The applied positions of the engine stop pushbutton switch (S10) are read in and evaluated by the MR/PLD control unit. If the engine stop pushbutton switch (S11) is operated, the MR/PLD control unit stops the actuation of the solenoids in the unit pumps, irrespective of whether the engine is running or not. All fuel delivered by the plunger-and-barrel assemblies in the unit pumps between bottom and top dead center is immediately forced into the diversion chamber concerned, then into the fuel return line. Since the ejection pressure of the injection nozzles is not reached, fuel injection does not take place and the engine either stops, or will not start.
This allows the engine to be switched off and also, if the engine start pushbutton switch (S10) is operated at the same time as the engine stop pushbutton switch (S11), to be cranked without starting, when carrying out service-operations.
To prevent the engine being switched off inadvertently, the engine stop pushbutton switch (S11) must be pressed and held until the engine stops. If the engine stop pushbutton switch (S11) is released, the engine will start again if the engine speed is still over 50 rpm.