The data link connector (DLC) provides the technician a means of accessing serial data for aid in diagnosis. This connector allows the technician to use a scan tool in order to monitor the various serial data parameters, and to display diagnostic trouble code (DTC) information. The DTC(s) stored in the ECM memory can be retrieved through a hand-held diagnostic scanner plugged into the DLC, or through a PC based software program that is designed to interface with the ECM.