Abstract: An anti-theft device for an automobile audio system automatically prevents the audio system from functioning whenever the audio system is removed from its authorized vehicle and placed into another vehicle. This anti-theft device includes a microprocessor which operates with a bus interface for communicating a vehicle identifier from a vehicle multiplex bus to the central microprocessor. The device also has non-volatile memory within which the first received or authorized vehicle identifier is stored. The subsequently received identifiers are stored on RAM. A battery detector connected to the microprocessor alerts the microprocessor whenever the audio system has been disconnected from the battery source.

Abstract: A radio speaker short circuit detection system for a vehicle visually indicates a speaker short circuit failure. A microprocessor receives a short circuit failure signal from a short circuit detection circuit. Short circuit failure data can be stored for future diagnostic retrieval.

Abstract: In a vacuum fluorescent display tri-compatible dimming system, a dimming signal can be sent in the form of a multiplex bus message, an analog DC voltage signal, or a pulse width modulated signal. Each form of dimming is accepted by a microprocessor of a lighted automotive module, such as a radio, however, the multiplex bus message takes priority. The microprocessor then sends a dimming signal to the vacuum fluorescent display via a vacuum fluorescent display driver IC.

Abstract: A multiplex bus that is corrected to an AM/FM/CD radio. The multiplex bus couples communicating microprocessors in modules, including a body computer, an engine controller, a transmission controller, and other functional components of an automobile. The radio includes components for audio amplified clipping detection and remote control of the volume. The computer controls the volume and clipping features via the multiplex bus. These features, and the programming of the computer with respect to the features are controllable by diagnostic tools external to the system, which may by hooked up to the bus in an assembly plant or an automobile service center. So programmed, the body computer is be able to read the vehicle speed, rpm, transmission gear, and acceleration and decide, in accordance with a predetermined algorithm or programmed instructions, whether to increase or decrease the radio volume. The decision depends on the vehicle characteristics and/or the preference of the prime listener.

Abstract: An illumination mechanism is provided for the receiving opening of an automobile entertainment device. The mechanism includes at least one light pipe fitted in the face of the entertainment device in close proximity to the area to be illuminated. This light pipe extends to a lamp or other light source otherwise used in the automobile for other illumination.

Abstract: In an adjustable clip detection system, an audio output signal is sent from a volume control integrated circuit to an amplifier. The output of the amplifier is received by a clip detection circuit. The clip detection circuit monitors the audio output from the amplifier for clipping distortion. If clipping is detected, the clip detection circuit sends a signal to a microprocessor. The microprocessor then sends a signal to a volume control integrated circuit to decrease the voltage level of the audio output until clipping is no longer detected. The amount of attenuation that the microprocessor instructs the volume control integrated circuit to perform is determined by a predetermined programmed parameter. The amount of attenuation to be performed by the volume control integrated circuit can be adjusted by sending the microprocessor a formatted message, through a multiplex bus, corresponding to the predetermined program parameter located in a look-up table.