The locking system effectively prevents vehicle theft and unauthorized access to the interior. That’s why certain locking devices and security systems have been used since the very beginning of automotive engineering. Now learn all about the components of the locking system and how they work.

The car’s locking system

The locking system of a car ensures that only authorized persons can use the vehicle. Unauthorized persons are denied access. Locks on all doors and flaps of the car have proven to be an effective means of doing this. The system also prevents vehicles from being put into operation without authorization. A locking system in the automotive sector is made up of numerous parts.

• Vehicle key
• Lock cylinder
• Door lock
• Ignition lock
• Steering wheel lock

Vehicle key

The vehicle key is used to unlock and lock the vehicle locks. In many vehicles, the engine is also started by means of a key. Older vehicles sometimes have several different keys for the gas cap, doors, ignition lock or glove compartment. In modern vehicles, all locks can be closed with a common vehicle key. The remote control for the central locking system is often integrated into the vehicle key, as is a button for opening the trunk.

Lock cylinder

A locking cylinder is the heart of a mechanically operated security lock. The cylinder usually consists of a cylinder housing and a rotating cylinder core. The locking cylinder can only be operated and turned to unlock the lock with the appropriate key. For this purpose, vehicle keys are provided with grooves, flutes or holes, depending on the manufacturer and vehicle generation. Depending on the vehicle model and the locking mechanism, the lock is operated or the central locking system is activated via the locking cylinder.

Door lock

In cars, the term door lock does not refer to the lock for locking the door, but to its locking mechanism. The door lock ensures the secure locking of the vehicle door. Sometimes it is a combination of a locking mechanism for closing the door while driving and a locking system. When the car door is closed, the door lock securely locks it and prevents unintentional opening while driving. Unlocking is usually done mechanically via an operating linkage or a Bowden cable via the door handles.

Ignition lock

The ignition lock is one of the oldest security devices in automotive engineering. It protects the vehicle against unauthorized use by ensuring that the engine can only be started via the ignition lock. The key can only be pulled out of the lock when the ignition is deactivated. In the case of a diesel, which does not require ignition, the ignition lock interrupts systems such as the fuel supply instead. After inserting the key, the ignition is gradually activated by turning it and then the engine is started.

Steering wheel lock

A steering wheel lock prevents the vehicle’s steering wheel from being turned. This makes the lock, known as a steering wheel lock, one of the most effective and widespread security devices for vehicles. As a rule, the steering wheel lock on passenger cars is combined with the ignition lock to form a single unit. When the driver pulls the key out of the lock, a bolt slides into a groove in the steering. Modern vehicles sometimes have an electronic steering wheel lock, in which the steering is blocked by means of electric actuators.

Central locking

A central locking system allows the driver of a car to unlock or lock all vehicle doors simultaneously. This is done either by turning the key in the locking cylinder of the vehicle door, or by using a remote control belonging to the vehicle. Various components make this practical function possible.

• Central locking control unit
• Pump for the central locking system
• Central locking control unit
• Central locking remote control

Central locking control unit

The central locking control unit controls and monitors all functions of the central locking system. In many modern vehicles, additional control units are also installed for each door, which communicate with the central control unit. In addition, the control unit implements the commands that the driver specifies using the remote control. The door locks, the trunk locking system and all actuators are also controlled from the control unit. If the control unit is defective, the central locking function is not available.

Pump for the central locking system

Many central locking systems in older vehicles work with a vacuum system. Here, negative pressure ensures that the door locks are opened and closed via the central locking system. The required vacuum is generated by a vacuum pump. In some vehicle models, this pump of the central locking system is also responsible for the closing function of the doors, the smooth closing of the trunk, the trunk opening or the seat adjustment. Often the pump is defective or leaking, but it can be easily replaced with a spare part.

Actuating element of the central locking system

Modern central locking systems often work completely electronically. Instead of a cumbersome locking of the doors by means of vacuum or other pneumatic systems, electric actuators are used here. These are servomotors, i.e. small electric motors that operate the door locking mechanism. When the driver presses the radio transmitter or turns the key in the door lock, the actuators are activated. Some systems also allow individual doors to be locked from the inside.

Remote control for central locking

Many modern cars have a remote control that the driver can use to unlock or lock the vehicle. In each case, this is possible from a certain distance, and there should be visual contact with the vehicle. Remote controls with infrared transmitters can only bridge short distances, while radio remote controls work at greater distances. Depending on the model, the remote control for the central locking system is either separate or integrated into the vehicle key in the form of buttons.

Electronic immobilizer

An electronic immobilizer is a security device designed to make it more difficult or impossible to steal a vehicle. To do this, the immobilizer interrupts the ignition, the fuel supply or blocks the starter motor to prevent the engine from starting.

• Control unit of the immobilizer
• Transponder for immobilizer

Immobilizer control unit

The immobilizer control unit is the central unit of the electronic safety system. The control unit monitors all functions of the security system and activates the immobilizer devices. This happens automatically when the ignition key is removed from the ignition lock, or when the driver leaves with the key.

Electronic transponder

Another important element of the electronic immobilizer is the transponder. A small communication device, the transponder is usually integrated directly into the vehicle’s key. When the vehicle key is inserted into the ignition lock, the chip installed is uniquely identified. Only if this identification is correct does the electronic immobilizer release the car.

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