In an effort to reduce theft, some vehicle manufacturers fit very sophisticated theft deterrent systems to their vehicles.
Theft deterrent systems can be divided into four different categories. Component identification; vehicle locking; engine and transmission immobilization; and audible alarms.
Visible identification of major components can be a deterrent for theft. Some manufacturers have etched the Vehicle Identification or VIN Number onto labels that are attached to various components on the vehicle such as fenders, doors, the hood and trunk as well as major mechanical components such as the engine and transmission.
Etching the Vehicle Identification Number onto all windows with a small sand blaster is unobtrusive and makes the vehicle less attractive to steal. If the vehicle is resold or used for parts the monetary value is reduced.
Microdots are small plastic particles that can have either the VIN or a unique number printed on to them. They are almost invisible to the naked eye, but can be seen by using an ultra-violet light and a magnifying glass. They are mixed with an adhesive and sprayed onto the underside of the vehicle, into the wheel wells and engine bay. A small transfer affixed to the vehicle displays that this system has been used, making the vehicle less attractive to a thief.
Door lock systems can be manual entry, where a key has to be inserted into the door lock and turned; or keyless, where a button on the key or key fob is pressed; or the door unlocks automatically as a driver carrying the correct security device approaches the vehicle.
On older vehicles, turning the key in the door lock would unlock only that door. The remaining doors needed to be unlocked manually, via the lock snib or lever. Releasing the key would return it to the same position it was in when inserted so it could be removed.
When central locking was introduced, the lock mechanism on the drivers door had a micro switch that, when turned, would activate electric solenoids on the remaining doors and trunk and unlock them. The same applies when the doors were locked.
Further enhancement allowed manufacturers to introduce a security system that automatically locked the doors once the vehicle had reached a preset speed. This feature is mandatory in some countries.
Dead locking adds a further level of security, so that if the key were turned a quarter turn and removed a second micro switch activates small electric motors in each door lock mechanism, mechanically locking them.
