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

Cell 154: Vehicle Interface Unit (VIU)


Object Number: 355210  Size: FS
Cellular Communication Components
OnStar Circuit Description
Cell 154: Vehicle Communication Unit (VCU) and Floor Handset
OBD II Symbol Description Notice
OBD II Symbol Description Notice
OBD II Symbol Description Notice
OBD II Symbol Description Notice
Radio/Audio System Schematics
Ground Distribution Schematics
Power Distribution Schematics
Figure 2:

Cell 154: Vehicle Communication Unit (VCU) and Floor Handset


Object Number: 355211  Size: FS
Cellular Communication Components
OnStar Circuit Description
Cell 154: Vehicle Interface Unit (VIU)