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

Power and Ground


Object Number: 661065  Size: FS
Master Electrical Component List
OnStar Description and Operation
Keypad and Mic Signals
Rear Fuse Block- RDO and CD/PH Fuses
Rear Fuse Block- RDO and CD/PH Fuses
Class 2 Serial Data Line
G202 (1 of 4)
G202 (3 of 4)
Figure 2:

Keypad and Mic Signals


Object Number: 661071  Size: FS
Master Electrical Component List
OnStar Description and Operation
VIU Output Signals
Power and Ground
G400 (1 of 2)
Figure 3:

VIU Output Signals


Object Number: 661072  Size: FS
Master Electrical Component List
OnStar Description and Operation
VIU and VCU Signals
Keypad and Mic Signals
Horns Schematics
Power, Ground and Serial Data Lines
Figure 4:

VIU and VCU Signals


Object Number: 661067  Size: FS
Master Electrical Component List
OnStar Description and Operation
VIU Output Signals