Automotive keys are used to open and start vehicles.The mechanical blasde has remained a feature for many years as a first line of security for the vehicle, and, in modern cars, if the central locking remote control fails.
Advances in technology have resulted in the use of Transponder Immobiliser Systems, which have increased considerably in complexity as time has gone by. Basically this system involves the inclusion of a small transponder chip placed inside the ignition key.
The inclusion of transponders in vehicles means that, whenever additional or replacement keys are required, they must be programmed into the vehicle using specialist diagnostic equipment.
Transponder is short for transmitter + responder. In basic terms, a transponder is a miniaturised electronic chip that has Non Volatile Memory; ie the memory is not dependent on a constant supply of energy for its retention.
The process of key identification is similar in most automotive transponder systems. Once a key is inserted into the ignition lock and turned to one of the on or run positions, the induction coil which is mounted around the ignition lock sends out an electromagnetic field of energy. The windings in the transponder chip absorb that energy and power the electrinic chip to emit a signal. The induction coil reads the signal. If the signal is recognised as being already in the computer’s memory, the signal is accepted and other electronic components in the vehicle are set in motion to allow the starting of the vehicle.
Transponder system types may be fixed code or rolling code. The rolling code system changes each time the transponder is activated and may also contain additional information such as the vehicle identification number (VIN).
Central locking remote controls come in all shapes and sizes and with varying numbers of buttons which may control, not just the central locking system, but also the lights, windows, boot/tailgate opening, individual door opening, panic button and other alarm functions.
Keyless entry or proximity versions are now becoming more popular. This is where the buttons on the remote control do not need to be pressed to open the vehicle, but, when the remote control is within a set distance of the vehicle, the central locking will operate and, as long as the remote control is within the vehicle, a button can be used to start the engine.