Abstract: A vehicle alarm system with a sensor for detecting a change in the alarm system from an armed not triggered state to an armed triggered state, an override switch operable only when the alarm system is in the armed triggered state, to stop the alarm from sounding in the armed triggered state, an ignition switch, an ignition sensor, and a controller for switching the alarm system from the armed triggered state to the disarmed state when the ignition sensor supplies a signal indicating ignition on while a timing circuit is activated and maintaining the alarm system in an armed triggered state when no ingition signal is supplied while the timing circuit is activated.

Abstract: An upgrade method and apparatus for both remote and key-operated two-step vehicle security systems is disclosed. The upgrade blocks attempts to disarm the alarm circuit when the vehicle is armed and unlocked improperly.The upgrade can be added to existing systems regardless of the polarity of the signals used therein. Improved power-up and remote control features can also be added as a part of the upgrade.

Abstract: An enhanced vehicle remote control system adds a new transmitter and a new receiver to an original remote control system. The new receiver is connected for direct operation of the original transmitter which is permanently installed in the vehicle. In response to signals from the original transmitter, the unmodified original receiver controls the same functions in the same way as before. The new receiver is also connected to control functions in the vehicle which were not controlled by the original remote control system.

Abstract: A security system for a vehicle having an engine compartment covered by a hood, and an ignition switch for operating the engine, includes a common housing for protecting a hood lock and an ignition lock switch. An electric circuit is provided for shorting an ignition coil during periods of non-use of the vehicle to prevent theft of the vehicle, the circuit being disarmed by the lock switch for a sufficient interval of time to permit use of the ignition switch for starting the engine. A lock-up feature within the circuit maintains the circuit in the disarmed state during operation of the vehicle, and automatically rearms the circuit upon retrieval of the ignition key.