Anti-lock braking system (ABS)
The installed ABS system was developed by Bosch. The anti-lock braking system (ABS) consists of an electronic control unit and hydraulics, an ABS warning light on the instrument panel, wheel speed sensors, and gears that read wheel rotation pulses.
The anti-lock braking system prevents the wheels from locking during sudden braking. Thanks to this, the car remains controllable even under full braking. The driver feels the operation of the anti-lock braking system by the pulsation of the brake pedal and the noise of the ABS hydraulic unit in the engine compartment.
The ABS control unit's shutdown function automatically shuts down the system if a fault occurs, such as a broken power supply wire or if the on-board voltage drops below 10.5 V. ABS shutdown is indicated by the illumination of a warning light on the instrument panel. At the same time, the normal braking system continues to function and the car behaves like a car without ABS.
After the ignition is turned on, the ABS system performs a self-test. After approximately 3 seconds, the indicator light on the instrument panel should go out. If the warning light continues to burn or comes on while driving, do the following:
- 1. Stop, turn off and start the engine again.
- 2. Check the battery voltage. If it is less than 10.5 volts, charge the battery.
- 3. Check that the terminals on the battery terminals are securely fastened.
- 4. Place the car on jack stands and remove the wheels. Check the ABS sensor wires for external damage (grinding). Further ABS testing should be performed in a workshop. The ABS control unit runs a self-diagnostic program and all faults are recorded. These faults can be read in the workshop using a diagnostic tester and then repaired.
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In addition to ABS, the vehicle may be equipped with an electronic stability program (ESP) or a brake force regulator. ESP uses ABS elements and complements ABS, reducing the risk of the car skidding even when the accelerator pedal is not pressed or during braking.
When cornering at high speed or performing abrupt maneuvers, the automatic stability control system recognizes the vehicle's "intention" to lose stability. For this purpose, the ESP control unit takes into account the information from the sensors about the steering angle and, based on the vehicle speed, calculates the angular velocity (rotation speed) the vehicle relative to the vertical axis and instantly determines the moment when the vehicle may lose stability. By regulating the pressure in the brake mechanisms of the corresponding wheels, as well as braking the engine, ESP ensures that the car immediately returns to a position in which its stability is not threatened. If, for example, when driving on a sharp turn there is a risk of skidding of the front wheels of the car, the system deliberately brakes the rear wheel located on the inside line of the turn and thereby stabilizes the car. If there is a risk of rear wheel skidding, the front wheel moving along the outer line of the turn is braked.
Vehicles with ESP are additionally equipped with an electronic traction control system (ASR). This system brakes spinning wheels and transfers torque to the wheels with firm traction. The system monitors the rotation of the wheels and applies the brakes, increasing the pressure in the brake mechanism of the wheel that begins to slip. In this way, the traction force is used to the maximum extent by wheels that have good traction on the ground or road surface.