Ok, to answer my own question and if anyone else wanted to have more of an understanding... here is this:
ECSD - Injection Pressure Regulator (IPR) - 1994-1997 Power Stroke FAQ
From this site even. This shows all the sensors (inputs) and outputs to and from the PCM on a 94-97 Powerstroke Diesel.
I'm guessing if any of these aren't working or plugged in correctly the engine will either not run right or not run at all. Also, I'm guessing the PCM will know about it and tell us with a code. That I do not know for sure.
That's a VERY good link with good diagrams for those who didn't know about it.
Also, Diesel Care and Performance has a good link here:
Powerstroke
This has good explanations for these same things.
