pull the trouble codes. do you have a haynes manual?
turn the key from 'off' to 'on' three times in a row. do not turn jeep on. cyle it on, then off, on then off, on then off. on the third time, keep it 'on' in the odometer display the computer will flash you numbers, something like P0135 or similar. these are trouble codes. record all these 'trouble' codes, and hit the net. or post them up. someone will tell you what they mean.