Abstract: Apparatus for disabling operation of a vehicle in the event of an attempted theft thereof. A switch is provided in the ignition circuit. The switch is controlled by a processor which is remotely-controllable to open the ignition circuit to prevent the passage of current therethrough. This switch is thus controllable independently of whether the vehicle is in operation whereby the vehicle may be rendered inoperative even after it is discovered that the vehicle has been driven away by a thief.

Abstract: Alarm apparatus which generates a repetitive sound wave having at least two pulses of predetermined frequencies within a predetermined interval of time. A resonator generates the clock frequency therefor. The resonator may have a low tolerance of less than about 0.1 percent so that at least two pulses may be detected by a receiver having a similarly low tolerance so that false triggering of the receiver by other transmitters or background noise may be prevented. A plug is inserted into the alarm housing to maintain circuitry for initiating operation thereof open. Pulling of the plug from the housing allows the circuitry to close to initiate operation of the alarm. A push button is provided on the end of the plug to close the circuitry for initiating operation of the alarm while the plug is inserted into the apparatus. Once the alarm has been initiated, the circuitry is such that the alarm cannot be inactivated except by removal of the internal power source.