OBD2 connection protocols

- There are 5 main communication protocols and each manufacturer usually uses always the same. In some cases, after the CAN-BUS implementation in 2008, some manufacturer continue supportting previous protocols.

• J1850 PWM (Pulse Width Modulation) Used by Ford Motor Company and Mazda.
• J1850 VPW (Variable Width Modulation) Used by General Motors and in some trucks or light trucks.
• ISO 9141-2 = Chrysler's earlier protocol, as well as European and Asian vehicles between 2000-2004.
• ISO 14230-4 KWP2000 (Keyword Protocol 2000) common protocol among manufacturers after the 2003.
• ISO 15765-4 CAN-BUS = Introduced in 2003, being commonly used for all vehicles after 2008.

- There are 2 variants of the KWP2000:

• ISO 14230-4 KWP SLOW (5 baud init, 10.4 kbaud)
• ISO 14230-4 KWP FAST (fast init, 10.4 kbaud)

- There are 4 variants of CAN-BUS they differ only in identifier length and bus speed:

• ISO 15765-4 CAN (11 bit ID,500 Kbaud)
• ISO 15765-4 CAN (29 bit ID,500 Kbaud)
• ISO 15765-4 CAN (11 bit ID,250 Kbaud)
• ISO 15765-4 CAN (29 bit ID,250 Kbaud)