OBD2 system

[neilGTI]

Does anyone know what the OBD2 systems runs, ie. ISO, canbus, etc ?

[alexperkins]

its not canbus. Its K-Line

[tegwin]

It is an OBD2 ISO K-line

Whenever I read specifications, I wonder what the people were smoking when they were writing them. A typical example is the naming of the ISO part of the OBD-II interface; the K and L lines.

Well, the line that you use to communicate with the ECU is the K line. Most newer ECUs allow you to wake-up the ECU with this line too (i.e. the 5 baud, 0x33 transmission).

Older ECUs need to be woken-up by transmitting 0x33 at 5 baud on the L line. To the best of my knowledge, the L line is then redundant and not used.

So, that's it. K line is the ISO data to and from the ECU and the L line is sometimes needed to wake-up the ECU.

Taken from here: http://www.andywhittaker.com/ECU/OBDIIS ... fault.aspx