How to check Check engine light?

[AuroraGirl]

True.

I suspect that a '98 is new enough that a scan tool could command the instrument cluster to turn on/off the warning lights on command.

I would think yes, since its an Output of the PCM most likely.

 

[Schurkey]

Just as a check on my advice, I connected the scan tool to my '03 Trailblazer. Mostly I was looking at misfire counts--discovered that #5 coil took a dump a few days ago. Installed a new coil in my driveway today--warmest day in weeks. Working outside in 25F weather was not as bad as I was expecting--and the job went quickly.

Point is, when I commanded the instrument cluster to turn on all the lights, everything lit up except the light for cruise control (it's been burnt out for years--ever since about two days after I had the whole thing apart and replaced all the stepper motors) and the MIL. I was pretty sure the "Check Engine" "Service Engine Soon" light would turn on and off with the rest...but it doesn't.