Many motorists, for the sake of convenience and practicality, install a central lock on their cars, if one is not included 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 automatically. On new cars, this is not surprising, but for older cars, this is a great option.
The central lock is arranged as follows. This is an electronic control unit, actuators, control panel and wiring.
Actuators are electric actuators that can be built directly into the door lock or installed separately. Actuators can be either mechanical or pneumatic.
How does it work?
It all works on the same principle, regardless of the type of lock. When the driver turns the door lock key, the controla group of contacts that sends a command to the control unit. He, in turn, transfers it to the locking devices of the doors, trunk, and sometimes the tank hatch. In the event of an accident or airbag deployment, advanced systems unlock all doors automatically.
Fundamentally, the central lock can be of two types. It is an electrically driven system as well as a pneumatic solution. Consider the features of each type.
Electric central locking
Electrical 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 executive devices is controlled from one unit. But there are advanced models where each activator is controlled from a separate unit. On budget models, you can most often find this type of lock.
The drive is a small electric motor and gearbox. The activator is completed with a mounting kit and a rod. According to manufacturers, one such device is capable of generating up to four kilograms of force.
You can distinguish systems with a negative control wire and a positive one. What is a control signal and how such locks work, we will consider below.
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. Worksthis system by changing the air pressure inside special lines. Since the pneumatically actuated locking system is very outdated, it is now unprofitable and largely unrealistic to restore it due to the lack of new spare parts and at least some accurate information.
The simplest electric CH
In most budget cars, you can see an actuator with five wires in the driver's door. Sometimes manufacturers who want to save money do not install this, but only put a button.
In the electrical circuit there are limit switches, activators, a control unit. So, when the driver's door key is turned to close / open, a short signal with a negative potential is sent to the control unit from the limit switch. In addition to the driver's door limit switch, there are the same ones on the passenger doors.
Next are the servos. They only need two wires to work. They are both powerful. The connection of the central lock is carried out in such a way that to start the servo or actuator it is enough that the potentials change on the control wires. Depending on which of the wires is positive and which is negative, the servo will work in one direction or the other.
To install on budget cars, many people now buy inexpensive kits. With the help of control units of this type, it is possible to equip an existing system with a remote control or to connect a central lock, if it is already on the cardid not have. 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 positive wire. Protected by a fuse for safety. There is also a constant mass. Then two power wires are connected to the block, which then go to the servos, and two control wires. There are other contacts as well. They serve for light indication, glass closers and other functions. With a separate button, you can open the trunk or the gas tank hatch. Additional options are available depending on which central locking control unit is available - they are all different and equipped with different 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 - this is much more convenient. The amount of energy consumption depends on how much power the activators have and how many there are. Any bolt or any part that has contact with the body is suitable as a mass. The positive wire is usually connected through the central locking fuse included in the kit.
A blue wire comes out from the control unit for opening or closing the trunk lid. When you pressthe corresponding button on the remote control, a negative pulse will appear on the wire. The trunk is connected using a four-pin relay. If you connect a brown wire with a wire of dimensions, then the process of closing / opening will be accompanied by flashing headlights. The green wire must be connected to the glass closers. However, this wire is usually ignored when installing a central lock.
Without exception, it is advisable to pull the wires through the corrugation, in which there is already all the rest of the wiring in the car. It performs not only an insulating function, but also protects the wires from abrasion.
The whole connection process comes down to connecting wires, connecting the terminal to the control unit. The wires to the actuators are connected through convenient connectors. The scheme is simple - even beginners can assemble it. The process of installing the actuators on the door is also simple - it is important to mount them so that the rod can effectively pull on the rod on the lock. The actuators come with convenient fasteners and self-tapping screws - you can install the device on the door as quickly and reliably as possible.
In order not to make a mistake when connecting, each model comes with a convenient and understandable instruction for the central lock. It shows how to connect all the wires to the block.
Connect the central lock to the alarm
Often, alarm systems do not come with actuators to control door locks. But there is a lock control function. Let's see how to connect the lock to the alarm.
Before you connect the lock, you need to find out whichhe's like. It is important which impulse will be controlling - positive or negative. In the first case, the doors will open if a plus is applied 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 tool you can find exactly what you need. On one of the wires at the moment of opening there should be a minus, on the second one there should be a minus at the moment of closing. Then everything is connected according to the scheme, which is in the instructions for the alarm.
In the connection process, do not forget about security. It is important to install a central locking fuse, as well as insulate all connections. If the insulation is abandoned, even a small drop of water will cause a complete failure of the system.
There are not many specific faults. The system may fail completely - in this case there will be no reaction to pressing the keys on the key fob. Commands will not be sent to the control unit. Often the reason is banal - it's a dead battery in the key fob. Therefore, if the central lock does not work, the first thing to do is to check the batteries.
Also, the system may fail only partially. In this case, there will be periods of normal operation and total failure. In addition, locks can work in a chaotic mode. They can live their own lives - open doors on their own, block themselves. In this case, there is no reaction to user actions. It could bedangerous as doors may close without adequate ability to open them.
Possible broken wires in the circuit. Various inaccurate actions could break contact. If the central lock does not close, then it is quite possible that the reason is precisely in the cliff. Also, the relay in the control unit may fail. If the device is inexpensive, then it is easier and cheaper to buy a new unit. Often these products are poorly repairable.
So we figured out what a central lock is. As you can see, you can connect it yourself.