Unfortunately you are stuck in the ODB 1.5 debacle. Very few scanners actually read these as it's a mixture of ODB1 codes and some ODB2. You can read a little about it on Wikipedia:
http://en.wikipedia.org/wiki/On-boar...ostics#OBD-1.5
I have a 95 Corsica that I've never been able to read the codes for. I've heard GM Tech 1 will read it, but I've taken it to a few dealers that couldn't do it.