Content .. 86 87 88 89 ..

DAF XF105. Manual - part 88

200528

2-1

Description of components

DMCI ENGINE MANAGEMENT SYSTEM

XF105 series

2. DESCRIPTION OF COMPONENTS

2.1 DMCI ELECTRONIC UNIT

The electronic unit is mounted on the cylinder

block using rubber insulating bushes (3). The

electronic unit has three 62-pin connectors. Input

signals from various sensors are continuously

processed and compared with data stored in

various maps (tables) in the electronic unit.

Actuators are energised on the basis of the

signals received and the maps.

The housing (1) of the electronic unit is directly

connected to the engine block by an earth cable

(2). This earth connection is required because of

internal components which protect against radio

waves from outside.

The electronic unit incorporates an atmospheric

pressure sensor and a temperature sensor.

There is an air vent (4) for the atmospheric

pressure sensor in the housing of the electronic

unit.

An identification sticker (5) is attached to the

electronic unit.

The effect of atmospheric pressure on the
system:
-

the quantity of fuel injected when driving at

high altitudes (low air pressure).

If atmospheric pressure is low (in mountainous

areas), the air is thinner. When the air is thinner it

has a low density. The electronic unit uses this

information to control the turbocharger pressure

and adjust the quantity of fuel to be injected.

The effect of the internal temperature sensor
on the system:
-

none.

The internal temperature sensor measures the

temperature of the electronic unit. If the

temperature becomes too high, a fault code is

stored. The system does not take any further

action on the basis of this information.

Calibration

The performance of pump units and injectors may

differ slightly from one another as a result of small

production tolerances. These small production

differences are compensated for during

production by means of calibration in order to

optimise the engine output, exhaust gas

emissions and handling characteristics. A

calibration code is used to program the pump

units and injectors into the electronic unit

individually. The electronic unit modifies the

control of the pump units and injectors on the

basis of these calibration codes.

i400785

DMCI ENGINE MANAGEMENT SYSTEM

2-2

200528

Description of components

XF105 series

2.2 ACCELERATOR PEDAL SENSOR

The accelerator pedal sensor (F672) is mounted

on the accelerator pedal. The sensor (2) consists

of a potentiometer and a switch.

Potentiometer

The output signal (B33) from the potentiometer is

a linear voltage that has a fixed relationship with

the position of the accelerator pedal and

therefore is determined by the driver. The

potentiometer signal is the basis for determining

the quantity of fuel to be injected. The

potentiometer has a supply voltage (B34) and an

earth (B37) via the electronic unit.

Idling switch

Parallel to the potentiometer also the idling switch

is operated by depressing the accelerator pedal.

The idling switch is open in the no-load position

and is closed when the accelerator pedal is

operated. The switch is required for the

emergency function, when the potentiometer

signal is absent. This emergency function allows

the vehicle to be driven to a safe place or a

workshop if there is no potentiometer signal. One

side of the switch is connected to earth (B38) via

the electronic unit. The positive side (B41) is

connected to earth by means of the switch.

Kick-down switch

The kick-down switch (1) under the accelerator

pedal only acts to form a mechanical resistance

when the accelerator pedal is depressed. The

electronic unit detects the kick-down status

because the value of the output signal from the

potentiometer is higher than at full load. The kick-

down switch is for instance used to temporarily

disengage variable vehicle speed limiting so that

an automatic/automated gearbox can shift down

(in order to accelerate).

D965

F672

i400694

B34

4677

4679

4678

4166

4680

B33

B37

B38

B41

Kick-down switch

Accelerator pedal sensor

200528

2-3

Description of components

DMCI ENGINE MANAGEMENT SYSTEM

XF105 series

Effect of potentiometer output signal on the
system:
-

the basis for determining the quantity of fuel

to be injected.

engine brake disengaging/engaging

conditions

disengaging conditions of Downhill Speed

Control

CAN message accelerator pedal position,

via V-CAN1 (AS Tronic, AGC-A) and

V-CAN2 (EBS-2, VIC-2, builder module);

CAN message kickdown position active, via

V-CAN1 (AS Tronic, AGC-A);

Effect of idling switch output signal on the
system:
-

emergency function if the potentiometer is

not working.

engine brake disengaging/engaging

conditions

disengaging conditions of Downhill Speed

Control

CAN message idling switch active, via

V-CAN1 (AS Tronic) and V-CAN2 (VIC-2,

ZF intarder EST-42, EBS-2, DIP-4, builder

module)

DMCI ENGINE MANAGEMENT SYSTEM

2-4

200528

Description of components

XF105 series

2.3 COOLANT TEMPERATURE SENSOR

The coolant temperature sensor emits a signal

that indicates the temperature of the coolant and

therefore indirectly the engine temperature. The

sensor used is of the NTC (negative temperature

coefficient) type. The higher the temperature, the

lower the resistance of the sensor.

Effect of output signal on the system:
-

calculation of glowing time;

calculation of the quantity of fuel to be

injected and the injection timing;

calculation of actuation of the electronically

controlled fan clutch;

limiting of engine torque when temperature is

too high;

CAN message engine temperature, via

V-CAN2 to VIC-2 for display on the

instrument panel;

limitation of the maximum engine speed

when the engine is cold.

2.4 2

COOLANT TEMPERATURE SENSOR

The 2

coolant temperature sensor (F743) gives

a signal of the temperature of the coolant and

therefore indirectly of the engine at the level of

cylinder 6. The signal is compared by the

electronic unit (D965) to the signal from the

coolant sensor (F566) at the level of cylinder 1.

The sensor is of the NTC (Negative Temperature

Coefficient) type. The higher the temperature, the

lower the resistance of the sensor.

Effect of the signal on the system:
-

Detection of a cooling problem resulting in

engine torque limitation

i 400440

i401003

Content .. 86 87 88 89 ..