Anti-lock braking system (ABS) (BMW 5 Series E39)

The ABS system increases the active safety of the car by preventing the wheels from locking when braking. After all, wheel locking is extremely dangerous, since the front wheels become uncontrollable, and the skidding rear wheels can cause the car to skid and be thrown onto the other side of the road.

The ABS system allows in any specific conditions (when driving straight, on a turn, on an asphalt, icy or wet road, etc.) reduce the braking distance to a minimum.

In principle, with each braking, ABS must solve two problems, ensuring trajectory stability on roads with different types of surfaces (asphalt, concrete) and in different states (icy, muddy, snowy or wet roads) reliable controllability and maneuverability of the vehicle under the above conditions.

These requirements require substantial commentary.

ABS does not cancel out the laws of physics. The system cannot prevent the consequences of braking at insufficient distance from the vehicle in front, cornering at an unacceptably high speed or when there is a risk of aquaplaning. These consequences still remain on the driver's conscience. The presence of ABS, which provides increased safety potential, should not provoke you to excessively risky driving.

Features of driving a car with ABS

After starting the engine, the ABS warning light on the instrument panel goes out.

The system is automatically activated only when the speed reaches about 8 km/h. When it falls below 3 km/h, ABS is switched off, so theoretically the wheels can lock at the very last stage of braking, but in practice this is no longer of fundamental importance.



ABS implements the regulation process in a fraction of a second. Pulsing of the pedal under the foot means that braking is under the control of ABS, in other words, that the driver is driving in the limit mode. In addition, the crackling caused by the ABS operation process reminds the driver of the need to adjust the speed to the actual driving conditions that have changed due to the reduction (for example, due to icy conditions) coefficient of friction (or clutches) between the tires and the road.

On roads with a loose layer (for example, gravel or snow) over a base with good grip properties, the braking distance may be longer than when the wheels are locked. This also applies to driving with anti-skid chains. Much more important, however, is the gain in trajectory stability and control of the car.

To maintain the full functionality of the ABS, do not make any modifications to it. Work on the system should only be performed by authorized specialists.

Driving on different tires, for example after installing a spare tire (in combination with the other three wheels, on which winter tires are mounted) may limit the functionality of the ABS. Therefore, the removed wheel should be reinstalled as soon as possible. A malfunction signal is the ABS warning light on the instrument panel (refer to Section 1). In this case, the brake system continues to operate normally, as in cars without ABS. However, contact a BMW service station as soon as possible to check the brake system. Otherwise, it may develop faults that are difficult to detect.

Power steering

If the steering is difficult to operate, check the oil level as recommended in Chapter 1.

If difficulties arise when trying to quickly turn the steering wheel, then you should definitely contact a BMW service station for inspection.

When the power steering fails, the effort required to turn the steering wheel increases.