FUSE 3962574 - Caterpillar

Normal Operation
The ECM monitors the position of the hydraulic levers that are located in the operator compartment. When the levers are moved, the ECM detects the amount of movement. The ECM then activates the corresponding solenoid valve. The ECM activates the valve in the proper amount in order to move the bucket at the appropriate speed.The ECM electronically controls the hydraulic pilot valves for the bucket and any auxiliary hydraulic attachments. Sensors that are connected to the hydraulic control levers detect requests of the operator. The ECM reads these sensor signals. The ECM causes the corresponding hydraulic cylinder to move by activating the appropriate solenoid valve. If the hydraulic control lever is barely moved the ECM will activate the solenoid valve enough to slowly move the cylinder. If the lever is moved more, the ECM activates the solenoid valve more and this causes the cylinder to move faster.The pilot ON/OFF solenoid valve is activated by the ECM whenever the engine is running. This is not true if the implement lockout switch is in the locked position.
Illustration 1 g00447024
Lever RAISE ModulationIllustration 1 represents the interpretation by the implement ECM of the signal from the lift lever when the lever is in the RAISE position. As the lever is moved away from the center, no current is supplied to the lift raise solenoid until the lever is three degrees from the center. At three degrees of lever travel, the ECM supplies Start of Modulation Current (1) to the raise solenoid. As the lever is moved toward the detent, the current that is supplied to the raise solenoid increases. The increase is linear up to the Raise Maximum Modulation Current (2). The maximum modulation current is reached just before the lever enters the detent position. Entering the detent position does not increase the current more.
Illustration 2 g00447025
Lever Lower ModulationIllustration 2 represents the interpretation by the implement ECM of the signal from the lift lever when the lever is in the LOWER position. As the lever is moved away from the center, no current is supplied to the lift lower solenoid until the lever is three degrees from the center. At three degrees of lever travel, the ECM supplies Start of Modulation Current (3) to the lower solenoid. As the lever is moved toward the detent, the current that is supplied to the lower solenoid increases. The increase is linear up to the Lower Maximum Modulation Current (4). The maximum modulation current is reached just before the lever enters the detent position. As the lever is moved into the detent position, the ECM will increase the current. As the current level increases, the pilot pressure will also increase. The main valve will go into the FLOAT position when the pilot pressure has increased sufficiently.Note: The Start of Modulation Current must be adjusted for each valvein order to provide sufficient pilot pressure for shifting the main valve spool. When the main valve spool shifts, hydraulic oil flows to the cylinders. The Start of Modulation Current