Depends if you have a 12 pin or 16 pin Data Control Link. If it's 16 pin, then you have to use a scan tool.
If it is 12 pin, then you use pins A and B:
As you look at the connector, the top row, all the way to the right is the A pin, and right next to it, on its left, is the B.
F E BLANK BLANK B A on the top row.
Then you use this procedure:
The system check is performed through the twelve pin data link connector (DLC) under the instrument panel in the passenger compartment.
- With ignition "ON" and the engine not running, observe the Malfunction Indicator Lamp (MIL). The lamp should be"ON". This is a bulb check to verify the "SES" light is working, and that the computer can complete the circuit. If there is no "SERVICE ENGINE SOON" light, refer to DIAGNOSTIC CHARTS/A-CHARTS/CHART A-1, NO MALFUNCTION INDICATOR LAMP . See: Diagnostic Trouble Code Tests and Associated Procedures\Related Tests and Information\A Charts\Chart A-1 No Malfunction Indicator Lamp (MIL)
- Ground the diagnostic test terminal (connect DLC terminals "A" & "B") and observe the MIL lamp. When the diagnostic terminal is grounded with the ignition "ON" and the engine "OFF", the lamp will go "OFF" for a moment, then flash a code 12. Code 12 is displayed by the MIL lamp flashing once, followed by a short pause, then two flashes in rapid succession, then a longer pause, and the code will repeat two more times. This is a diagnostic mode check. Code 12 displays to indicate the computers diagnostic mode is working. After code 12 is displayed a total of three times, any stored diagnostic trouble codes will be displayed in in the same manner, in numerical order. Each code will display three times before the next stored code. After all diagnostic trouble codes are displayed, code 12 will display again, and repeat until diagnostic mode is exited by removing the jumper wire from the diagnostic connector.
If you don't get a code 12, then you have a problem in the data link harness itself perhaps and you'll need a repair shop to further diagnose.