Start procedure, function

W07.15-1328-79

0 Ignition OFF

1 Circuit 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/PLD control unit

A22 PSM control unit*

A42 WSP control unit

B10 Fuel temperature sensor

Y9 Cylinder 4 unit pump

Y10 Cylinder 5 unit pump

Y11 Cylinder 6 unit pump

Z1 CAN star point cab dash support

* Only on vehicles with code (EM7) Parameterizable special module with body CAN bus or code (EM8) Parameterizable special module with body and trailer CAN bus

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

S11 Engine stop pushbutton switch

Y6 Cylinder 1 unit pump

Y7 Cylinder 2 unit pump

Y8 Cylinder 3 unit pump

General

The engine can be started

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

 with the engine start pushbutton switch (S10),

or,

 by means of the PSM control unit (A22) in the case of vehicles with code (EM7) Parameterizable special module with body CAN bus or code (EM8) Parameterizable special module with body and trailer CAN bus

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Requirements

 Voltage supply (Tml. 30 and Tml. 15) available at MR/PLD control unit (A6).

 Immobilizer (WSP) deactivated, i.e. the MR/PLD control unit (A6) has received the valid transponder code from the WSP control unit (A42) and has therefore detected the correct ignition key.

 Lock removed from the starter function, which means:

 transmission in neutral in the case of start command via the engine start pushbutton switch (S10)

 PTO (if fitted) deactivated

 engine stopped or the engine speed is <50 rpm

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Function

If all conditions are fulfilled and the ignition key is turned to position Tml. 50 (3) and held there, the engine start pushbutton switch (S10) pressed or an appropriate start-command message is sent from the PSM control unit (A22), then the MR/PLD control unit (A6) actuates the starter solenoid on the starter (M1) via a series 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 r.p.m. In addition, the control waits until it has detected the compression stroke of cylinder 1 by means of the signals from the crankshaft angle position sensor (B15) and from the cylinder 1 TDC sensor (B16) so that it can then calculate the start of delivery (to control the start of injection).

The required fuel injection amount is also being calculated at the same time according to the current operating condition of the engine and is controlled through appropriate actuation of the solenoid valves in the unit pumps.

If the engine starts while the ignition key is held in position Tml. 50 (3) of the drive switch (S1) or the engine start pushbutton switch (S10) is still being pressed and the engine reaches a speed of approx. 450 rpm for a warm engine or approx. 650 rpm for a cold engine, then actuation of the starter (M1) is interrupted (starter break-off speed). The pinion is withdrawn from the toothing on the flywheel while the engine control (MR) shifts into the desired regulating mode.

The excess fuel input which may be required is of course increased, as required, by the MR/PLD control unit (A6).

The starting time is limited to 90 seconds to avoid overloading of the starter (M1) for extremely low outside temperatures which leads to poorer starting behavior. Actuation of the starter (M1) and the solenoid valves in the unit pumps is interrupted. It is then only after a short waiting time (at the earliest 1 second after switching off the starter) that a new start procedure can be begun from the beginning. The start time can, however, be made significantly shorter for vehicles with code (M89) Flame starting system.