GM Service Manual Online
For 1990-2009 cars only

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.