Systems Operation 966H Wheel Loader and 972H Wheel Loader Electrohydraulic System Media Number -RENR8857-05
Publication Publica tion Date -01/10/2011
Date Updated -27/10/2011
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Solenoid Valves (Implement) SMCS - 5479-II
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g03094804 Illustration 1 Location for the Solenoid Valves on the Main Control Valve (1) Solenoid valve (tilt back) (2) Solenoid valve (lower) (3) Solenoid valve (dump) (4) Solenoid valve (raise)
g03094808 Illustration 2
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(6) Solenoid valve (auxiliary)
The following valves are solenoid valves (pilot proportioning).
Solenoid Valve (Raise) Solenoid Valve (Lower) Solenoid Valve (Dump) Solenoid Valve (Tilt Back) Solenoid Valve (Auxiliary or Third Function) Solenoid Valve (Auxiliary or Third Function)
NOTICE Solenoid coils will be damaged. Do NOT activate the solenoids with a voltage or signal that does not originate from the ECM.
Solenoid Valve (Pilot Proportioning)
g01192353 Illustration 3
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oil to the corresponding cylinder. When the operator moves a control lever or the joystick co ntrol the implement ECM activates the appropriate solenoid valve. The solenoid valves are energized with a PWM signal that is sent by b y the implement ECM. The PWM signal acts as a source of variable current to activate the solenoid. The solenoid valves have a connector with two contacts. One of the contacts will receive the input from the corresponding contact of the implement ECM (J1-48, J1-49, J1-51, J1-52, J1-58, J1-59). The output returns for the solenoid valves are the contact J1-50 and the contact J1-60 of the implement ECM. See the table below. Table 1 ECM Pin Terminal and Corresponding Description for the Main Control Valve Solenoids (Pilot Proportioning)
Pin
Description
J1-48
Raise Solenoid
J1-49
Lower Solenoid
J1-50
Return for the Lift and Tilt Solenoids
J1-51
Rack back Solenoid
J1-52
Dump Solenoid
J1-58
Auxiliary "HE" Solenoid
J1-59
Auxiliary "RE" Solenoid
J1-60
Return for the Auxiliary Solenoid Table 2 OUTPUT ENVELOPE
Current (Amp)
Lower (kPa-Psi)
Mean (kPa-Psi)
0
0
0
0.2
0
0
Upper (kPa-Psi)
25 kPa (3.5 psi) 25 kPa (3.5 psi)
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0.5 0.6 0.7 1 1.3 1.6 1.9
0
325 kPa (47 psi)
550 kPa (80 psi)
325 kPa (47 psi)
550 kPa (80 psi)
775 kPa (110 psi)
550 kPa (80 psi)
775 kPa (110 psi)
1000 kPa (145 psi)
1225 kPa (180 psi)
1450 kPa (210 psi)
1675 kPa (245 psi)
1900 kPa (275 psi)
2125 kPa (310 psi)
2350 kPa (340 psi)
2575 kPa (375 psi)
2800 kPa (405 psi)
3025 kPa (440 psi)
3250 kPa (470 psi)
3475 kPa (505 psi)
3700 kPa (535 psi)
Table 2 shows the relationship between the current that is going to the solenoid and the output pressure that results. As the current increases, increases, the pilot pressure increases. A pressure value below the lower limit or above the upper limit indicates that there is a problem in the hydraulic system. The pilot pressure can be monitored by b y attaching a pressure gauge to the end caps of the main control valve. Check the end cap that has the problem. Reference For additional information about checking the pilot pressure at the main control valve, refer to the Service Manual module Testing and Adjusting, "Pilot Pressure to the Main Control Valve - Check" for the machine that is being serviced.
Solenoid Valve (Hydraulic Lockout)
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g01192357 Illustration 4
The solenoid valve (hydraulic lockout) is an output of the implement ECM. The solenoid valve will disable the pilot hydraulics in failure mode. The solenoid valve (hydraulic lockout) will enable the pilot hydraulics, when the solenoid valve is energized by b y current from the implement ECM. The solenoid valve has a connector with two contacts. One contact receives power from connector contact J1-12 of the implement ECM. The other contact joins together with the other solenoid valves and returns to connector contact J2-4 of the implement ECM. Pin J1-42 supplies power to pin J1-12 within the implement ECM. If the input to J1-42 does not have battery voltage then the solenoid valve will not be energized.
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