GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2004 🢒 Regal 🢒 HVAC 🢒 HVAC Systems - Automatic 🢒 OnStar Schematics
Figure 1:

Power, Grounds, DLC, and Antennas
Object Number: 1223976 Size: FS
Master Electrical Component List
OnStar Description and Operation
Inputs and Outputs
Fuse Block - Underhood BAT 3 Fuse, Fuse Block - I/P ONSTAR, HTD SEAT Fuses, R/DEFOG and PWR/SEAT Circuit Breakers
Data Link Connector (DLC) Schematics
G203, Page 1 of 2
G203, Page 2 of 2
Figure 2:

Inputs and Outputs
Object Number: 1223986 Size: FS
Master Electrical Component List
OnStar Description and Operation
Power, Ground, DLC, and Antenna
Cellular Communication Schematic Icons
Cellular Communication Schematic Icons
Mirror, Dome, and Courtesy/Reading Lamps
Inside Rearview Mirror Schematics
G402, Page 1 of 2