Kraftfahrzeugalarmanlage und Verfahren zum Betrieb einer solchen

The system has a sensor arrangement for detecting penetration into a vehicle or damage to the vehicle, a controller connected to the sensing arrangement and an acoustic warning device connected to the controller that can be driven by the controller depending on the signals from the sensing arrangement. An additional acoustic output unit is provided in the vehicle. A checking device checks the functionality of the activated warning device and sends a corresponding signal to the controller to enable operation of the additional acoustic output unit if the driven warning device cannot be operated. Independent claims are also included for the following: a method of operating a motor vehicle alarm system.