Operating principle
The ABS system improves the vehicle's active safety by preventing the wheels from locking when braking. After all, blocking the wheels is extremely dangerous, since the front wheels become uncontrollable, and the rear wheels going skidding can lead to the car skidding and ejection to the other side of the movement.
The ABS system allows in any specific conditions (when driving in a straight line, on a bend, on an asphalt icy or sea road, etc.) reduce braking distance to a minimum. In principle, with each braking, the ABS must solve two problems, providing trajectory stability, reliable handling and maneuverability of the car when driving on roads of different types of coverage (asphalt, concrete) and in different states (icy, covered with mud, snow, water).
Features of driving with ABS
The system is automatically activated only after reaching a speed of about 10 km/h. When it falls below 6 km / h, ABS is turned off, so theoretically at the very last stage of braking the wheels can lock up, but in practice this is no longer of fundamental importance.
The benefits of ABS are most pronounced in situations where you have to apply maximum force to the brake pedal. Since the vehicle's front wheels remain steerable, you can safely drive around obstacles.
ABS implements the regulation process in a fraction of a second. Pulsation of the pedal under the foot means that braking is under ABS control, in other words, that the driver is driving in the limit mode. In addition, the crackling noise caused by the ABS operation reminds the driver to adjust the speed to the actual driving conditions that have changed due to the reduction in (for example, due to ice) friction coefficient (or clutch) between tires and road.
On loose roads (e.g. rubble or snow) over a base with good traction, the braking distance may be longer than when the wheels are blocked. The same applies to driving with snow chains. Much more important, however, is the gain in trajectory stability and vehicle handling.
Important information for your safety
ABS does not override the laws of physics. The system cannot prevent the consequences of braking when there is insufficient distance from the vehicle in front, when cornering at unacceptably high speeds, or when there is a risk of aquaplaning. These consequences still remain on the conscience of the driver. The presence of ABS, which provides increased safety potential, should not provoke you to an unnecessarily risky driving style.
Driving on dissimilar tyres, e.g. after fitting a spare wheel (in combination with the other three wheels, on which tires with a winter tread pattern are mounted) may limit the functionality of the ABS. Therefore, the removed wheel must be reinstalled as soon as possible.
Do not make any changes to the system.
Work on the system must only be carried out by specialists.
Anti-Lock Braking System (ABS) / Cornering Brake Control (SHS)
The CBC system is an advanced version of ABS. Under braking conditions in corners with high lateral acceleration, as well as when braking during lane changes, the system improves driving stability and controllability.
In the event of a malfunction
The malfunction signal is the inclusion of the ABS warning light. In this case, the brake system continues to operate normally, as on vehicles without ABS. Refer to Section Troubleshooting.
If the lamp lights up together with the control lamps of the ABS and ASC + T / DSC * systems, then this indicates the failure of the entire complex of the ABS, CBC and ASC + T / DSC control systems. You can continue to drive with the necessary precautions, as the vehicle may become unstable and out of your control.
Refer to Section Troubleshooting and go to a BMW workshop to have the system checked as soon as possible.