GM Service Manual Online
For 1990-2009 cars

All audible warnings are generated by the radio and through the radio amplifier when equipped. All such warnings are provided to the radio via messages on the class 2 serial data line. The following class 2 messages, which produce the required chimes, are controlled by the Body Control Module (BCM).

    • The key in ignition chime class 2 message.
    • The lamps on chime class 2 message.
    • The fasten belts chime class 2 message.
    • The parking brake on chime class 2 message.
    •  Each of these has an associated IPC Indicator tell tale.