Components and Features of Central Locking System

Central locking

The main function of the central locking system is handling access authorization all the time but it addittionally must cover the next areas: actuation of starting holders or lifting, braking and locking the gates during closing operation.

The central locking system includes pursuing components:

-locking bars on your body pillars,

-doors, door lock mechanism and dedicated mechanised and electro-mechanical parts,

-electrical components - necessary to access authorization center and radio handy remote control.

Depending on the location further dividing being made

-side door assembly,

-trunk assemblage,

-hood assembly,

Illustration 1: Central locking system schematic

Door assembly involves catch, pawl and latch. The door lock striker is attached to the body pillar. Under shutting operation the entranceway lock striker gets trapped by the latch and maintain in the shut down position and centres the door. The pawl positively locks the catch constantly in place. This lock condition is automatically aborted when opening procedures begin. For this process the pushes acting on inner or outside door take care of are used in the pawl and cause the get release to start the door. The door lock striker stays in the positioning while the catch swivels get into an wide open position.

In a case of operation methods central locking system consists of two types of actuators: electromagnetic and pneumatic.

Electromagnetic actuators count on solenoids which lock or unlock entrances using current moving in both directions (wide open/closed) through an electric module. On this kind of system two types of agreements are used. First one uses individual relays for each and every of action taking by the machine. One focused on open and a different one to close the entranceway. Both of them are controlled with a transistor moving over the circuit controlled by the capacitor (safe-keeping for energy essential to operate system) which is liberating current essential to activate the hair. Another type uses two capacitors and two relays working as a tandem. One match is in charge of locking and another for unlocking. If the circuit is shut down a current is discharged from the capacitor and the lock is either exposed or finished.


Pneumatic actuators are driven by way of a pneumatic central unit which manages vacuum/pressure pump. When vacuum is applied actuators acting on device lock or uncover the door. The vacuum pump is driven by electric electric motor which is employed in both directions. Forward rotation creates a compressor action (entry doors open up), while backwards rotation creates vacuum (entry doors close). Polarity on the electric motor unit is changed by a change-over control turn.


In most modern cars electrical power locking system changed mechanical unit due to a demand for quality and trustworthiness. The main benefits of electro-mechanical locking system are

-symmetrical design,

-smaller and lighter in comparison to a mechanised unit

-only one lock version per vehicle

-individually encoding by the end of the creation line

-door handles no longer move

Other supplementary functions, like an interior light or position indicator, can be easily introduced in electrical power locking system because the lock is equipped with gadgets, which can perform these functions. Communications with the locks, power and security system happen via data can bus system.

Engine immobilisers

An immobiliser is an digital anti-theft security device which stops engine begin by an unauthorised person unless the correct key or fob is put in the ignition barrel. If the correct key can be used, transponder inside the key sends a sign to the audience which transfer signal to the device (ECU). If the signal is accepted by the ECU, the machine allows user to begin engine motor. If not the immobiliser disables few car systems necessary to get started on the engine: usually it is gasoline injection, fuel pump and ignition components.

The immobiliser is firmly connected to the automobile security system, so any unauthorised usage of the car that is discovered by the security system (movements detectors, infra-red sensor, sonic sensor and many others, depending on security system) automatically trigger the immobiliser and other alarm aims such a horn and flashing headlights.

Car security alarm can be triggered by infra-red transmission produced by the fob or an integral diamond ring and received by optical sensing device placed anywhere in the automobile. Another type is a radio control system. Radio influx is established by the fob or the key and received by car antenna - frequently a car warmed rear windows. In both cases the signal is exclusive for every car in support of this one indication is recognised by the ECU.

Alarm system uses few different types of sensors to protect the car

-shock sensor: discovering any vehicle moment

-ultrasonic: car interior is included in an ultrasonic indication; any change in the durability on the indication pattern activates the alarm

-voltage drop or current drain: any drop of voltage (disconnecting the battery pack) or current drain (by moving over on interior light)

-infra-red: detecting any disruption of the beam sent between two items within the car

-direct globe contact: recognized by the bonnet, shoe and door switches when an globe contact happens

Diagnosis and repair defect.

Make: Vauxhall

Model: Vectra B

Year: 1999

After connecting central locking rig to the electric battery I pointed out that the locking system does not work properly. First of all, I checked voltage on the electric battery, unfortunately it was too low: -12v. To rectify this I connected the power to the charger. Since then the central locking system starts to execute quickly and properly. After some time the system ceased working completely. It didn't respond to the automobile key fob. First, I examined the power voltage inside the key. Multimeter revealed the voltage of 3v (battery pack type-CR2032), which is completely perfect.

I was looking meticulously in to the key fob for any damage on the electric circuit or power supply holders, but everything is at an effective working order.

After that I measured the resistance of every door and readings on multimeter were as follow

Nsf-1 ohm,

Osf-1 ohm,

Nsr-1 ohm,

Osr-1 ohm,

According to the Autodata all readings matched the manufacturing plant range. To make certain about my conclusions I examined continuity on each one of the door and this established my thought that wiring between your gates and the central device is within a good working order. Previous part of my diagnostics was looking at the condition of the central device itself.

Firstly, I linked the multimeter to the dock No2 and No8 to check voltage transferred from the battery pack to the central locking device. Sadly the voltage was 0v. I QUICKLY examined continuity on the wiring between the central locking device and the battery pack. There is no continuity at all.

My prognosis: The wiring between the power supply and the central locking device is faulty. To rectify this the faulty wiring needs to be replaced.

Electrical circuit diagram

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