PIN 1745641 - Caterpillar

The electronic control system consists of monitor (15) and the machine ECM (1) that is located in the cab. The electronic control system controls the engine speed and the pumps through the machine ECM.Machine ECM (1) receives input signals from various components on the machine. The machine ECM continuously monitors the input signals in order to control the output flow rate of the main pumps, engine speed, and various components of the machine hydraulic systems.The machine ECM has the following three major functions.
The electronic control system controls the output flow rate of the main pumps. The machine ECM sends an electrical signal to the power shift solenoid that is based on engine speed and the position of the engine speed dial. This action allows the main pumps to supply the optimum output that matches the hydraulic load to the machine and the engine speed. When a large load is placed on the machine, the system allows the pumps to destroke. The system utilizes the available maximum engine horsepower.
The electronic control system controls the engine speed. This function is called Automatic Engine Speed Control (AEC). When there is a small load condition or no load condition, the system automatically decreases the engine speed. The AEC system is designed to reduce fuel consumption and noise.
The electronic control system controls various components of the machine hydraulic systems. The machine ECM sends output signals to the swing brake solenoid valve, the travel speed solenoid valve and the straight travel solenoid.Reference: For more information concerning the operation of the electronic control system, refer to Systems Operation/Testing and Adjusting, "Machine Electronic Control System".ECM Logic
The machine ECM receives input signals from various pressure sensors and pressure switches on the machine. The machine ECM monitors the input signals in order to control various functions of the hydraulic system.Pressure Sensors
Drive pump pressure sensor and idler pump pressure sensor
Drive pump and idler pump pressure sensors measure the pump discharge pressure. The pressure sensors send a pulse width modulated signal (PWM) input to the machine ECM. The pressure information is used for pump control and travel speed change.Boom cylinder head end pressure sensor
Boom cylinder head end pressure sensor measures the hydraulic pressure on the head end of the boom cylinder. The pressure sensors send a pulse width modulated signal (PWM) input to the machine ECM. The pressure information is used for boom regeneration control.Pressure sensor for boom down control
Pressure sensor for boom down control measures the pilot oil pressure during a boom DOWN function. The pressure sensor for boom down control sends a pulse width modulated signal (PWM) input to the machine ECM. The machine ECM uses the pressure information to reduce engine speed and pump flow during a boom down function. Also, whenever the pilot pressure exceeds 500 kPa (73 psi) the machine ECM energizes swing brake solenoid valve (24). This action releases the swing parking brake.Pressure sensors for negative flow control
Pressure sensor for the drive pump and pressure sensor for the idler pump measures the negative flow