PLUG 0027034 - Caterpillar

Illustration 5 g01876938
Location of the "Steering Valve" solenoids (wide view)
The solenoid valves for the steering pump are outputs of the ECM. The ECM uses these solenoid valves to steer the machine. The solenoids control the direction and the amount of the pump oil displacement. Each solenoid has a connector with two contacts. One contact receives a signal from the corresponding J1-67 or J1-68 connector contact of the ECM. The other contact of each solenoid is connected to the return circuit of the solenoid at J1-54. Note: The solenoid coils are not designed for the operation of 24 VDC directly. The ECM sends a 24 volt PWM signal at a duty cycle which provides the necessary current to the solenoid coils. Do NOT activate the coils with 24 VDC (+battery). This will cause the life of the coils to be reduced drastically. Use 12 VDC if the coils must be activated without the ECM. The solenoids are the proportional type. The ECM uses a pulse width modulated signal (PWM) in order to vary the current