Many motorists, for the sake of convenience and practicality, install a central lock on their cars, if one is missing in the configuration. This is a very necessary device, since with the help of this system the doors of the car and the trunk are unlocked and closed completely in automatic mode. You won’t surprise anyone on new cars, but for older cars this is a great option.
Device
The central castle is arranged as follows. This electronic control unit, actuators, control panel and wiring.
Actuators are electric drives that can be built directly into the door lock or installed separately. Actuators can be either mechanical or pneumatic.
How it works?
All this works according to one principle, regardless of the type of lock. When the driver turns the door lock key, the control group of contacts closes, giving a command to the control unit. He, in turn, transfers it to the locking devices of the doors, trunk, and sometimes the hatch of the tank. If a traffic accident occurs or airbags are deployed, advanced systems will unlock all doors automatically.
The main types
Fundamentally, the central lock can be of two types. This is an electrically driven system as well as a pneumatic solution. Consider the features of each type.
Power Door Locks
Electric activators are installed in the car doors under the door card. In various imported cars, the lock may already be equipped with an electric drive. Often, each of the actuators is controlled from a single unit. But there are advanced models where each activator is controlled from a separate unit. On budget models, most often you can find a castle of this type.
The drive is a small electric motor and gearbox. The activator is equipped with a mounting kit and traction. According to manufacturers, one such device is capable of generating an effort of up to four kilograms.
You can distinguish systems with a negative control wire and with a positive one. What is the control signal and how such locks work, we will consider below.
Pneumatic lock
This solution is already much more complicated technically. Most often, such a central lock was installed on expensive car models. They are still found in older Mercedes models. This system works by changing the air pressure inside special lines. Since the locking system with a pneumatic drive is very outdated, it is now unprofitable and by and large impossible to restore it due to the lack of new spare parts and at least some accurate information.
The simplest electric central lock
In most budget-class cars, a five-wire actuator can be seen in the driver's door. Sometimes manufacturers who want to save money do not install one, but put only a button.
In the electrical circuit there are limit switches, activators, a control unit. So, when you turn the driver’s door key to close / open, a short signal with a negative potential is applied to the control unit from the limit switch. In addition to the trailer door, there are the same on the passenger.
Next are the servos. For their work you need only two wires. They are both power. The central lock is connected in such a way that, to start the servo drive or actuator, it is enough that the potentials on the control wires change. Depending on which of the wires is positive and which is negative, the servo will work in one or the other direction.
Connection
For installation on low-cost cars, many now buy inexpensive kits. Using control units of this type, it is possible to equip an existing system with remote control or to connect a central lock, if before that it was not on the car. Naturally, the system only allows you to open / close the car with the remote control.
If you press the button on the complete key fob, the drive will simulate the physical rotation of the key in the lock to open or close the door. Receiving a signal, the unit supplies the appropriate voltage to the power wires. The central locking control unit in this form is used to operate only 6 wires.
This is a permanent plus wire. For safety, protected by a fuse. There is also a constant mass. Then two power wires are connected to the unit, which then go to the servos, and two control wires. There are other contacts. They serve for light indication, closers for glasses and other functions. A separate button allows you to open the trunk or gas tank flap. Additional options are available depending on which central locking control unit is available - they are all different and equipped with various additional functions.
And now let's go directly to the connection. The positive wire is connected either to the battery or connected to the plus in the fuse box - it is much more convenient. The amount of energy consumed depends on how much power the activators have and how many of them. Any bolt or any part in contact with the body is suitable as a mass. The positive lead is usually connected through the central locking fuse provided.
A blue wire comes off the control unit to open or close the boot lid. When you press the corresponding button on the remote control, a negative pulse will appear on the wire. The trunk is connected using a four-contact relay. If you connect a brown wire with a wire of dimensions, then the closing / opening process will be accompanied by a blinking of headlights. The green wire must be connected to the glass closers. However, usually when installing a central lock, this wire is ignored.
Without exception, it is advisable to stretch the wires through the corrugation, in which there is already all the other wiring in the car. It performs not only an insulating function, but also protects the wires from abrasion.
The whole connection process is reduced to connecting the wires, connecting the terminal to the control unit. The wires to the actuators are connected through convenient connectors. The scheme is simple - even beginners are able to collect it. The process of installing actuators on the door is also simple - it is important to mount them so that the traction can be effectively pulled by the traction on the lock. Convenient fasteners and self-tapping screws come with actuators - you can install the device on the door as quickly and reliably as possible.
In order not to make a mistake when connecting, a convenient and understandable instruction of the central lock is attached to each model. It shows how to connect all the wires to the unit.
Connect central lock to alarm
Often, alarm systems do not include actuators for controlling door locks. But there is a lock control function. Let's see how to connect the lock to the alarm.
Before connecting the lock, you need to find out what type it is. It is important whether the impulse will be the governing one - positive or negative. In the first case, the doors will open if a plus is supplied to the control wire, in the second case - minus.
To find the necessary wires during the installation of the central lock, you will need a special probe. This is a piece of wire and a light bulb. With this simple device you can find exactly what you need. On one of the wires at the time of opening there should be a minus, on the second minus should be at the time of closing. Then everything is connected according to the scheme, which is in the instructions for the alarm.
During the connection, do not forget about security. It is important to install a central locking fuse and to insulate all connections. If you abandon the insulation, then even a small drop of water will cause a complete failure of the system.
Typical malfunctions
There are not many specific faults. The system may fail completely - in this case there will be no reaction to keystrokes on the key fob. No commands will come to the control unit. Often the reason is commonplace - this is a dead battery in the key fob. Therefore, if the central lock does not work, it is worth checking the batteries first.
Also, the system can only partially fail. In this case, periods of normal operation and total failure will be observed. In addition, locks can work in a chaotic mode. They can live their own lives - independently open doors, block. There is no reaction to user actions. This can be dangerous, as the doors may close without an adequate ability to open them.
There may be wire breaks in the circuit. Various sloppy actions could disrupt contact. If it does not close the central lock, then it is entirely possible that the reason is precisely a cliff. Relays in the control unit may also fail. If the device is inexpensive, it’s easier and cheaper to buy a new unit. Often, these products are poorly repairable.
Conclusion
So, we found out what a central castle is. As you can see, you can connect it with your own hands.