Start procedure, function

W07.15-1344-79

Shown on engine 906.9

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

A6 MR/PLD control unit

A22 PSM control unit

A42 WSP control unit

B10 Fuel temperature sensor

B15 Crankshaft angle position sensor

B16 Cylinder 1 TDC sensor

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

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

* Only on 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

B65 Coolant temperature sensor

B111 Charge air combination sensor (temperature, pressure)

M1 Starter

S1 Drive switch

S10 Start engine pushbutton switch

S11 Stop engine pushbutton switch

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

Y11 Cylinder 6 unit pump

General

The engine can be started

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

 over the Start engine pressbutton switch (S10),

or,

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

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Requirements

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

 Vehicle immobilizer (WSP) deactivated which means that the MR/PLD control unit (A6) has received the valid transponder code from the control unit WSP (A42) and could therefore recognize the correct ignition key.

 Lock removed from starter function, which means:

 Transmission in neutral when the start command was given via the Start engine pressbutton switch (S10)

 Auxiliary drive, when present, switched off

 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 into position terminal 50 (3) and held there, the Start engine pressbutton switch (S10) pressed or an appropriate message is sent from the PSM control unit (A22), the MR/PLD control unit (A6) actuates the starter solenoid of the starter (M1) over 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 rpm. In addition, the control waits until it has detected the crankshaft angle position sensor (B15) and the cylinder 1 top dead center sensor (B16) the compression cycle of cylinder 1 based on signals 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 terminal 50 (3) of the drive switch (S1) or the Start engine pressbutton 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, actuation of the starter (M1) is interrupted (starter break-off speed). The pinion is withdrawn from toothing on the flywheel while the engine control (MR) shifts into the desired regulating mode.

The increased starting amount required is, of course, increased, as required, by the MR/PLD control unit (A6).

The starting time is limited to 90 s to avoid overloading 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 s 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.