- Description of On-Board Diagnostics

Data Link Connectors (DLC):

Scan Tool:
The underdash Data Link Connector (DLC) allows access to a variety of computer sensor circuit information, using several types of aftermarket scanners. Understanding the function of the circuit can be useful in obtaining information that might otherwise prove time consuming or impossible to obtain using other test procedures. Refer to manufacturers instructions for diagnostic test and code extraction.

Grounding Diagnostic Connector:
Ground the diagnostic test terminal with the engine not running and the ignition switch in the "ON" position. The "SERVICE ENGINE SOON" light will flash a Code 12 three times, and each code stored in memory three times. Once all Codes are retrieved, a Code 12 will follow. New codes cannot be stored in the PCM once the diagnostics mode is activated. See Diagnostic System Check under Computers and Control Systems/Testing and Inspection/Procedures for a complete system check. Testing and Inspection