Ok, on an electronic speedo does the PROM include rear gear ratio information that will affect the speedometer?

For example, if you were to switch gear ratios and changed the speedo gears to match the new gears, would the speedo be accurate?

Or would it be off because the PCM still thinks the old gear ratio is still in??????

OR does the PCM/PROM play no part in the speedometer operation???

 

well the VSS is the ecm's way to see vehicle speed for a couple of functions TCC lockup, highway spark mode high way fuel mode and a couple other things like IAC offest per mph to help aviod stalls at sudden stops. so the VSS does play a part in ECM operations. however i dont think the VSS drives te speedometer in your application i could be wrong but i dont think so.