Engine shutoff procedure, function

W07.15-1349-79

0 Ignition OFF

1 Circuit 15R ON

2 Circuit 15 ON

3 Circuit. 50

4 Engine CAN bus

5 Vehicle CAN bus

A3 Vehicle engine control (FMR) control unit

A5 GGVS** control unit

A6 MR/PLD control unit

A7 Base module

A22 PSM control unit

B15 Crankshaft angle position sensor

B16 Cylinder 1 TDC sensor

K2 Battery disconnect switch**

S1 Drive switch

S5 Cab EMERGENCY OFF switch

Z1.1 CAN star point cab dash support
Model 375.1, 970, 972, 974, 975, 976

* Vehicles with
code (ED5) Parameterizable special model (PSM),
code (EM7) Parameterizable special model with body CAN bus or code
(EM8) Parameterizable special
module with body and trailer CAN bus

** Vehicles in accordance with the German hazardous goods road transport regulations

S10 Start engine pushbutton switch

S11 Stop engine pushbutton switch

S109 Right frame EMERGENCY OFF switch

Y1 Solenoid valve exhaust brake 1

Y6 Cylinder 1 unit pump

Y7 Cylinder 2 unit pump

Y8 Cylinder 3 unit pump

Y9 Cylinder 4 unit pump

Y10 Cylinder 5 unit pump
- Only for engine 906.9 and 926.9

Y11 Cylinder 6 unit pump
- Only for engine 906.9 and 926.9

Y49 Constant throttle solenoid valve

Z1 CAN star point cab dash support
Model 375.3, 950, 952, 953, 954

The engine can be stopped:

 over the drive switch (S1) by using the ignition key,

 over the Stop engine pressbutton switch (S11)

 for vehicles with code () Parameterizable special module (PSM), EM7 code (EM8) Parameterizable special module with body CAN bus or code (A22) Parameterizable special module (PSM) control unit (ED5)

 for vehicles according to GGVS, by using the EMERGENCY-STOP button in the cab (S5) or the EMERGENCY-STOP button (S109) on the right vehicle frame

1 Switching off of engine with ignition key on drive switch (S1)

After turning the ignition key to the ignition OFF position (0), the power supply (circuit 15) on the MR/PLD control unit (A6) is interrupted by the drive switch (S1) .
Interruption of the voltage supply (terminal 15) means that the solenoid valves in the unit pumps will no longer be actuated. The total volume of fuel which the pump elements deliver between bottom dead center and top dead center is initially pushed into the respective diversion chamber and then into the return channel. The ejection pressure or the opening pressure of the injection nozzles is no longer achieved so there is no further fuel injection and the engine stops.

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 The constant throttle in the cylinder heads is also actuated at the same time to accelerate the engine stopping process and to be more gentle on both the engine and the environment. The fact that there are both hydraulically and pneumatically actuated constant throttle valves depending in the engine, means that actuation of the respective solenoid valve occurs (for controlling the constant throttle) either by the MR/PLD control unit (A6) or the drive control (FR) control unit (A3).

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 Vehicles with hydraulically actuated constant throttle valves (applies to vehicles with engine 906.9 and 926.9):
These constant throttle valves are controlled by the hydraulic constant throttle solenoid valve (Y49) which is actuated by the MR/PLD control unit (A6).

 Vehicles with pneumatically actuated constant throttle valves (applies to vehicles with engine 904.9):
In this case, the engine control (MR) requests to the drive control (FR) to actuate the pneumatic constant throttle solenoid valve 1 (Y1) since compressed air is supplied to the constant throttle valves via this solenoid valve. The MR/PLD control unit (A6) sends an appropriate message for this purpose via the engine CAN bus (4) to the drive control (FR) control unit (A3) which then actuates the solenoid valve on the constant throttle 1 (Y1) while the command exists.

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 The period of time in which the engine brake 1 solenoid valve (Y1) is actuated is determined by the engine control (MR).

The MR/PLD control unit (A6) is supplied with power from terminal 30 for at least 10 s after the shut-off process has finished. This period, the so-called run-on phase, is used to write information to the permanent fault memory.

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2 Stopping the engine using the Stop engine pressbutton switch (S11)

 The Stop engine pressbutton switch (S11) must continue to be pressed until the engine has stopped in order to prevent unintentional shutdown of the engine. If the Stop engine pressbutton switch (S11) is released before the engine speed has fallen below 50 rpm, the engine will start up again.

As soon as the Stop engine pressbutton switch (S11) is pressed, the MR/PLD control unit (A6) interrupts actuation of the solenoid valves in the unit pumps.
The unit pumps pump the fuel which flows directly into the return line, as in the case of shutting down the engine using the ignition key, whereby fuel injection is stopped and the engine as soon as the engine speed falls below 50 rpm.

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Once the engine has stopped, the MR/PLD control unit (A6) sends an appropriate message via the engine CAN bus (4) concerning the stationary condition of the engine to the drive control (FR) control unit (A3). This is because the drive control (FR) must be informed about the status of the engine in to be able to take this into account for its further calculations.

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3 Stopping the engine via the PSM control unit (A22)

 Only for vehicles with code (ED5) Parameterizable special module (PSM), code (EM7) Parameterizable special module with body CAN bus or code (EM8) Parameterizable special module with body and trailer CAN bus.

The PSM control unit (A22) is networked via the vehicle CAN bus (5) with the drive control (FR) control unit (A3). If it sends an appropriate message concerning shutdown of the engine, then this will be passed on by the drive control (FR) control unit (A3) via the engine CAN bus (4) to the MR/PLD control unit (A6).
The MR/PLD control unit (A6) interrupts actuation of the solenoid valves in the unit pumps which causes the engine to stop.

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The constant throttle valves in the cylinder heads are also actuated when the engine is shut off via the PSM control unit (A22) in the same manner as when the engine is shut off with the ignition key.
The MR/PLD control unit (A6) goes into the run-on phase in order to write information to the permanent fault memory.

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4 Switching off the engine using the EMERGENCY-STOP button in the cab (S5) or by using the EMERGENCY-STOP button on the right vehicle frame (S109)

 Only for vehicles according to GGVS.

The EMERGENCY OFF switch in the cab (S5) and the EMERGENCY OFF switch on the right vehicle frame (S109) are attached (in series) to the GGVS control unit (A5).
If the ignition key is in the position circuit 15R ON (1) or in the position circuit 15 ON (2), and if one of the two switches is actuated the GGVS control unit (A5) immediately interrupts the power supply (circuit 30) to all consumers except the tachograph through actuation of the battery disconnect switch (K2).

Interruption of the voltage supply (terminal 30) means that the solenoid valves in the unit pumps will no longer be actuated and the engine will stop.

 The EMERGENCY-STOP button must only be actuated in cases of danger and when the vehicle is stationary, but never when the vehicle is moving, otherwise it will no longer be controllable.