938G Wheel Loader and IT38G Integrated Toolcarrier Hydraulic System Caterpillar

Solenoid Valve (Pilot Diverter, 4 Function Hydraulics) Operation - Check

Usage:

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Personal injury can result from hydraulic oil pressure and hot oil.
Hydraulic oil pressure can remain in the hydraulic system after the engine has been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic system.

Make sure all of the attachments have been lowered, oil is cool before removing any components or lines. Remove the oil filler cap only when the engine is stopped, and the filler cap is cool enough to touch with your bare hand.

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Sudden movement or accidental starting of the machine can cause personal injury or death to persons on or near the machine.
To prevent personal injury or death, perform the following:
Park the machine on a smooth, level surface.
Lower the work tool to the ground and engage the parking brake.
Stop the engine and remove the key.

Block the wheels and install the steering frame lock.

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NOTICE

Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Caterpillar Tools and Shop Products Guide" for tools and supplies suitable to collect and contain fluids on Caterpillar products. Dispose of all fluids according to local regulations and mandates.

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Table 1
Required Tools
Part Number	Description	Qty
1U-5481	Pressure Gauge Group	1
1U-5482	Pressure Adapter Group	1
4C-4892	ORFS Fittings Group	1
8S-7630 ⁽¹⁾	Stand	2
8S-7641 ⁽¹⁾	Tube	2
8S-8048 ⁽¹⁾	Saddle	2
8S-7615 ⁽¹⁾	Pin	2
6V-9508	Plug	2
6V-8397	O-Ring Seal	3
6V-9829	Cap	1

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^( 1 )

Optional tooling

The pilot diverter solenoid valve is an electrohydraulic valve. The pilot diverter solenoid valve controls the flow of pilot oil to either the tilt control valve spool or the fourth function control valve spool. When the fourth function switch is actuated the pilot diverter solenoid valve supplies pilot oil to the fourth function control valve spool.

This procedure will measure the pilot oil pressure that is going to the fourth function control valve spool. This will verify that the pilot diverter valve is operating correctly.

Start the engine. Run the engine at high idle. Operate the control levers and move all the cylinders in order to increase the temperature of the hydraulic oil to normal operating temperature.

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Illustration 1	g00298585
Jack Stands

Lower the lift arms to the ground or onto jack stands.

Shut off the engine.

Prepare the machine for testing. For more information, refer to the Service Manual module Testing and Adjusting, "Machine Preparation for Troubleshooting" for the machine that is being serviced.

Release the pressure in the hydraulic system. For more information about releasing hydraulic system pressure, refer to the Service Manual module Testing and Adjusting, "System Pressure - Release" for the machine that is being serviced.

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Illustration 2	g00517776
Loader Tower Access Panel Lift arms raised for photographic purposes only.

Remove the cover that is over the main control valves in order to access the fourth function valve spool.

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Illustration 3	g00517350
Pilot Diverter Valve (Fourth Function) (1) Manifolds. (2) Adapters. (3) Tube assemblies.

Disconnect tube assemblies (3).
Note: The opposite ends of the tube assemblies are connected to the fourth function valve spool.

Install a 8T-8902 Tee with a 6V-8397 O-Ring Seal onto one of the adapters (2). Install a 6V-9829 Cap with a 6V-8397 O-Ring Seal onto the opposite end of the tee. Install a 6V-3965 Fitting Assembly (Test) with a 3J-1907 O-Ring Seal onto the 8T-8902 Tee .

Install a 6V-9829 Cap with a 6V-8397 O-Ring Seal on the other adapter.

Install 6V-9508 Plugs and 6V-8397 O-rings into tube assemblies (3). Refer to Illustration 3 for the location of the tube assemblies.

Attach one end of a 177-7861 Hose Assembly onto the 6V-3965 Fitting Assembly (Test). Attach the opposite end of the hose assembly to the 8T-0850 Pressure Gauge (0 to 4,000 kPa (0 to 580 psi)).

Start the engine and warm the hydraulic oil to a normal operating temperature of approximately 50 to 65°C (120 to 150°F).

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Illustration 4	g00515054
Operator Control Console (3) Fourth function switch. (4) Tilt control lever.

Actuate the fourth function switch. The tilt control lever should now control the fourth function valve spool.

Run the engine at low idle. Move the tilt control lever to the position which pressurizes the chamber that is being tested and record the pressure gauge reading. The minimum pressure should be 2070 kPa (300 psi).
This is the pressure at the end of the main control valve spool. The pressure reading should be equal to pilot system pressure.

If you are unable to record any pressure, the solenoid valve is not functioning.

Shut off the engine. If the pressure reading is within specifications, repeat Steps 7 through 15 for the other side of the fourth function valve spool.