ABS prevents the wheels from locking during heavy braking. As a result, with full braking, the car remains steerable.
ABS works as soon as the ignition is on and the speed is 5-7 km/h. It regulates all braking processes in the blocking area as soon as the speed exceeds 12 km/h.
Thanks to the speed sensors, two for the front and rear wheels, the speed of rotation of the wheel is measured. By analyzing the signals from the individual speed sensors, the electronic control unit calculates an average speed that corresponds approximately to the average speed of the machine. By comparing the rotational speed of an individual wheel and the average rotational speed of all wheels, the control unit recognizes the slip state of the individual wheel and can thereby detect the wheel condition shortly before it locks up.
The possibility of blocking the wheel means that the pressure of the brake fluid in the corresponding brake mechanism is too high in relation to the adhesion of the wheel to the road, in this case the hydraulic system, receiving signals from the control unit, maintains the fluid pressure constant. Namely, the pressure in the brake mechanism does not rise even if you press the brake pedal harder. If the possibility of blocking is maintained, then the fluid pressure is reduced when the exhaust valve is opened, but only enough so that the wheel accelerates slightly, then the pressure is again held constant.
If the wheel accelerates more than a certain value, then the pressure of the hydraulic system increases again, but not above the value of the total brake pressure.
This operation is repeated with hard braking for each individual wheel until the brake pedal returns to its original position or shortly before the machine comes to a complete stop.
A safety device in the electronic control unit ensures that the ABS, in the event of a malfunction, (such as an open circuit) or too low voltage of the on-board network (battery voltage less than 10.5V) switched itself off. In this case, the ABS warning light on the instrument panel lights up while driving. The conventional braking system remains operational. The car behaves when braking as if ABS is not installed.
If the ABS warning light comes on while driving, this is a signal that the ABS system has been deactivated. In this case, you should:
- stop the car for a while, turn off the engine and start again;
- check battery voltage;
- if the voltage is below 10.5V, charge the battery.
Attention! If the ABS warning light comes on when you start driving and goes out again after a while, this indicates that the battery voltage was too low at first, but then rose as a result of recharging from the generator.
Examination
1. Check the tightness and good contact of the battery terminals.
2. Place the machine on a trestle, remove the front wheels, check the electrical wiring of the speed sensors for external damage.
3. Further check to be carried out at the service station.
Attention! Before welding with an electric welding device, disconnect the plug from the electronic control unit (Installation location: Behind the driver's door pillar trim. Disconnect the plug only when the ignition is switched off, do not start driving with the plug disconnected. When painting and varnishing work, it is allowed to expose the control unit to short-term temperatures up to + 90°C and long-term (about 2 hours) up to + 85°С.
Visitor comments