Abstract: The primary object of the present invention is to provide an alarm system which is capable of being set off prior to any damage being done to the motor vehicle by an intruder. Thus, an intruder who merely shines a flashlight into the dashboard area of the vehicle to determine whether or not there is a radio, stereo, or other valuable item to be taken, will set off the present invention alarm system prior to actually breaking into the vehicle. Thus, the present invention is directed to a motor vehicle alarm system which is designed to respond to the intrusion of light and which incldues a physical enclosure for placement in the inside area of a motor vehicle which has a faceplate with at least one aperture through which intruding light may enter, as well as an intruding light detecting means within the enclosure which is located at the aperture. A signal generating means is connected to the intruding light detecting means so as to generate a signal in respose to a preset level of intruding light.