I have a 91 Corsica.
A few months ago my wife got into the car to go to work one morning and the car would not start. It turned over fine but would not go.
This past week I got around to try and fix it. It was not getting any fire on #2 cylinder so I changed the coil. It still would not start. So I took the ignition module off and had it tested, no good, so I replaced it. Still no start. Then I thought crank sensor, and replaced it. Still no start. All this time the computer is only coding 12, nothing else. Then I thought computer. So I took it off and took it over to a friend of mine's place (Rick) to see if I could match it up with one of the three computers that he had. No match.
Rick tells me in order to reset the computer you have to disconnect the battery and wait a few minutes, turn the key to the run position and hook the battery back up (with the key still in the run position). I put the computer back in and turned the key to run and hooked up the battery.
The car runs great.
After I changed the ignition module I had tried to reset the computer by disconnecting the battery for a few minutes but had never hear of leaving the key in the run position.
You learn something new everyday. I hope this helps someone.