Switching off procedure - function

W07.15-1282-79

Shown on engine 541.9

0 Ignition OFF

1 C. 15R ON

2 Circuit 15 ON

3 Kl.50

4 Engine CAN bus

5 Vehicle CAN bus

A3 Drive control (FR) control unit

A5 GGVS control unit

A6 MR/PLN control unit

A7 Base module

A22 PSM control unit

Y9 Cylinder 4 unit pump

Y10 Cylinder 5 unit pump

Y11 Cylinder 6 unit pump

Z1 CAN star point cab dash support

* Engine 541.9 up to engine end no. 106266 and engine 542.9 up to engine end no. 109389

** Engine 541.9 as of engine end no. 106267 and engine 542.9 as of engine end no. 109390

B15 Crankshaft angle position sensor

K2 Battery disconnect switch

S1 Drive switch

S5 Cab EMERGENCY OFF switch

S10.1 Pushbutton, engine start/stop

S11 Engine stop pushbutton switch

S109 Right frame EMERGENCY OFF switch

Y1 Engine brake solenoid valve 1

Y6 Cylinder 1 unit pump

Y7 Cylinder 2 unit pump

Y8 Cylinder 3 unit pump

The engine can be stopped:

 with the ignition key over the drive switch (S1)

 with the pushbutton switch Start engine (S11) or with the pushbutton switch Start engine/Stop engine (S10.1)

 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, over the PSM control unit (A22)

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 for vehicle operating according to the German hazardous goods road transport regulations with the Emergency Stop switch in the cab (S5) or with the Emergency Stop switch on the frame on the right (S109)

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1 Stopping the engine with the ignition key over the drive switch (S1)
After rotating the ignition key into position ignition OFF (0), the voltage supply (circuit 15) to the MR/PLN control unit(A6) is interrupted over the driving switch (S1).
Interruption of the voltage supply (circuit 15) means that the solenoid valves in the unit pumps will no longer be actuated. The total quantity of fuel which the plunger-and-barrel assembly in the unit pumps delivers between bottom and top dead center will first be pushed into the respective diversion chamber and then into the return flow duct. The fact that the ejection or opening pressure on the injection nozzles is no longer achieved means that there is no further fuel injection and the engine stops.
The constant throttle valves in the cylinder heads are actuated simultaneously in order to accelerate the stop process and to protect the engine and the environment.

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The fact that the solenoid valve on engine brake 1 (Y1) which leads compressed air to the constant throttle valves in the cylinder heads is connected to the drive control (FR) control unit (A3) means that the engine control (MR) requests actuation of the solenoid valve through transmitting appropriate messages over the
vehicle CAN bus (5).

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

The MR/PLN control unit (A6) will still be supplied with power for at least 10 seconds from circuit 30 after the engine stop process. This period, the so-called run-on phase, is used to write to the permanent diagnostic fault code memory.

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2 Stopping the engine using the pushbutton switch Start engine (S11) or the pushbutton switch Start engine/Stop engine (S10.1)

The pushbutton switch Stop engine (S11) or the stop switch on the pushbutton switch Start engine/Stop engine (S10.1) must remain pressed until the engine stops to prevent inadvertent stopping of the engine. If the pushbutton switch Stop engine (S11) or the stop switch on the pushbutton switch Start engine/Stop engine (S10.1) is released before the engine speed is below 50 rpm, the engine will start again.

Actuation of the pushbutton switch Stop engine (S11) or the stop switch on the pushbutton switch Start engine/Stop engine (S10.1) causes the MR/PLN control unit (A6) to interrupt actuation of solenoid valves in the unit pumps.

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The unit pumps deliver the fuel, as with the Stop procedure using the ignition key, directly into the return line, whereby injection is interrupted and the engine stops as soon as the engine speed drops below 50 rpm.
If the engine is stationary the MR/PLN control unit (A6) sends an appropriate message over the engine CAN bus (4) concerning the stationary 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 order for it to be able to include this information in its further calculations.

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3 Stopping the engine over 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 over the vehicle CAN bus (5) with the drive control (FR) control unit (A3). If it transmits an appropriate message to stop the engine then this will be passed on by the drive control (FR) control unit (A3) over the engine CAN bus (4) to the MR/PLN control unit (A6).

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The MR/PLN control unit (A6) interrupts actuation of the solenoid valves in the unit pumps which causes the engine to stop.
The constant throttle valves in the cylinder heads will also be actuated in the same way as stopping the engine over the parameterizable special module control unit (A22) and in the same way as stopping the engine using the ignition key.
The MR/PLN control unit (A6) goes into the run-on phase in order to write to the permanent diagnostic fault code memory.

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4 Stopping the engine using the Emergency Stop switch in the cab (S5) or the Emergency Stop switch on the frame on the right (S109)

 Only for vehicles operating according to the German hazardous goods road transport regulations.

The Emergency Stop switch in the cab (S5) and the Emergency Stop switch on the frame on the right (S109) are connected up (in series) to the German hazardous goods road transport regulations operations 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 German hazardous goods road transport regulations operations control unit (A5) immediately interrupts the voltage supply (circuit 30) to all consumers except the modular tachograph (MTCO) or the flat tachograph (FTCO) by actuating the battery disconnect switch (K2), .

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

 The Emergency Stop switch should only be used in cases of danger and on a stationary vehicle and never when driving since the vehicle will no longer be controllable.