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

Data Communications


Object Number: 1911923  Size: FS
Master Electrical Component List
Data Link Communications Description and Operation
Control Module References
High Speed GMLAN
Figure 2:

High Speed GMLAN


Object Number: 1926652  Size: FS
Master Electrical Component List
Data Link Communications Description and Operation
Control Module References
Data Communications