Data link connector (automotive)
The Data Link Connector (DLC) is the multi-pin diagnostic connection port for automobiles and trucks used to interface a scan tool with the control modules of a given vehicle and access On-Board Diagnostics and live data streams.
The OBD-II DLC (post-1996 vehicles) is usually located under the instrument panel on the driver side, though there are several exceptions. Prior to 1996, many DLC's were in the engine compartment, usually near the fuse block. Also, prior to 1996, there was no standardization for these connectors, and each manufacturer had its own shape with a unique pin arrangement. After 1996, many manufacturers retained their proprietary connectors in addition to the OBD-II interface, because OBD-II ports are only required to transmit emission-related codes and data.