Ch 6 page 45
ELECTRICAL SYSTEM
SHOP MANUAL
Cooling fan control
The VCU2 is controlling the cooling fan using various temperature parameters.
The hydraulic part consists of two solenoids. One proportional for speed control, and one valve for stopping the
fan.
Fan speed is defined as follows:
0% = fan stopped
1% = fan at minimum speed (approx. 270rpm). Solenoid drive = 800mA
100% = fan at maximum speed (approx. 1450rpm). Solenoid drive = 180mA
The temperatures parameters are as follows:
Engine coolant temperature (measured on engine via canbus):
>5°C = 0%
5-82°C = 1%
83-94°C = 1-100%
>94°C = 100%
Transmission sump temperature (measured on transmission via canbus):
>5°C = 0%
5-85°C = 1%
86-100°C = 1-100%
>100°C = 100%
Retarder temperature (measured on transmission via canbus):
>10°C = 0%
10-94°C = 1%
95-112°C = 1-100%
>112°C = 100%
Front WDB oil temperature (DA40 only, measured via VCU2):
>10°C = 0%
10-74°C = 1%
75-115°C = 1-100%
>115°C = 100%
Charge air compensated temperature (measured on engine via canbus and in front of cooling pack):
The fan is controlled to maintain a maximum 25°C rise in charge air temperature in respect to the ambient tem-
perature.
The reference ambient temperature is measured in the front of the cooling package.
If the ambient temperature is < 25°C the reference is set to 25°C.
If the ambient temperature is > 55°C the reference is set to 55°C.
Temperature difference (charge_air – reference):
<=0°C = 0%
1-15°C = 1%
15-25°C = 1-100%
>25°C = 100%
If any of the above sensors is missing of faulty the fan speed is forced to 100%.
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