Table of contents: ABS / Emergency brake booster… ↓ Notes on ABS/EBV/EDV systems ↓
The brake system consists of a master cylinder, a brake booster, and disc brakes on the front and rear wheels. The hydraulic brake system has two circuits that operate diagonally. One circuit acts on the front right/rear left brakes, the second circuit acts on the front left/rear right brakes. If one of the circuits fails, for example, due to a fluid leak, the car is braked by the other circuit. The fluid pressure in both circuits is created by a dual master cylinder, which operates from the brake pedal.
The brake fluid reservoir is located in the engine compartment, above the master cylinder. It supplies the entire system with brake fluid.
The brake booster in a gasoline engine accumulates part of the vacuum created in the engine's intake manifold. When the brake pedal is pressed, the force on it is reduced due to the amplifying effect of the vacuum. Since the diesel engine does not have the necessary vacuum at the intake, diesel models have a special vacuum pump. The vacuum pump is mounted at the front of the cylinder head and is driven by the camshaft.
The car has disc brakes with a floating caliper caliper both in the front and rear. With this design, one piston ensures that both brake pads are pressed against the brake disc.
Warning: When driving on wet roads, it is necessary to periodically press the brake pedal to dry the disc brakes. Due to the centrifugal force that occurs during the movement of the car, water is thrown off the discs. However, a thin film of rubber wear products, grease and dirt remains, preventing the brakes from operating effectively.
Dirt and water on the surface of the brake pads cause grooves to form on the surface of the brake discs, which reduces braking efficiency.
When cleaning the brake system, dust is released that can be harmful to human health, so inhaling brake dust is not recommended.
ABS / Emergency brake booster /EBV/EDS
Work with electronically controlled elements of the braking and driving systems is permitted only to be performed by specialists with appropriate training.
ABS: The anti-lock braking system prevents the wheels from locking when the car is braking sharply. This helps maintain control of the car during braking and increases driving safety.
Emergency Brake Assist: The electronic power steering system recognizes an emergency situation based on the speed of the brake pedal and the pressure on the pedal. In such a situation, the power steering automatically increases the brake pressure set by the driver within milliseconds to the limit of wheel locking.
EBV: The electronic brake force distribution system distributes the braking force between the front and rear wheels using ABS hydraulics. Since the electronic EBV system is significantly more sensitive than a mechanical brake force regulator, a significantly larger control range is used.
When driving straight ahead, the rear brakes are fully engaged in the braking process. To ensure vehicle stability also when braking on bends, the rear brakes must be reduced in their engagement in the braking process. The ABS speed sensors provide the EBV with information about whether the vehicle is driving straight ahead or turning. When turning, the braking action of the rear brakes is reduced. This allows the rear wheels to maintain maximum lateral grip on the road.
EDS: Electronically locking differential, when starting off, brakes the spinning wheels. Due to this, the torque is redistributed to the "pulling" wheels.
The electronic differential lock operates when starting off and switches off automatically when the speed reaches 40 km/h. The advantages of this system are the absence of a negative impact on driving performance and maintaining control comfort when starting off.
Notes on ABS/EBV/EDV systems
A safety circuit in the electronic control unit ensures that if the system detects any defect, (for example, a cable break) or when the operating voltage is too low (battery voltage below 10V) switched off by itself. This is indicated on the instrument panel by the control lamps lighting up. The normal braking system remains operational. When braking, the car behaves as if there is no ABS.
Warning: If the ABS and brake system warning lights are on while driving, the rear wheels will lock up under heavy braking because the brake force distribution is out of order.
If the ABS warning light comes on while driving:
1. Stop the car, turn off the engine and start it again.
2. Check the battery voltage. If the voltage is below 10.5 V, charge the battery.
Caution: If the warning lights come on when you start driving and go out after a while, this indicates that the battery voltage was initially too low. It then increases due to the battery being charged by the alternator.
3. Check that the battery terminals are securely fastened and that there is good contact.
4. Raise and place the vehicle on stands, remove the wheels and check the electrical wires of the speed sensors for external damage (places of chafing). A more thorough check of the ABS/EBV/EDV systems should be carried out at a service station.
Warning: Before carrying out electric welding work, it is necessary to disconnect the connector of the hydraulic control unit in the engine compartment. The connector is disconnected with the ignition off. When painting, the control unit can be briefly exposed to temperatures no higher than +95°C and for a longer time (no more than 2 hours) temperature not exceeding +85°C.