ABS/ASR General System Description

The acceleration slip control (ASR) system works automatically to improve standing starts and acceleration, as well as handling.

The version II of the ASR system has various improvements over the previous system, which was introduced to the European market earlier. All descriptions refer exclusively to the ASR II system.

SYSTEM DESCRIPTION
ASR is a further logical development and compliments the antilock brake system (ABS). ABS prevents wheel lockup during braking, and thus the vehicle retains steering control and handling. ASR prevents drive wheel spin caused by acceleration, resulting in better use of the available traction. For ASR, the basic components of ABS are supplemented by a hydraulic unit with expanded functions, a charging pump, a hydraulic pressure reservoir, a fourth wheel speed sensor, a more comprehensive electronic system and the electronic accelerator system with its control unit, reference potentiometers and actuator.

In addition, the electronic accelerator control unit controls the cruise control system.


ADVANTAGES:

^ Increased use of available traction improves standing start and acceleration capacity: this is particularly advantageous on road surfaces with variable friction and in turns.
^ The system increases active dynamic safety, since only a wheel that is not spinning can attain optimal traction without loss of lateral control.
^ If the driver depresses the accelerator pedal too far, the system automatically reduces engine torque to the capacity of the wheels to transmit torque to the road at that moment.
^ Through the ASR control system, a function indicator lamp informs the driver that the vehicle has approached the limits of tire adhesion.