I don't know for sure on that model, but many times manufacturers put in something like that to let you know that a certain number of miles have gone by and that it is time to do something.

Found this with a quick google:

Long Answer: On the Wrangler the "Maintenance Required" light is triggered by a timer function and is not associated with a particular fault. Most people associate it with the scheduled replacement of the O2 sensor. The "Check Engine" light is the more serious and is associated with some sort of discrepancy. The "Check Engine" light can be reset by disconnecting the negative battery terminal but don't do so before retrieving the fault codes stored in the computer. You can find the procedures and diagnostic code meanings at http://minimopar.knizefamily.net/

 

91 should be fuel injected, computer. The carb engines had a gray box near the gas pedal. I know my 90 had one, I would think they did away with that on F.I models.

Look by your gas pedal for a clear grayish box and unplug it. It will have gears inside of it......

here you go, search works awesome
http://www.jeepforum.com/forum/showthread.php?t=253964&highlight=Maint+Required

the 2nd post, a link to what it looks like it.

 

wow, that made for some interesting reading, i would have searched but i've come to the conclusion we all like to share our knowledge on a more personal level.....lol......
so? will the scanner that they use to scan for you at advance auto reset it or will i have to buy one? i don't know anyone who has one handy.
thanks for the great links and info and quick responses,
dave

 

The maintenance req'd light cannot be reset. The timer must be replaced or the bulb pulled. Since I couldn't find the timer pictured in the linked post I ended up pulling the bulb.

 

wow, that made for some interesting reading, i would have searched but i've come to the conclusion we all like to share our knowledge on a more personal level.....lol......
so? will the scanner that they use to scan for you at advance auto reset it or will i have to buy one? i don't know anyone who has one handy.
thanks for the great links and info and quick responses,
dave

I didn't see a reset on mine. If it were mine I would just unplug it and the light will go out. I think those units are a one time deal but I'm not 100% sure. If it's a one shot deal I wouldn't waste money on it. I would however replace the o2 sensor, they do age and act up. The O2 is a key piece to F.I engines. --think gas milage

 

Up thru 1990 the Wranglers had a mechanical timer that controlled that light.
The timer is a plastic box attached to the firewall up and to the right of the gas pedal. This timer box is not resettable. It has to be replaced (or disconnected) to make the light go out. It was meant to be replaced when you replaced the O2 sensor.

In 1991 they eliminated the mechanical timer box and the light is now turned on & off by the ECU computer.