are working but I need help with the Tachometer.
C'ant figure out which kind of signal goes to the Dash-Cluster
to the control the RPM-Gauge.

Speed-Gauge is working fine with a +12V-GND 4000ppm Square-Wave Signal.

After a lot of reading, I found out, that my V6-Tacho seems to need 3 Pulses per Revolution. So 60Hz Signal for 54Mph should do 1200RPM
on Tacho.

But same signal which is working for Speedo, does not do anything on Tacho.

So my question: what is Tacho really expecting?

After reading more and more, I think a sine-wave is required but not sure about that.
Not event sure if sqaure-wave on speedo is correct but working
for some strange reason.

Thanks for your help in advance.

Best Regards,
Serjo :)