GM Service Manual Online
For 1990-2009 cars only

The power is supplied from the radio/phone fuse in the rear compartment fuse block via CKT 40 (ORN) to the cellular telephone module connector at terminal A. The module is grounded at terminal B via CKT 1051 (BLK) to G400.

The cellular telephone module contains the following components:

    • The cellular telephone transceiver
    • The cellular telephone modem

The module controls the cellular telephone handset power via CKT 1941 (BRN) and regulated 8 V power CKT 1266 (RED). The module controls the handset display and receives the handset/keypad data on the following circuits:

    • CKT 679 (PPL)
    • CKT 1156 (PPL WHT)
    • CKT 1798 (GRY/BLK)

The power is supplied to the cellular telephone handset at terminal 5 from the radio/phone fuse in the rear compartment fuse block via CKT 40 (ORN). The handset is grounded at terminal 10 via CKT 1051 (BLK) to G400. The handset contains the following components:

    • The keypad
    • The display
    • The microphone
    • The ear speaker

The handset communicates shielded signals to the following components of the cellular telephone module:

    • The mouthpiece audio CKT 1153 (LT BLU)
    • The earpiece audio CKT 1154 (DK BLU)
    • The audio ground CKT 1235 (LT BLU/BLK)

When the handset is placed in the docking cup, the phone operates in the hands-free mode. This mode allows the roof-mounted microphone to receive the driver's voice. During the hands-free mode, the vehicle radio mutes and the incoming cellular telephone audio is routed through the radio's speakers. When the handset is removed from the cup, the hands-free feature is disabled and the radio is unmuted. The handset must be held to the driver's head for voice conversation.

The cellular telephone microphone is wired to the cellular telephone module via CKT 655 (GRY) and CKT 814 (NAT). During hands-free operation, the module provides mono audio output to the vehicle audio system on CKT 658 (DK BLU) and CKT 659 (BLU/BLK).

The module communicates on the class 2 serial data line CKT 1807 (PPL). The module uses the class 2 serial data line CKT 1807 (PPL) for the following functions:

    • The transmission of messages
    • Status
    • Diagnostic information