While a failing emissions system *could* lead to a failed inspection, the check engine light itself is just an indicator. The inspector will likely use an OBD-II scanner (your 1996 might not have full OBD-II, but a scan tool may still work) to read the trouble codes stored in the computer to determine the nature of the problem.
Location of the Check Engine Light:
On a 1996 Ford Explorer XLT, the check engine light is usually located on the instrument cluster, the panel with your speedometer, tachometer, fuel gauge, etc. It's typically an amber or yellow light and often depicts an engine outline. Look for a symbol like this: (A stylized engine shape).
In short: The inspection checks many things, and a malfunction indicated by the check engine light is *one* potential reason for failing, but the light itself is just a symptom, not the entire inspection process.
