LINER-BEARING 3358221 - Caterpillar

engine's Electronic Control Module (ECM) controls the rpm of the engine fan by varying the current to the engine fan control solenoid. The engine fan control solenoid controls hydraulic oil pressure to the fan pump. The fan pump supplies hydraulic oil to the hydraulic fan motor.The engine cooling fan pump pressure sensor provides feedback to the ECM about the hydraulic oil pressure that is available at the fan pump. The ECM uses the feedback from the engine cooling fan pump pressure sensor by comparing the fan pump pressure to a set of fan pump pressure maps stored in the software of the ECM. The maps are based on the engine coolant temperature and the engine rpm. By using the engine coolant temperature and the pump pressure, the ECM calculates the desired fan drive pump pressure. If the fan's actual pump pressure is different from the calculated pressure, the ECM will vary the current to the engine fan control solenoid in order to change the pump pressure to the calculated pressure.The ECM controls the rpm of the engine fan in order to provide the following benefits:
Increased productivity
Noise from the fan is reduced.
Improved fuel economy
Overcooling of the engine is reduced.
Engine overspeed is limited.The ECM monitors engine coolant temperature. When the engine coolant temperature is low, the ECM limits fan rpm to a low rpm. As the engine coolant temperature rises, the ECM increases fan rpm. If engine coolant temperature continues to rise the ECM increases fan rpm until the engine coolant temperature stabilizes. When a system fault is detected, fan rpm is increased. When the engine is lugging, the fan rpm is reduced in order to reduce the load on the engine. When an engine overspeed occurs, the fan speed is increased in order to reduce the overshoot.The current to the engine fan control solenoid is a pulse width modulated signal. The signal varies between 0.1 (maximum fan rpm) to 1.9 amperes (minimum fan rpm). The ECM adjusts the current to the engine fan control solenoid in order to keep the fan rpm within 50 rpm of the desired rpm.An override is available with the Caterpillar Electronic Technician (ET). This allows the fan to be manually changed from the minimum to the maximum possible rpm. If the ECM detects a problem with the circuit for the engine fan control solenoid, a diagnostic code is generated. If the ECM detects a problem with the circuit for the engine fan control solenoid, the current to the solenoid is set to the minimum value. If the ECM detects a problem with the engine cooling fan pump pressure sensor, a diagnostic code is generated.