On the ALDL connector below the radio... jump the 2 terminals with a wire (paper clip) that are on top right row on the connector. The check engine light will flash out the code(s), take notice of how fast they flash. For example: code 12 will read.......Blink(1)............................Blink...Blink(2) and will repeat itself. If you jump the terminals right the fan should come on :wink:. Also if the code is "system rich" it could be the o2 sensor or it could be something that is giving the ecu bad info and dumping fuel into it. Also, get a scantool!!!