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

Onstar Components


Object Number: 933276  Size: MF
(1)Radio
(2)Inside Rearview Mirror (ISRM) (w/ Onstar Switches)
(3)GPS Antenna
(4)Cellular Telephone Microphone
(5)Cellular Antenna
(6)C300 and C303
(7)Vehicle Communication Interface Module (VCIM)
(8)Hazard Switch, Dimmer Switch, Traction Control Switch Connectors
(9)GPS Antenna Coax Lead Connection
Figure 2:

Cellular/Navigation Antenna


Object Number: 1702882  Size: MF
(1)Cellular/Navigation Antenna