ASC interface (Automatic Stability Control)

A choke with actuator motor and an ADS control unit (independent throttle control) are also installed on vehicles equipped with ASC.

Functions

ASC/MSR control (engine drag torque control) is realised by way of following functions:

The DME control unit processes the incoming information from the ABS-/ASC control unit. It performs the tasks of blanking out the ignition (ZA) and interrupting fuel injection and drives the idle actuator as well as the control motor of the automatic throttle actuator in conjunction with the ADS control unit.
The idle actuator opens specifically when the engine drag torque control is activated. It receives its pulse width-modulated signal directly from the DME control unit.
The ADS control unit activates the throttle actuator motor.It is linked by means of a cable assembly with the choke and reduces the engine speed as required. The choke is an additional throttle which is connected upstream of the central throttle. It is opened under spring load (normal status) and is closed by the throttle actuator during ASC control.

ABS/ASC interface

The following ACD-DME interface is required for activation of the necessary ASC functions within the DME M3.3 or for evaluation of the engine speed:

Description	DME control unit	ABS/ASC control unit
Ignition timing adjustment	Pin 82	Pin 77
Ignition mask out	Pin 83	Pin 81
Idle speed increase (anti-stall)	Pin 62	Pin 18
Engine speed signal	Pin 20	Pin 47
Actual throttle value	Pin 11	Pin 20

Based on the extent of slip, the DME control unit receives information from the ABS/ASC control unit.The ABS/ASC control unit determines the control or control combinations to be carried out by the DME control unit.The maximum time the signal inputs are applied at the interfaces is less than 2 seconds.If one or several inputs is applied longer than 2 seconds, a defect code is stored in the defect code memory and the ASC is deactivated.

Masking out ignition and fuel injection (ZA)

The ZA function for DME M3.3 corresponds to the function as already implemented within the DME M1.1, M1.2 and 1.7 for M30 and M70 engines.

If the idle speed increase (anti-stall function) and ignition mask out are activated simultaneously, in addition to throttle adjustment, the ignition is masked out and fuel injection interrupted.Ignition mask-out takes place for maximum 2 seconds.

Ignition timing adjustment (ZWV)

In the same way as the function in DME M1.7, the ignition timing is retarded when ASC is activated.

Idle speed increase (anti-stall) (LDA)

On the basis of the opening of the idle actuator, the MSR function (engine drag torque control) is implemented via the DME when the vehicle is coasting.When the signal is applied, the idle actuator is opened further in order to reduce the drag torque of the engine and to prevent the rear wheels skidding.In addition, the DME cancels the deceleration fuel cutout so that the engine does not stall.

When a vehicle with ASC reaches the control range, the ABS/ASC control unit sends corresponding signals to the DME control unit (see ASC functions). In addition to ignition timing adjustment or ignition mask-out of the DME control unit, the ADS control unit can close the choke in order to reduce the engine speed. In order to be able to decide the extent of the necessary choke adjustment, the ADS control unit receives the actual throttle value of the DME throttle. With the aid of the ADS actuator motor, if necessary, the throttle may be adjusted against the wishes of the driver (accelerator pedal).