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| Illustration 1 | g00869091 |
Component Location of the Pilot Valve (Oil Manifold)
(1) Solenoid valve (tilt right). (2) Solenoid valve (raise). (3) Solenoid valve (tip back). (4) Pilot on/off solenoid valve. (5) Solenoid valve (tilt left). (7) Solenoid valve (lower). (8) Solenoid valve (tip forward).
Note: Illustration 1 shows the pilot valve (oil manifold) for the 824H II Wheel Dozer. The 825H II Soil Compactor and the 826G II Landfill Compactor are not equipped with the attached valve for the tip function. The 826H II Landfill Compactor will not be equipped with the proportional solenoid valve (1) and proportional solenoid valve (5).
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| Illustration 2 | g00819052 |
Proportional Solenoid Valve | |
The solenoid valves are outputs of the implement ECM. The purpose of the solenoid valves is to direct pilot oil to the main control valves. The control valve spool shifts in order to allow pressure oil to the corresponding cylinder. When the operator moves the joystick control the ECM activates the appropriate solenoid valves. The solenoid valves are energized with a PWM signal that is sent by the ECM. The PWM signal acts as a source of variable current to activate the solenoid. Do not check voltage across the solenoid. The maximum current that is available to the solenoids is 850 mA.
The solenoid valves have a connector with two contacts. One contact receives power from the corresponding connector contact of the ECM (J2-8, J2-1, J1-10, J1-4, J1-11 and J1-17). The contacts for the solenoid valves return through contact J1-7 and contact J2-3 of the ECM.
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| Illustration 3 | g00452286 |
Proportional Solenoid (Input Current) versus Output Pressure | |
Illustration 3 shows the relationship between the current that is going to the solenoid and the output pressure that results. As the current increases, the pilot pressure increases. The dashed lines on each side of the solid line indicate the acceptable range. A pressure value which is outside of the acceptable range indicates that there is a problem in the hydraulic system. The pilot pressure can be monitored by attaching a pressure gauge to the individual end caps of the main control valve.
Reference: For additional information about checking the pilot chamber pressure, refer to the Service Manual module Testing and Adjusting, "Pilot Pressure to the Main Control Valve - Check" for the machine that is being serviced.
| NOTICE |
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Solenoid coils will be damaged. Do NOT activate the solenoids with a voltage or signal that does not originate from the ECM. |
Pilot On/Off Solenoid Valve
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| Illustration 4 | g00335122 |
Pilot On/Off Solenoid Valve | |
The pilot on/off solenoid valve is an output of the implement ECM. The pilot on/off solenoid valve will disable the pilot hydraulics in failure mode. The pilot on/off solenoid valve will enable the pilot hydraulics, when the pilot on/off solenoid valve is energized by a constant voltage from the ECM. The pilot on/off solenoid valve has a connector with two contacts. One contact receives power from connector contact J1-8 of the ECM. The other contact joins together with the other solenoid valves and returns to connector contact J1-7 and J2-3 of the ECM. Pin J1-40 supplies power to pin J1-8 within the implement ECM. If the input to J1-40 does not have battery voltage then the pilot on/off solenoid valve will not be energized.