If you have a autozone near you might wana have them hook it up to the computer and see if they can find the issue. Worth a check its free.
~Lev
Kinda hard to do if you can't start the jeep to drive it out there lol...
Here is how to get the code as far as I know:
The method you use to view the engine diagnostics is now different. Starting in 1998, the method of repeatedly switching on/off of the ignition is now used for programming the new Chrysler Sentry Key system. The Sentry Key was introduced in 1998 as an optional feature and by 2000 was standard on all TJs. Some 1998 models without the Sentry Key system may still use the older procedure. The way to tell if your Jeep has the Sentry Key system is if the plastic head on your keys are gray--you do. Black headed keys mean you don't have the Sentry Key system.
So on TJs with the newer diagnostic system, to see the codes you put the key into the ignition, push and hold down the odometer reset button, turn the key to RUN, then release the odometer reset button. When you do this you are rewarded with dancing number displays, the firmware version number, any error codes, then a diagnostic test of all the dash indicators and gauges. The gauges will, one by one, go through a calibration--the needles moving and stopping at major increments so you can check their alignment with the dial markings.
Output from the newer onboard diagnostics is easier to read now, as you get full 4-digits codes for much greater detail.