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

OnStar System


Object Number: 676947  Size: LF
(1)Roof Accessory Jumper
(2)Cellular Telephone Microphone
(3)OnStar Button Assembly
(4)Cellular Telephone Antenna
(5)Global Positioning System (GPS) Antenna
(6)Vehicle Interface Unit (VIU) and Vehicle Communications Unit (VCU)
(7)OnStar Jumper
Figure 2:

Inside Rearview Mirror


Object Number: 695135  Size: MF
(1)C421
Figure 3:

Vehicle Interface Unit (VIU) and Vehicle Communications Unit (VCU)


Object Number: 695150  Size: MF
(1)OnStar Jumper
(2)Cellular Telephone Antenna Connection
(3)C423
Figure 4:

Rear Package Shelf-Left


Object Number: 695155  Size: MF
(1)Global Positioning System (GPS) Antenna Connection
(2)Cellular Telephone Antenna Jumper Connector
(3)Cellular Telephone Antenna Connector
(4)C423
(5)Body Harness