Abstract: The engine ignition circuit on a motor vehicle is controlled by an electronic switch which is part of a receiver/controller unit on the vehicle. A separate self-contained transmitter unit generates a seven digit coded address at a certain baud rate which modulates an RF carrier of a certain frequency. In the receiver/controller unit, if the baud rate and the carrier frequency of the transmitted signal are correct, the coded address is compared with a stored coded address. If they match, the electronic switch is closed, enabling the vehicle engine to be started. The usual ignition switch on the vehicle must be closed before the receiver/controller unit can be effective. The receiver/controller unit remains on for a minute or two after the ignition switch is opened.