Hey, still trying to get my new car running, (91 Z), I had to replace the steering column and afterwards the car wouldnt start, is this because the computer has to be reprogrammed to match the key or is there another option, if so how much does this usually cost? Thanks alot for the help.

 

The ECM itself doesn't know which key is being used. The vats is a separate unit that decides whether the right key is used, if it sees the proper resistance from the key it signals the ecm.
If you want to keep the VATS enabled you can take your old key and new key to a locksmith who will test the old key and will then cut a key with the proper resistor should cost about $10. The other options are to get a chip with vats disabled or to bypass the vats manually. To bypass it manually you have to check the resistance of the little chip. Once you know the resistance get a resistor from radio shack that is as close as possible. Then under dash there are two wires in an orange case that come from the lock cylinder in the column, you should have seen them when you pulled the old column, disconnect the harness and put the resistor inline bypassing the ignition cylinder. Hope this helps.