service engine light comes on

Pull the code(s) and see what comes up. On that one it is easy to do, you only need a jumper wire and read the flashes from the light.

https://www.2carpros.com/articles/buick-cadillac-chevy-gmc-oldsmobile-pontiac-gm-1983-1995-obd1-code-definitions-and-retrieval-method

https://www.youtube.com/watch?v=UIKdbTFvyUU