Tach adapter- need to reduce pulses seen by car computer

Projects General Guidance
1

I am trying to adapt one brand engine (Chevy) to another vehicle (Dodge). I've worked most of the electronics out, but one I can't figure out is the tachometer circuit.

The Dodge computer uses a bus circuit to power the gauges, and this takes several inputs. For the tach, it uses a three wire 5V hall effect crank sensor that reads 8 pulses per engine revolution (PPR). The Chevy also uses a three wire hall sensor, but it inputs 12V and outputs 24 PPR. The sensor wiring for both involve +DC power supply, sensor ground, and output. I cannot add a second wheel and sensor to the engine, so I have to use the Chevy crank sensor for both computers.

Since this is a 3:1 ratio, is there a way the Arduino can be used to filter out or otherwise convert 2/3 of the pulses so the Dodge tach only sees 8 PPR?

Another option I have is to use the tachometer output (square wave) wire from the Chevy computer. The normal output is 2 PPR. I have some software that allows me to vary the output, so presuming I can adjust this to 8 PPR, this seems like an easier way to achieve my goal.

Thanks for any guidance here.

EDIT
I think I have solved this via the other software.

2

You don’t need an Arduino to do that, just a simple binary counter and a logic gate. Make a divide by three circuit. Or a divide by as many as you want. You simply pick up the presence of the binary count you want with logic gates and then use that to reset the counter.