Diagnostic Circuit Check - Without Diagnostic Scan Tool

Data Link Connector:

OPERATION
The Computerized Engine Controls (CEC) System can be checked without a scan tool by grounding terminal "B" of the Data Link Connector with the engine not running and the ignition switch in the "ON" position. In this mode the Control Module will:

- Display a DTC 12 by flashing the Malfunction Indicator Lamp (MIL) "SERVICE ENGINE SOON". This indicates the system is operating properly.

- Display any DTC(s) by flashing the Malfunction Indicator Lamp (MIL) "SERVICE ENGINE SOON". Each DTC will be flashed three times then DTC 12 will be flashed again. New codes cannot be stored in the Control Module once the diagnostics mode is activated.

- Energize all Control Module cotrolled relays and solenoids except the fuel pump relay. This allows checking circuits which may be difficult to energize without driving the vehicle and being under particular operating conditions.

- The IAC valve moves to its fully extended position, on most models blocking the idle air passage. This is useful in checking the minimum idle speed.