1.) Locate the dignostic connection under the driver side dash; it's a black plastic box that could be on either side of the steering column
2.) Turn the ignition to the "on" position without the car running
3.) Unfold a paper clip and complete the circuit with the two ports that are next to each other (see photo)
4.) Once circuit is closed (paper clip is in both ports) you'll hear the radiator fans turn on and you will see the Service Engine Light begin to blink on the instrument panel; the SES light will blink once, pause, and then blink twice to start off. The number of blinks equals the number corresponding to the digit (example above in step 4 would be code #12, code #12 means ECM works properly)
5.) To determine fault code, let the computer cycle through code #12 three times; afterwards the blinks will be indicating current fault code in the system
6.) When all fault code are shown and continuously repeating, pull out paper clip to stop process; shut off ignition
7.) Check service maunal for what code number coressponds with faulty circuit / sensor
8.) To delete codes after repair work, pull negative battery cable for about 5 - 10 minutes