Check the engine computer to see what codes are being stored. You can do this by turning the ignition on (don't start the motor, just turn the key to the on position), then off, then on again, then off, finally on a third time. After a few seconds the check engine light will flash the codes at you. Simple count how many times it flashes. The sequence will always begin and end with a 5. After the sequence is complete there will be a longer pause and then it will repeat. Here is what the sequence would be if you had codes 32 and 54 stored in the computer:
Write down the codes and check to see what they mean in a Haynes or Chilton manual.
1993 ZJ Limited 5.2 - no mods - Red with Gold (what were they thinking) trim.