The Data Link Connector (DLC) provides the means of accessing and retrieving data from the vehicleí»s on-board computer.

A Code Reader or Scan Tool is connected to the DLC to retrieve Diagnostic Trouble Codes (DTCs) and other enhanced data from the computer.

On OBD1 systems, the size, shape and location of the DLC varies between manufacturers. Typically, the DLC is located in the engine compartment, or under the left side of the dashboard.

OBD2 Systems use a standardized 16-pin DLC, as defined by SAE J1962/ISO 15031-3.

Several pins of the DLC are associated with specific features or functions used by OBD2-compliant control systems, and are required to be implemented uniformly by all vehicle manufacturers. These pins provide operating power (from the vehicleí»s battery) to the Code Reader or Scan Tool, and provide the data paths for the various OBD2 í░communication protocols.í▒ The functions of the remaining í░unassignedí▒ pins manufacturer-defined, and can be used for such features and functions as Anti-Lock Brake Systems (ABS), Supplemental Restraint Systems (SRS), etc.

The OBD2 DLC connector pin assignments are:

1 Unassigned 9 Unassigned
2 J1850 Bus+ ( 10 J1850 Bus-
3 Unassigned 11 Unassigned
4 Chassis Ground 12 Unassigned
5 Signal Ground 13 Unassigned
6 CAN High (J-2284) 14 CAN Low (J2284)
7 ISO 9141-2 (K Line) 15 ISO 9141-2 (L Line)
8 Unassigned 16 Battery Power

While the DLC location varies between vehicle makes and models, it is usually located under the instrument panel (dash), within 16 inches of the steering column, on the driverí»s side of most vehicles. It should be easily accessible from a kneeling position outside the vehicle with the door open.