DLC (Data Link Connector)
The standardized 16-pin connector plug, usually located under the dashboard, used to connect diagnostic scan tools.
The Data Link Connector (DLC) is the standardized 16-pin connector plug found in passenger vehicles, used to interface diagnostic scan tools with the vehicle's on-board diagnostic (OBD-II) networks and electronic control units. In most vehicles, the DLC is located under the driver-side dashboard, within easy reach of the steering column.
Through the DLC, technicians can read diagnostic trouble codes (DTCs), monitor live sensor data streams, run actuator tests, and reprogram or flash control modules. The connector pins are mapped to standard power, ground, and communication protocols (such as CAN Bus). If the DLC lacks power or has a broken pin, scan tools will fail to communicate with the vehicle's computer network.
Symptoms of DLC issues include a scan tool failing to power on when plugged in or displaying a "no communication" error. Diagnostics involve using a digital multimeter to check for 12 volts at pin 16 and chassis ground at pins 4 and 5. Common causes of a dead DLC are a blown fuse (which often shares a circuit with the cigarette lighter socket) or a damaged wiring harness behind the dashboard.