Slip Control System (ASC)

Slip Control System (ASC)


Traction control is standard equipment on both the 323 and 328 Models. The Teves - Mark 20 EI system is used for the E46. The theory/operation of the slip control system is unchanged from the previous ASC system. The major changes of the Mark 20 EI are:
- The electronic control module is integrated into the hydraulic unit.
- The throttle reduction operation is carried out through the DME's activation of the DK motor.
- The ASC control module communicates with the AGS and DME control modules over the CAN Bus.

The Mark 20 EI system now includes the Cornering Brake Control (CBC) utilized in the Bosch ASC 5 system. This feature reduces pressure build-up on the inside rear brake circuit while cornering, it the threshold values for activation are exceeded.

Electronic Brake Proportioning (EBV)

A new feature of the Mark 20 EI system is the Electronic distribution of the braking force (EBV). This feature will adjust the braking force to the rear wheels based on the vehicle's loading to maximize the braking force at all wheels.

The control module monitors the wheel speed sensor inputs, when the brakes are applied, to determine vehicle loading. The control module compares the rate at which the front and rear axles are slowing down.

If the rear axle is slowing at a rate similar to the front it indicates that the vehicle is loaded and more braking force can be applied to the rear calipers to stop the vehicle.

If the decel rate of the rear wheels is far less than the front, it indicates a lightly loaded vehicle. At this point, if the same braking force were applied to the front and rear axles, the vehicle would become unstable.

If this difference exceeds the threshold values programmed in the control module, EBV is activated. The control module will cycle the inlet valves to the rear brakes to regulate the braking force.

Diagnosis

Diagnosis of the slip control system is carried out with the DIS or MoDiC using the fault symptom driven troubleshooting procedures.