Starting procedure function

W07.15-1275-79

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

A6 MR/PLN control unit

A22 PSM control unit
- 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

A42 WSP control unit

Y8 Cylinder 3 unit pump

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

B10 Fuel temperature sensor
- Only on engine 541.9
up to engine end no. 094097
and engine 542.9
up to engine end no. 094246

B11 Oil temperature sensor

B15 Crankshaft angle position sensor

B16 Cylinder 1 TDC sensor

B65 Coolant temperature sensor

B111 Charge air combination sensor (temperature, pressure)

M1 Starter

S1 Drive switch

S10 Engine start pushbutton switch

S10.1 Pushbutton, engine start/stop

S11 Engine stop pushbutton switch

Y6 Cylinder 1 unit pump

Y7 Cylinder 2 unit pump

General

The engine can be started

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

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

or,

 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)

Requirements

 Voltage supply (circuit 30 and circuit 15) applied to MR/PLN control unit (A6).

 Immobilizer (immobilizer (with transponder)) disarmed which means that the MR/PLN control unit (A6) has received the valid transponder code and thus recognized the correct ignition key from the immobilizer (with transponder) control unit (A42).

 Lock on starter operation lifted, which means:

 Transmission in neutral for start command over the pushbutton switch Start engine (S10)

 Power take-off, where installed, switched off

 Engine stationary or engine speed <50 rpm

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Function

If all requirements are complied with and if the ignition key is turned into position circuit 50 (3) and held there, the pushbutton switch Start engine (S10) or the starter switch on the pushbutton switch Engine start/Engine stop (S10.1) is actuated or an appropriate message is sent from the PSM control unit (A22), then the MR/PLN control unit (A6) actuates the starter solenoid on the starter (M1) over a front-end relay.

The starter (M1) sets the engine in motion and the engine control (MR) checks whether the starter (M1) is turning the engine at a minimum speed of 50 rpm. It also waits until it has recognized the compression stroke of the 1st cylinder based on signals from the crankshaft angle position sensor (B15) and the TDC sensor on cylinder 1 (B16) in order then to be able calculate the start of delivery (to regulate the start of injection).

The required injection quantity for combustion is calculated according to the current operating condition of the engine and controlled at the same time through appropriate actuation of solenoid valves in the unit pumps.

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If the engine starts while the ignition key is held in position circuit 50 (3) of the drive switch (S1) or the pushbutton switch Engine start (S10) or the starter switch on the pushbutton switch Engine start/Engine stop (S10.1) is still actuated and it reaches a rotational speed of about 450 rpm for a warm engine up to about 650 rpm for a cold engine, then actuation of the starter (M1) will be interrupted (starter cut-off speed). The pinion is withdrawn from the toothing on the flywheel while the engine control (MR) switches over into the desired closed-loop operation.

The possibly required excess fuel input will be increased autonomously as required by the MR/PLN control unit (A6).

If the outside temperature is particularly low and there are therefore poor starting characteristics, the start time will be limited to 40 seconds to avoid overloading the starter (M1). Actuation of the starter (M1) and the solenoid valves in the unit pumps will be interrupted. The starting procedure can only be restarted afresh after a certain waiting time (at the earliest 1 second after switching off the starter) . The start time can be shortened significantly, however, on vehicles with code (M89) Flame starting system.