Sounds like readiness flags got you.

Basically, there are several batteries of tests that have to run (and pass) to set each flag. These are also the tests that determine whether or not the SES light comes on.

The only way to run the tests is to drive the car. They run automatically, in the background as you drive.

Since it's a GM car, I have some relevant experience relating to getting those flags to set. Let me know if you need help.

1990 Montero RS (In pieces... for now)

KG6VNX