1995 Chevy Corsica no start

Car was towed over to my shop from another shop for a no start first I checked for codes I can not get any data out of computer I have tried 2 scanners just in case one was not working no luck checked all computer grounds and wiring every thing checks out owner got me another computer did not change anything used same prom went to chevy garage they told me that the prom should not stop me from getting data from the computer I think that there full of it I use alldata flow chart if all wiring and grounds are good it's either a computer or a prom tried the computer so that leaves the prom.I have spark 5 volt ref fuel press is 41 psi.I know when I did my voltage pin out on the computer the ckp sensor batt feed shows 12.3 volts they say with key on eng off it should be 0 volts thats the same for the 7x ref signal it shows 11.7 volts and it should be 0 volts. Rrunning out of things to check if you can tell me anything better to do let me know I think the prom is giving me the problem but at 100 dollars and you can't return it see what else it could be.