MDK

The MDK control function is integrated into the Siemens MS42.0 ECM. The ECM carries this function out by regulating the engine throttle valve.

The engine throttle valve performs the following functions:
- Precision intake air control
- ASC control
- MSR control
- Cruise control
- Preset position during engine start up (if temperature is < 0°)

The new engine throttle valve (MDK) differs from the familiar EML in the following points:
- The accelerator pedal potentiometer (PWG) is now integrated in the MDK housing.
- A throttle cable is used to actuate the throttle potentiometers and also serves as a backup to open the throttle plate (full control) if the MDK system is in failsafe.







The throttle cable (toot pedal controlled) is connected to a pulley on the side of the MDK/ The pulley is linked by springs to one end of the throttle shaft, the MDK electric motor is attached to the other end of the throttle shaft.

With the pulley linked by springs to the throttle shaft, this allows ASC intervention to override the driver's set throttle position.

As the pulley and shaft are rotated, the twin potentiometers (integral in the MDK housing, driver's wish) are sensing the requested load. A twin potentiometer is used for back up redundancy (failsafe).

The MS42.0 ECM will actuate the MDK motor pulse width modulated in both directions at a basic frequency of 600 Hz) which positions the throttle plate.

The second twin potentiometers feedback the actual throttle plate position, allowing the ECM to verify correct throttle position. Again, twin potentiometers are used for back up redundancy (failsafe).