Most users of an auto diagnostic scan tool may ask yourself “What OBD Protocol is my car?” There 5 different OBD II protocol in use. Generally, GM cars and light trucks use SAE J1850 VPW. Chrysler, European and Asian vehicles use ISO9141-2 or KWP2000 (ISO 14230). Ford uses SAE J1850 PWM. All vehicles sold in the United States in model year 2008 and later use CAN bus (ISO 15765-4). Please note that there are always exceptions to these general rules.

There is a method of knowing what protocol a vehicle use by examining layout of DLC. The presence of a metal contact in specific pin determine which one it is.

  • Pin 2 & 10 are used for J1850 PWM and J1850 VPW
  • Pin 7 is used for ISO 9141-2 and KWP2000
  • Pin 6 & 14 are used for CAN bus

DLC Pin Layout

  • Pin 7 is also known as K-Line
  • Pin 15 is also known as L-Line
  • Pin 16 have battery voltage
  • Pin 4 is chassis ground
  • Pin 5 is signal ground

OBD II Protocols

  • SAE – Society of Automotive Engineers
  • PWM – Pulse Width Modulation
  • VPW – Variable Pulse Width Modulation
  • ISO – International Organization for Standardization
  • KWP – Keyword Protocol
  • CAN – Controller Area Network
  • DLC – Data Link Connector, aka OBD port, OBD connector, J1962

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