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

Power, Ground, and DLC


Object Number: 1775094  Size: FS
Master Electrical Component List
Radio/Audio System Description and Operation
Body Control Module Programming and Setup
Speakers
B+ Bus - Underhood Fuse Block
Digital Radio
Data Communication Schematics
OnStar Schematics
G300, G301, and G302
Figure 2:

Speakers


Object Number: 1775104  Size: FS
Master Electrical Component List
Radio/Audio System Description and Operation
Body Control Module Programming and Setup
Digital Radio
Power, Ground, and DLC
Entertainment Schematic Icons
Entertainment Schematic Icons
Entertainment Schematic Icons
Entertainment Schematic Icons
Entertainment Schematic Icons
Entertainment Schematic Icons
Entertainment Schematic Icons
Entertainment Schematic Icons
Figure 3:

Digital Radio - U2K


Object Number: 1775110  Size: FS
Master Electrical Component List
Radio/Audio System Description and Operation
Body Control Module Programming and Setup
Speakers
Power, Ground, and DLC
Data Communication Schematics
Entertainment Schematic Icons
G300, G301, and G302