How to read codes for infl rest light?

You can read the codes in flashes of the air bag light, but only the current code(s)
You ground the K terminal to the A terminal in the ALDL connector. Then turn on the key and count the flashes. It will start with a 12 then the code(s) that are stored. So if you see one flash then 2 flashes, the 3 flashes and 1 flash, that would be the 12 and a code 31 and then it will repeat until you remove the jumper. Then post them here and we can look them and relevant testing up.

Thank you. I am not getting the vehicle until next week. I will respond with more at that time. Thanks

If you want a lot more info than just the flash codes, see if you can find a Tech1 or Snap-On MT2500 with the GM cartridges. They didn't have as much info as modern OBD2 cars but there is quite a bit of information on the OBD1 GMs. Especially helpful on cars that have EFI and airbags as they can be a bear to test items when you are blind to what is actually happening.

The only code that flashed was 12. Reset light. On the test drive the lights were off. Thanks again.

Intermittent air bags lights are a bit of a worry. However, if it stays off then it should be okay.