GF42.40-D-0003H Acceleration Slip Regulation (ASR), Function

GF42.40-D-0003H Acceleration Slip Regulation (ASR), Function


The Acceleration slip regulation (ASR) lastingly improves the traction and assists starting off and accelerating particularly on a smooth road. In order to prevent the drive wheels from spinning, the ASR can brake individual wheels and limit the torque of the engine. With snow chain operation, in deep snow or sand or gravel it can be an advantage to switch off ASR so that the engine torque is not limited. As a result the drive wheels are allowed to spin in order to achieve a type of milling effect for better traction. Switching off (ASR OFF function) is therefore possible via the ASR OFF button (N72/1s5)Traction control via one-sided interventions by the brake system however continues to be permitted, if one wheel, e.g. on slippery roads, achieves the adhesion limit. This wheel is then also braked when ASR is switched off in order to increase the traction potential.

The ASR OFF function is deactivated by pressing the ASR OFF button again or when detecting an unstable driving condition. The drive torque reduction is controlled by the data exchange between the ESP control unit (N30/4) and the CDI control unit (N3/20), with OM 642, or CDI control unit (N3/21), with OM 646, or the ME-SFI [ME] control unit (N3/23), with M 272, via the Controller Area Network-Bus Class C (engine compartment) (CAN-C). By the CDI control unit (N3/20), with OM 642, or CDI control unit (N3/21), with OM 646, or the ME-SFI [ME] control unit (N3/23), with M 272, the engine torque is reduced compared with the value specified by the driver via the accelerator pedal module (B37/3).

In the ESP control unit it is constantly checked whether the control functions can be canceled, for example as a result of a road surface which has suddenly improved in order to permit again as soon as possible the drive torque specified by the driver via the accelerator pedal module.