More than just the CAN buss also. On the '04, there is the CAN, ISO, SCP and UBP busses. I don't know if all of those continued on through 05 and beyond, however. I believe the eventual goal of OBD-II was to be all CAN eventually.

Attached is a PDF with a description of the 4 busses and what they connect. This is for an 04, I can't vouch for any other years.