BEARING 0898909 - Caterpillar

Input Signals
Illustration 1 g06175757
Fan Control System
(1) Engine ECM
(2) Engine coolant temperature sensor
(3) ATAAC air temperature sensor
(4) Hydraulic oil temperature sensor
(5) Fan solenoid
(6) Output signal
(7) Input signalNote: The blue lines in the illustration indicate an input signal. The red lines indicate an output signal.Note: The illustration shows the general layout of the fan control system. Refer to the machine electrical schematic for detailed wiring information.Engine ECM (1) uses input signals from the following devices to control fan solenoid (5):
Engine coolant temperature sensor (2)
ATAAC air temperature sensor (3)
Hydraulic oil temperature sensor (4)Output Signals
Engine ECM (1) controls fan speed through fan solenoid (5), which is mounted on the fan pump. Once the engine ECM calculates the target fan speed, the ECM generates a proportional output signal to the solenoid.The signal sent to fan solenoid (5) is inversely proportional to the fan speed. The greater the output signal, the slower the speed of the fan. The minimum and maximum solenoid currents can be adjusted with the Caterpillar ET software.Operating Logic
Software in engine ECM (1) contains the fan control logic. This logic uses an open-loop strategy for fan speed control.The fan control logic compares the temperature values from the sensors to the programmed set points. When the temperature values are less than the corresponding set point value, the engine ECM operates the fan at minimum speed. If the temperature value of a monitored parameter exceeds the set point, the engine ECM increases the fan speed.