The button states could easily be read by using ... but came to the conclusion that it would be easier to direct wiring the Arduino outputs to the appropriate spot on the head unit’s circuit ...

After all, the Arduino isn’t actually measuring the CPU speed, nor is it directly controlling it (that’s still done by the original Turbo button wiring). But the truth is, even back in the day ...

This typically includes resistors, push buttons ... in the Arduino IDE. The most beginner-friendly sketch here is the "Blink," which simply makes an LED blink. You won't need to wire up anything ...