This document will help interconnect any devices to vehicle CAN-bus on application level. Now you can read all vehicle messages in SAE standard and get the explanation of them based on this document.

SAE+J1939-01-2000.pdf SAE+J1939-11-1999.pdf SAE+J1939-13-2004.pdf SAE+J1939-15-2003.pdf SAE+J1939-2005.pdf SAE+J1939-21-2001.pdf SAE+J1939-31-2004.pdf SAE+J1939-71-2006.pdf SAE+J1939-73-2004.pdf SAE+J1939-74-2004.pdf SAE+J1939-75-2002.pdf