OBD2 Protocols. What are their difference?

Is there a practical need for the driver to understand what OBD2 protocols exist and what is their significant difference? Not exactly. Modern diagnostic devices, give only important information. Specifically, the application supports full inCarDoc OBD2 Protocols. However, it is desirable to know, why there are several types of protocols, and what are their key features. 

With the help of OBD system users get access to key components of the vehicle. You know well, a diagnostic for trouble codes help to identify the car unit's malfunction. Drivers should rise technical awareness of the car before its terrible breakage. As a result, protocols appeared as the requirements to interchange digital information between ECU and OBD tool.  

The reason, why automobile may not be 100% compatible with OBD2, is Communication Protocol. However, this problem rarely concerns modern cars. Therefore, there are five the most spread protocols, which provide ECU and OBD tool communication.

SAE J1850 VPW. Attributes of the protocol include an open architecture, low cost, and 10.4 kbps signal rate. VPW or  Variable Pulse Width was developed by General Motors. This obd2 protocol is used by cars of GM group, for instance, Ford. Signals are transmitted via 2-nd pin.

SAE J1850 PWM. PWM is high-speed (of 41.6 Kbytes/s) Pulse Width Modulation. It is used in Ford, Jaguar and Mazda cars. Signals are transmitted via two wires connected to pin 2 and pin 10 of the diagnostic connector.

ISO 9141-2. The Protocol is extended to Chrysler, cars of Asian and European production. This Protocol has a data transfer rate slightly lower than VPW. The protocol ISO 9141-2: has similar features with ISO 14230. Interesting to note, that the Scann-tool based on ISO 9141 also works with protocol ISO 14230, BUT not vice verse.  To facilitate inspection of the car the scan-tool send a special 8-bit code to the ECU via K-and L-lines. This process repeats for several times.

ISO 14230 KWP2000.  This protocol is found in Asian vehicles. Has the same principle of work as previous protocol. The data transfer rate from 1.2 to 10 Kbytes/s in the fast version.

ISO 15765-4/SAE J2480 (CAN). You’ll find this protocol in many new cars (cars made from 2008) as it was invented for cars that didn’t subject to obd2 standards by law. 

The CAN Protocol was developed by Bosch for automotive and industrial applications. As part of the OBD2 standard, the Protocol uses 2 contacts to exchange a signal: 6 and 14. It is the fastest and most perfect. Using a separate microcontroller and embedded transmission speed is adjustable from 20 Kbps to 1 Mbps.

InCarDoc application and branded Adapter has next capabilities: 

• Read & Clear diagnostic trouble codes
• Support Full OBDII protocols 
• Support iOS & Android devices 
• Smart parameters scanning in real-time (Engine RPM, Calculated Load Value, Coolant Temperature) 
• Reliable and stably working adapter
• Wide range cars compatibility  

If Check Engine lights, use inCarDoc to check the Engine!