Without Scan Tool

Data Link Connectors (DLC):

The [1][2]DLC is located in the passenger compartment. Terminal B of the connector is the test terminal and terminal A is the ground used for diagnostic display.

NOTE: If the Data Link Connector is the 16 PIN type, a scan tool must be used to display diagnostic trouble codes. See procedures for use with a diagnostic scan tool. With Manufacturer's Scan Tool

If the test terminal is grounded with the ignition on and engine not running, the system will enter the diagnostic mode. In this mode, the computer will display a Code 12, followed by any stored diagnostic trouble codes. In the diagnostic mode, the computer will also energize all computer controlled relays and solenoids.


SYSTEM CHECK:
The system check is performed through the twelve pin data link connector (DLC) under the instrument panel in the passenger compartment.

1. 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. Chart A-1 No Malfunction Indicator Lamp (MIL)

2. Ground the diagnostic test terminal (connect [1][2]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.


NOTE: If the MIL lamp does not display code 12, or comes "ON" and stays "ON", then refer to "DIAGNOSTIC CHARTS/A-CHARTS" and see "Chart A-1, No Malfunction Indicator Lamp", &/or "Chart A-2, Malfunction Indicator Lamp "ON" Steady". Related Tests, Information and Procedures


3. Diagnostic Trouble Codes (DTC) - Proceed to the applicable code chart if a DTC is displayed. Testing and Inspection

NOTE: Some diagnostic charts may require the use of a "Scan" tool.

If all systems appear to be functioning, but problem still exists, see DIAGNOSIS BY SYMPTOM. Testing and Inspection


FIELD SERVICE MODE:
If the test terminal is grounded with the engine running, the system will enter the field service mode. In this mode, the "CHECK ENGINE" or "SERVICE ENGINE SOON" light will indicate whether the system is in open or closed loop operation. If the system is in open loop operation, the light will flash rapidly (approximately two and one-half times per second.) Closed loop operation is indicated by the light flashing slowly (approximately once per second.)