Engine control (MR) function

W07.15-1450-79

Overall network, 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

A4 Flame starting system control unit

A6 MR/PLD control unit

A16 GS/EPS control unit

B60 Gear sensor (SGG)

B61 Gate sensor (SGE)

B65 Coolant temperature sensor

B111 Charge air combination sensor (temperature, pressure)

CAN 5 Transmission CAN

K57 Allison neutral relay

M1 Starter

P2 Instrument

P4 Instrument cluster 2000

R3 Flame glow plug

A22 PSM control unit

A42 WSP control unit

A49 Allison automatic transmission control unit

A92 Automatic gear control (AGS) hydraulic controller unit

B1 Foot throttle actuator

B10 Fuel temperature sensor

B15 Crankshaft angle position sensor

B16 Cylinder 1 TDC sensor

S1 Drive switch

S2 Engine control/permanent brake operating lever

S7 Reverse gear switch

S9 Neutral position switch

S10 Start engine pushbutton switch

S11 Stop engine pushbutton switch

S23 PTO 1 indicator switch

S64 PTO 1 switch

S65 PTO 2 switch

S66 Power take-off 3 switch

Y47 PTO 2 solenoid valve

Y48 PTO 3 solenoid valve

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

Z2 Additional cab dash support CAN star point

S79 PTO 2 indicator switch

S80 PTO 3 indicator switch

S108 Switch, ADR

Y5 Flame starting system solenoid valve

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

Y46 PTO 1 solenoid valve

Involved systems

a) Engine control (MR)

b) Flame starting system (FLA)
- Only on vehicles with code (M89) Flame starting system

c) Drive control (FR)

d) Instrument (INS)
- up to 31.12.1999

e) Instrument (INS)
- As of 01.01.2000

g) Automatic gear control (AGS)
- Only on vehicles with code (GE1) Automatic gear control (AGS)

h) Automatic transmission
- Only on models fitted with automatic transmission

i) Gear control (GS)
- Only on vehicles with code (GS2) Gear control

* Only with vehicles with code (GS1) "Manual" gearshift or code (GS3) "Hydraulic" gearshift

** Only on vehicles with corresponding PTO's

f) Parameterizable special module (PSM)
- 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

General information

The engine control (MR) is an independent, electronic system whose main task is to regulate or control the fuel injection function of the pump-line-nozzle system (PLD system). It ensures that the engine is always running in the most fuel efficient, low pollutant and low noise emission manner possible under all operating conditions.

Function

The central control and regulator unit of the engine control (MR) is the MR/PLD control unit (A6). Depending on the operating state of the engine and torque specification by the drive control (FR) control unit (A3), it calculates the optimum start of injection as well as the required injection quantity and ensures that the fuel is injected at the correct time and in the correct quantity into the cylinder by exact electrical actuation of the solenoid valves in the unit pumps.

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The operating condition of the engine is determined based on input values from the following sensors:

 Fuel temperature sensor (B10)

 Crankshaft angle position sensor (B15)

 TDC sensor cylinder 1 (B16)

 Coolant temperature sensor (B65)

 Charge air combination sensor (temperature, pressure) (B111)

While the values relevant for the fuel consumption, output and exhaust are sensed by the charge air combination sensor (temperature, pressure) (B111), the coolant temperature sensor (B65) and the fuel temperature sensor (B10), the MR/PLD control unit (A6) recognizes the momentary speed as well as the rotation angle in relation to TDC (engine position) and in connection with the TDC sensor cylinder 1 (B16), the compression stroke for cylinder 1 over the crankshaft angle position sensor (B15).

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The torque setting, calculated by the drive control (FR) control unit (A3) from the position of the foot throttle actuator (B1), among others, is transferred via the engine CAN bus (4) to the MR/PLD control unit (A6), which itself sends the present actual torque and the maximum possible torque to the drive control (FR).

It is also possible to exchange information with other electronic systems, such as with the instrument (INS) and the parameterizable special module (PSM) via the engine CAN bus (4).

In this manner, the MR/PLD control unit (A6) transfers engine-specific data such as the oil pressure, oil temperature, oil level and speed via the engine CAN bus (4) to the drive control (FR) control unit (A3), which itself transfers this, via the vehicle CAN bus (5), to the instrument (P2) or instrument cluster 2000 (P4) for display.

If a malfunction occurs in the engine CAN bus (4) or in a system component, the engine control (MR) proceeds according to a precisely defined method, depending on the severity of the malfunction. Thus it will fall back on replacement values for less severe faults such as failure of a sensor while it will go into emergency mode for severe faults such as failure of the CAN connection.

The driver is able to at least drive to the nearest workshop if there is a fault in the system.