GM Service Manual Online
For 1990-2009 cars only
Figure 1:

Class 2 Serial Data


Object Number: 1907098  Size: FS
Master Electrical Component List
Data Link Communications Description and Operation
Control Module References
High Speed GMLAN Serial Data
Figure 2:

High Speed GMLAN Serial Data


Object Number: 1907292  Size: FS
Master Electrical Component List
Data Link Communications Description and Operation
Control Module References
Class 2 Serial Data