OBD-II Connector Pinout: The 16 Pins Explained

The connector

Every 1996-and-newer car sold in the United States has the same 16-pin diagnostic socket, the DLC. It sits under the dash on the driver side, within reach of the steering wheel. The shape is standardized, so any OBD-II scanner plugs into any brand.

The 16 pins

• 1 - manufacturer specific
• 2 - J1850 Bus+ (older Ford and some others)
• 3 - manufacturer specific
• 4 - chassis ground
• 5 - signal ground
• 6 - CAN high (the common pair on 2008 and newer)
• 7 - K-line, ISO 9141 and KWP2000 (older Asian and European cars)
• 8 - manufacturer specific
• 9 - manufacturer specific
• 10 - J1850 Bus- (older Ford and some others)
• 11 - manufacturer specific
• 12 - manufacturer specific
• 13 - manufacturer specific
• 14 - CAN low (pairs with pin 6)
• 15 - L-line, ISO 9141
• 16 - battery positive, live at all times

The manufacturer specific pins are the reason a code reader that works on one brand will not talk to another. They also carry some of the older manufacturer protocols.

Scanner will not power on

Check pin 16 for battery voltage and pins 4 and 5 for ground. The socket usually shares a fuse with the cigarette lighter, so a dead lighter often means a dead socket. Fix the fuse and the scanner wakes up.

Scanner powers but will not connect

Power is there, so the fault is on the data pins or in the protocol. A tool set to the wrong protocol reads nothing even though the car is fine. On older cars try pins 2 and 10, then 7 and 15, then 6 and 14. A bent or pushed pin in the socket is common on cars where a tool gets left plugged in.

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