DAF XF105. Manual - part 101

1

©

 200528

3-23

Control functions

DMCI ENGINE MANAGEMENT SYSTEM

XF105 series

- Intarder

In the case of the intarder a CAN message is sent 

via V-CAN2 if the maximum brake position is 

selected by the driver or if the coolant 

temperature exceeds a certain value during 

intarder activation. The vehicle braking is 

increased through the assistance of the engine 

brake during the maximum intarder brake 

position. 

If during intarder activation a programmed 

maximum coolant temperature is exceeded then 

the cooling system will be relieved through 

assistance from the engine brake.

Deactivation via V-CAN2
The engine brake activation can also be 

deactivated or blocked via a CAN message.

If ABS becomes active while the service brake is 

being used in combination with the engine brake, 

the engine brake is switched off. From the ABS/

EBS system the CAN message "ABS active" is 

sent to DMCI. DMCI will then deactivate the 

engine brake. When an attempt is made to 

activate the engine brake when ABS is active 

then activation of the engine brake will be 

blocked.

Also, if the wheels block during the use of the 

engine brake then a CAN message will be sent 

from the ABS/EBS system to DMCI to deactivate 

the engine brake temporarily. If the wheels turn 

again normally then the engine brake will be 

activated again.

Relevant components

-

Crankshaft sensor (F552)

-

Exhaust brake valve (B192)

-

DEB solenoid valves (B411 to B416)

-

VIC-2 (D310 via V-CAN1 and V-CAN2

-

Steering column switch (C907) via 

V-CAN1

-

Engine brake switch (E564) via V-CAN2

1

DMCI ENGINE MANAGEMENT SYSTEM

3-24

©

 200528

Control functions

XF105 series

3.12 FAN CLUTCH CONTROL

The purpose of the fan is to keep the coolant 

temperature below a specific maximum value. 

The valve in the fan clutch (B335) is opened or 

closed depending on various sensors. The fan 

clutch has a constant power supply of 24 V and is 

connected to earth with a duty cycle via pin C16. 

A high duty cycle means decreasing fan speed. A 

low duty cycle means increasing fan speed. The 

internal fan speed sensor feeds back the current 

fan speed to the DMCI electronic unit on pin C36. 

The electronic unit determines whether the fan 

clutch must be actuated more or less depending 

on this signal.

Note:

The fan always runs at high speed for a specific 

period after the engine is started. This is because 

some of the silicone fluid has settled and is in the 

working chamber. If the silicone fluid is cold as 

well, the fan will run at high speed for some time.

A number of different variables are taken into 

account in the fan clutch control:

1.

coolant temperature (F566)

2.

Air inlet temperature (F649)

3.

retarder activation (via V-CAN2);

4.

vehicle speed (via V-CAN2)

5.

internal slip protection.

Coolant temperature
From a specific coolant temperature (a), the 

minimum actuation of the fan clutch increases 

evenly with the coolant temperature. When a 

specific higher coolant temperature (b) is 

reached, the fan clutch is immediately actuated to 

maximum. If the coolant temperature drops again 

following this, actuation stays maximum until a 

specific lower coolant temperature (c) is reached 

and then decreases again evenly as the coolant 

temperature decreases.

i401016

D965

shield

N

5 1

supply  5V

signal

2

speed

fan

ground

T

R

1

signal

2

F566

temp.

coolant

B335

oct.

fan

4

3

ground

signal

C16

C31

C36

C35

supply

supply

supply

C60

C61

C62

Vehicle

CAN2

low

Vehicle
CAN2
high

E184
(10A)

N

2 1

signal

return

3

F552

speed

crankshaft

C26

C25

A49

A50

A60

CAN2 low

CAN2 high

B53

B45

0

0

Fan activation

max.

min.

low

high

hyst

Coolant
temp.

a

b

c

i400833

1

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 200528

3-25

Control functions

DMCI ENGINE MANAGEMENT SYSTEM

XF105 series

Activation of retarder
Two controls are used during activation of the 

retarder. A control that activates a time delay to 

control the fan clutch and a control that activates 

the fan clutch depending on the requested 

intarder braking power.

-

Intarder braking power

If the required braking power of the intarder is 

higher than a specific value, the intarder 

electronic unit will actuate the DMCI electronic 

unit to activate the fan clutch. This is to prevent 

excessive temperatures. The electronic unit will 

only increase actuation of the fan clutch above a 

specified low coolant temperature (a). Above a 

specified high temperature (b), the fan clutch is 

actuated to maximum. 

-

Time delay

Depending on the current coolant temperature at 

the time the intarder is activated, the fan clutch is 

switched on either with or without a delay. If the 

coolant temperature is low, the fan clutch will only 

be activated after a few seconds (a). If the coolant 

temperature is high, the fan clutch will be 

activated with a short delay (b). 

Vehicle speed
When the vehicle speed is low, there is little 

cooling from the air stream. Making activation of 

the fan clutch dependent on vehicle speed 

prevents the coolant temperature in the engine 

rising too rapidly. If the vehicle is stationary or is 

driving at low speed, the fan clutch will be 

activated with a high fan speed. Up to a specific 

vehicle speed (a), the fan speed will remain high 

and will then gradually decrease to a specific 

minimum fan speed at a specific higher vehicle 

speed (b).

0

0

Fan activation

max.

min.

low

high

Coolant
temp.

a

b

i400834

0

0

Time delay

long

short

low

high

Coolant
temp.

a

b

i400830

0

0

Fan activation

max.

min.

low

high

Vehicle
speed

a

b

i400829

1

DMCI ENGINE MANAGEMENT SYSTEM

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©

 200528

Control functions

XF105 series

internal slip protection
If the engine speed is high (> 2000 

rev

/

min.

) and 

the fan clutch speed is low, the viscous fluid may 

burn as a result of internal slip. In order to protect 

the viscous fluid from excessive temperatures, a 

specific speed range of the fan clutch is not used. 

If a fan speed (a) is reached at which there is the 

risk of the viscous fluid overheating, the fan clutch 

will not be actuated further. Only when a specific 

required speed (b) is reached will actuation 

increase to a maximum value. This means that 

the calculated required speed between a and b is 

not used. When the fan clutch actuation is 

maximum, the slip is minimum and the fan speed 

is maximum. If the required fan speed drops 

again, the fan clutch actuation stays maximum 

until a specific required speed (c) is reached, at 

which point actuation drops to level (a).

Relevant components

-

Coolant temperature sensor (F566)

-

Charge boost pressure and temperature 

sensor (F649)

-

Crankshaft sensor (F552)

-

intarder EST-42 (D902 via V-CAN2)

-

Intarder active

-

Tachograph (B525 via V-CAN2)

-

Vehicle speed signal

-

Electronically controlled fan clutch (B335)

0

0

Fan activation

max.

min.

low

a

b

c

i400831

high Fan speed