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

OnStar System


Object Number: 780690  Size: LF
(1)Roof Harness
(2)Onstar Keypad
(3)Inside Rearview Mirror
(4)Cellular Telephone Antenna
(5)C393
(6)Global Positioning Satellite (GPS) Antenna
(7)Vehicle Interface Unit (VIU) and Vehicle Communications Unit (VCU)
(8)OnStar Jumper
(9)C391
Figure 2:

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 3:

Left Side of Rear Compartment


Object Number: 752817  Size: LF
(1)Speaker - LR, Connector
(2)Speaker - LR Subwoofer, Connector
(3)Evaporative Emission (EVAP) Canister Vent Solenoid, Connector
(4)P425
(5)C423
(6)Cellular Telephone Antenna Coaxial Cable Connector
(7)Global Positioning Satellite (GPS) Antenna Coaxial Cable Connector