How do you reset the maintenance light on 1991 Jeep Wrangler 4.0L?

There's no maintenance light in the traditional sense on a 1991 Jeep Wrangler 4.0L. These Jeeps didn't have sophisticated onboard computers with maintenance reminder systems like many later vehicles. Instead, you relied on the owner's manual for recommended maintenance intervals (like oil changes, tune-ups, etc.).

If you're seeing a light that *looks* like a maintenance light, it's likely a different indicator light – such as the check engine light (often denoted by a stylized engine), which indicates a problem detected by the onboard diagnostic system (though this is quite basic on a '91 Wrangler). If it's the check engine light, you'll need to diagnose the underlying issue using a code reader.

In short: There's no maintenance light to reset. Consult your owner's manual for the recommended maintenance schedule and perform those tasks accordingly. If another light is illuminated, investigate *that* light's meaning.