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
- 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
- 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