YOU SAID it's a 90's jeep right?
if so, try this.
without starting the car........cycle the key from off to run 3 times...leave it in run the third time. now, count the flashes of the check engine light. there'll be long flashes, and short flashes. the long ones are the "10" and the short are the "1".
so, 3 long, followed by 2 short, would be code 32. if there's more than one code, they'll be seperated by an approx. 2 second space.
you more than likely will see a code 55 and a code 12. the sequence is ended when you see 55 for the 2nd time.
let me know what the codes(if any) are, and i'll look em up for ya.
john