11.2. System of anti-blocking of brakes (ABS) - the general information and codes of malfunctions
The system of anti-blocking of brakes (ABS) is included in the additional package of the considered models.
When the vehicle is equipped with the brake system of usual type, sharp squeezing of a pedal of a foot brake leads to blocking of wheels. At the same time coupling of a protector with a paving is broken, and the car can start to skid, losing controllability. The system of anti-blocking of brakes (ABS) prevents premature blocking of wheels, continuously operating the speed of their rotation during braking due to modulations of pressure of hydraulic liquid in each of brake mechanisms.
ABS consists of two main subsystems: electric and hydraulic. Four sensors of speed of rotation of wheels, the processor of management and a set of a connecting electrical wiring enter an electric part of system. A hydraulic part includes pressure modulator, supports of disk brake mechanisms and hydraulic lines connecting components.
ABS system components
1 — Forward wheel sensors
4 — the ABS Control unit
The principle of functioning of system is rather simple. Each of wheels is equipped with the individual RPM meter. The sensor consists of a rotor (a ring with the teeth which are evenly located on its perimeter) and a sensitive element in the form of the podmagnichenny coil. The sensitive element of the sensor fixes the moments of passing of rotor teeths by it and will transform the obtained information to electric signals, control of ABS which are continuously transferred on the processor. By results of processing of the arriving signals the processor obtains information on the relative speed of rotation of each of wheels. While all four wheels rotate with an identical frequency, ABS stays in a passive state. As soon as any of wheels begins to be blocked, the processor fixes change of the entering signal and develops the command for operation of the modulator which is instantly dumping pressure of hydraulic liquid in the brake mechanism of the corresponding wheel At once after restoration of normal rotation of a wheel, the processor stops functioning of the modulator.
Principle of functioning of ABS of a brake contour of a parallel configuration
Principle of functioning of ABS of a brake contour of a diagonal configuration
|Brake fluid comes to the accumulator and is pumped over by the returnable pump (RFP) via the damping camera (D) back in GTTs, chtopozvolyat to smooth pressure peaks, reducing thereby a noise background. The control valves which are switched on parallel to the EV valve provide a possibility of bystry pressure decrease at an otpuskaniye of a brake pedal|
V \Forward brake mechanisms
L — the Brake mechanism of the left wheel
For the purpose of prevention of impact on functioning of ABS of false signals, the special contour of safety is built in system of its management. At revenues to the control unit of an inadequate signal, and also at excessive falling of level of supply voltage, the system is automatically disconnected, and on the dashboard the control lamp of ABS lights up (see the Head Governing bodies and methods of operation at the beginning of the Management). The brake system at the same time continues to function in the usual mode.
Actually the scheme of functioning of the ABS system is much more difficult, than it can seem therefore authors of the present manual do not recommend to owners of cars to make attempts of independent performance of repair of system. In case of malfunctions it will be most reasonable to address specialists of car service where the corresponding diagnostics will be made with use of the skanerny reader connected to the DLC socket (see the Head of the Power supply system, release and decrease in toxicity of the fulfilled gases).
Reading of codes of malfunctions of ABS
At start of the engine the control lamp of ABS on an instrument guard of the car has to join quickly and almost at once again go out. If because of any violation the lamp remains included after implementation of start of the engine, the ABS processor writes down the corresponding digital code in memory of the block of self-diagnostics. Reading of codes is made by means of the special scanner connected to the 16-contact diagnostic socket located under a forward overlay of a threshold of a driver's door of the car. In lack near at hand of the scanner the car should be driven away for reading of memory and performance of necessary recovery repair on car repair shop. The ID card of the diagnostic ABS codes is provided in Specifications of the Head the Brake system.
Cleaning of the processor memory of ABS
After elimination debugged system the processor memory it has to be cleared. Memory cleaning requires again the scanner in the absence of which near at hand the car should be driven away on car repair shop. More detailed information on the skanerny reader is provided in the Head Sistemy of electric equipment of the engine.