554 Forwarder and 574 Forwarder Hydraulic System Caterpillar

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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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Personal injury or death can result from escaping fluid under pressure. Escaping fluid under pressure, even a very small pin-hole size leak, can penetrate body tissue and cause serious injury and possible death. If fluid is injected into your skin, it must be treated immediately by a doctor familiar with this type of injury. Always use a board or cardboard when checking for a leak.

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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 bucket and/or attachments to the ground and engage the parking brake. Stop the engine and remove the key. Block the wheels and install the steering frame lock.

The IQAN monitors the condition of the machine and the operation of the machine. The IQAN should be used as the first step in troubleshooting a problem with the electrohydraulic system. The IQAN allows you to test the electrical signals that are inputs to the IQAN. The IQAN also allows you to test the electrical signals that are outputs from the IQAN.

For a hydraulic component to function correctly the following conditions must exist:

• The IQAN must receive the correct electrical signal from the switch or the joystick control.

• The solenoid must receive the correct electrical signal from the IQAN.

• Pilot pressure oil must flow to the valve spool for the hydraulic component.

• System pressure oil must flow to the hydraulic component.

When a hydraulic component does not operate, perform the following steps to diagnose the problem:

1. Check the electrical signal from the joystick control or the switch. If the IQAN does not receive the signal, check the wiring harness, switches, and control levers. If the IQAN receives the correct signal continue to Step 2.

2. Check the outputs from the IQAN to the solenoids. With a stopped engine and the engine start key in the ON position, use the IQAN to check the output to the solenoid. The magnitude of the current must be correct for the solenoid to activate. If the magnitude of the current is correct, perform Step 3.

3. Measure the current to the solenoid. Ensure that the output current from the IQAN flows to the solenoid. If output current does not flow to the solenoid, check the wiring harnesses between the IQAN and the solenoid.

4. If the function still does not operate correctly, perform the following inspection:
   • Check the system pressure of the oil for the component.

   • Check for pilot pressure in the valve for the component.

   • Ensure that no air is present in the pilot system.

   • Inspect the hydraulic oil lines from the valve to the component for restrictions and leaks.

   • Inspect the components for wear and obstructions.

   • Inspect the valve spool for wear and abrasions.

The IQAN can also be used to check the operation of the sensors on the machine. In the function state of the IQAN, the "Measure" sub-menu can be used to display the inputs and outputs to the IQAN. The "Trim" sub-menu can be used to adjust the current to the solenoids in the implement control valve and the bogie control valve.

ReferenceFor more information on using the IQAN for troubleshooting, refer to Operation and Maintenance Manual, SEBU7197, "554 Forwarder and 574 Forwarder", "Monitoring and Control System".