BODY-VALVE 8J7289 - Caterpillar

Outputs
The ECM responds to inputs by sending electrical signals to the outputs. The outputs can create an action or the outputs can provide information to the operator or service technician.On/Off Solenoids
For control of on/off type solenoids and relays, the ECM will either turn ON or turn OFF the output for a component. The output command is based on the signals from the input devices that are involved in the system. The ECM will not vary the amplitude of the output, the circuit is either energized (on) or the circuit is de-energized (off). When the on/off output circuit is energized, most often system power will be used to energize the circuit and the output component.
Illustration 7 g01158530Note: The values in Table 3 are for bench testing only. Values may not represent parameters for machine systems specifications.
Table 3
Rated Voltage 24 VDC
Coil Resistance 32.0 3.2Ω (T=20° C) The medium pressure hydraulic system contains the following on/off solenoids:
Joystick steering enable solenoidPWM Solenoid Outputs
To control the proportional solenoid valves, the ECM will use a pulse width modulated (PWM) signal to energize the solenoids. The ECM will vary the duty cycle of the PWM signal to control the amount of electrical current that is sent to the proportional solenoids. A PWM duty cycle is the percentage of time that the signal is "high" compared to the amount of time that the signal is "low". As the duration of the high signal increases, the percentage of the duty cycle and the amount of electrical current in the circuit will increase.To control a solenoid, the ECM will depend on the input signals involved in the control of the system to apply the correct current. The distance of travel of the solenoid valve plunger is proportional to the electrical current that is sent by the ECM. The position of the valve plunger controls the amount of pilot oil pressure that is applied to the valve spool. As the ECM increases the current to a solenoid, the spool allows more hydraulic oil flow to the hydraulic cylinders. This condition will cause the rate of movement of the implement to increase. As the ECM decreases the current to a solenoid, the pilot oil flow decreases. The spool allows less hydraulic oil flow to the hydraulic cylinders, and the movement of the implement will decrease.Cab Raiser
The cab raiser solenoids are mounted on the medium pressure valve stack. Refer to the illustrations at the beginning of this section for the machine location.The ECM will control the outputs for the attachment that is installed based on the input from the cab raiser enable switch and the right joystick thumb wheel position sensor.Note: The right joystick thumb wheel PWM duty cycle input is approximately 5 percent at the full left position and approximately 95 percent at the full right position. The duty cycle is at approximately 50 percent at the center position.When the thumb wheel is moved to the left in order to raise the cab, the ECM will send a PWM signal