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What is the central locking system/what does it do?
Central Locking systems are common or at least an option on most modern cars. It enables remote locking or unlocking of all doors from a key fob or from switches inside of the vehicle. This operation also functions with the insertion and turning of the key in the driver's and the front passenger door.
Getting into the details of the central locking system
On earlier makes and models that offered central locking the system was powered by a vacuum system. In general, modern makes and models are operated through the use of small electric motors and gears in an actuator, one of which is positioned inside each door cavity below the door lock lever pull rod and adjacent to the rear door closure on the hatchback or estate. The central locking system can be part of the security system controlled by the ECU (electronic control unit) which is part of the vehicle's computer system. Apart from controlling the central locking it may also control ignition lock, steering lock, alarm and immobilizer. Some ECUs also control automatic window closure, fuel flap locks and car vehicle tracking.
The system can consist of a separate control unit which picks up a radio signal pulse code from a preset key fob. Wired to the control unit are the actuators which run when the signal is received and push up the lock rod and open the lock. When the lock button on the fob is pressed the small electric motors run in the opposite direction and the actuator pulls the lock rod down. On some models the fob and control unit are programed and wired to control interior lights to switch on and remain on until the engine is started. Sometimes using the central locking can also activate or deactivate the alarm system.
The control of central locking is usually a two way switch on the center console or within the facia of the front doors, to open or close the locks on all the doors simultaneously . On some makes and models when locking the doors, any windows that are open will also close. There are also individual switches on each door that will operate that particular door.
What if something goes wrong with the central locking system?
Spares for the electric central locking system include actuators, control units, switches and key fobs. On older air vacuum systems they can include vacuum pumps and vacuum actuators.