OBD2 Port

📖 YOUCANIC Automotive Glossary

OBD2 Connector Pin Assignment

The OBD2 connector (DLC) is a standardized 16-pin trapezoidal connector defined by SAE J1962, and each pin has a specific assigned function that determines how your scanner communicates with the vehicle and receives power. The most important pins to know are: Pin 16 (battery positive, always powered even with ignition off — this powers your scanner), Pin 4 (chassis ground), Pin 5 (signal ground), Pins 6 and 14 (CAN High and CAN Low — used on all 2008+ vehicles and many 2004+ vehicles), Pin 2 (SAE J1850 Bus Positive, used by Ford PWM and GM VPW protocols on older vehicles), Pin 7 (ISO 9141/14230 K-Line, used by older Asian and European vehicles), Pin 10 (SAE J1850 Bus Negative, used specifically by Ford PWM protocol), and Pin 15 (ISO 9141/14230 L-Line, used for initialization on some older European vehicles). Pins 1, 3, 8, 9, 11, 12, 13 are typically either unused or assigned to manufacturer-specific functions.

Understanding pin assignments helps DIYers troubleshoot scanner communication problems and diagnose CAN Bus faults directly at the DLC. If your scanner won’t connect or power up, you can use a multimeter to quickly verify the essentials: check for 12V+ between pin 16 and pin 4 (battery power and ground — if missing, check the OBD2 fuse), check for continuity between pin 4 and a known chassis ground point (if open, you have a ground problem), and on CAN-equipped vehicles, measure resistance between pins 6 and 14 with the ignition off (should read approximately 60 ohms from the two 120-ohm termination resistors in parallel — readings of 120 ohms, 0 ohms, or open circuit indicate CAN Bus problems). Some vehicles use additional DLC pins for manufacturer-specific communications — for example, some older Mercedes vehicles use pin 8 for a proprietary diagnostic protocol, and some GM trucks use pins for class 2 serial data. If you’re using aftermarket OBD2 adapters or splitters, verify they don’t short or bridge pins that shouldn’t be connected, as this can cause communication errors or even damage control modules. Keep the OBD2 port clean and free of debris — compressed air can remove dust, and electrical contact cleaner on a small brush can clean corroded pins.