OBD2 system
Posted: Thu Nov 19, 2009 1:59 pm
Does anyone know what the OBD2 systems runs, ie. ISO, canbus, etc ?
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Taken from here: http://www.andywhittaker.com/ECU/OBDIIS ... fault.aspxWhenever 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.