On a '96 LT-1 Camaro, does anyone know if the VSS signal going into the PCM is the same identical signal that is output by the PCM (to the speedo and cruise control). In other words, if the VSS signal were to be connected directly to the speedometer, would the speedometer work and read accurately??? Thanks for the help.

 

The PCM out signal will not be the same as the VSS out signal. The PCM has to convert the VSS signal to speed, based on the programmed values for tire diameter and rear axle ratio.

You might want to look at something like the Dakotal Digital speedo interface box. It allows you to alter the VSS signal (ratio) by using various combinations of DIP switches.

 

Thanks Fred, I think the Dakota interface is what I am looking for as I as eliminating the factory PCM and still need to drive the speedo (the aftermarket PCM won't do it).

 

Why not keep your PCM to run the speedo. That's what I did. The engine runs on a MoTeC M48Pro, but the stock PCM was kept to run the speedo and the IAC motor (M48Pro could only run a PWM IAC, not a stepper motor), and actually managed to keep the emissions functioning.

 

With an OBDII original car you can run the VSS/speedo off the ABS system with a little work, that is if you still have your ABS system in the car....ie the brain is still plugged in and a wheel sensor is working.