Many vehicles separate the bus on which the OBD resides from the one that actually controls anything. Here's how Chrysler handles it (and by extension, most mo

Many vehicles separate the bus on which the OBD resides from the one that actually controls anything. Here's how Chrysler handles it (and by extension, most modern Jeeps): http://tucrrc.utulsa.edu/DodgeRam_files/NetworkTopology.jpg http://tucrrc.utulsa.edu/DodgeRam_files/NetworkTopology.jpg