[Second Series]

I’ll have to convert the VSS to something the Arduino can detect, Multiply that to get the 128,000ppm and use some external circuit to get this kind of waveform, the 4000ppm and 2000ppm can be produced with code and boosted to 12v with discrete components. I could add a potentiometer to adjust the multiplier for the 128,000 signal to accommodate a range or gear ratios and tire sizes.

I’ll need to take some more o-scope readings to double check the math, let’s look at it from the other end.
Stock tire size is 225/75R16, or 29.3” so 3.14 x 29.3 = 92.002” circumference of tire. 63,630 inches in a mile. 63,630/92.002 = 691.615 tire rotation per mile x 3.73 gear ratio = 2,579.725 driveshaft revs per mile. 2,579.725 x 40 teeth = 103,189.018 pulses per mile. At 60mph(1 mile a minute), that’s 103,189 ppminute And 103,189/60s = 1,719.81667pps, or 1,719.81667Hz @ 60MPH
At 20mph take 60minutes/20mph = 3, the vehicle travels 1 mile in 3 minutes. At 103,189 ppm/3minutes = 34,396.333ppminute. 34,396.333ppminute/60seconds=573.27Hz So at 20mph, the vehicle travels .333 miles in 1 minute with 573.27Hz from the VSS.
Take this equation, plug it into a spreadsheet, and come up with a chart for MPH vs. VSS frequency: