what scanning tool do I need to do an electronic diagnostic?
1990 lumina 3.1l

Obd1

to pull codes, all you need is a paperclip jumped across the a-b terminals on the diagnostic link with the key on/engine off and watch the check engine light counting the flashes. IF you're looking for real-time sensor output with the car running, you need a relatively expensive scan tool made by Snap-on, Actron, etc...