What is Hitachi ZX670LC-5A Fault Code 14106-2?

Fault Code 14106-2 on the Hitachi ZX670LC-5A excavator indicates a Swing Motor Solenoid Valve Circuit Malfunction with an abnormal current or voltage condition. This diagnostic trouble code (DTC) specifically relates to the electrical circuit controlling the swing motor's proportional solenoid valve, which regulates hydraulic flow to the upper structure rotation system.

This code is critical for the ZX670LC-5A because the swing motor system is fundamental to operational efficiency on this 68-ton machine. When the Engine Control Module (ECM) or hydraulic controller detects current values outside specified parameters (typically 0.5-1.2 amps depending on joystick input), it triggers this fault to prevent potential damage to the solenoid valve coil or hydraulic components. For used excavators, this code often signals deteriorating electrical connections or wear in the valve assembly itself.

Common Symptoms

• Intermittent or complete loss of swing function, with the upper structure failing to rotate smoothly or at all
• Swing motion becomes jerky or unresponsive to joystick commands, particularly at low RPM
• Warning light illumination on the instrument cluster, often accompanied by a beep alert
• Reduced swing speed or inconsistent torque during rotation, especially under load
• Error message display on the monitor panel showing code 14106-2 when accessed through diagnostic mode

Potential Causes

The most common technical causes for this fault code on used ZX670LC-5A excavators include:

• Damaged or corroded wiring harness at known friction points near the swing bearing race, where cables experience constant flexing
• Failed proportional solenoid valve coil within the main control valve assembly, often due to overheating or moisture ingress
• Shorted or open circuit in the connector pins at the swing motor solenoid valve (check connector C-314 specifically)
• ECM internal fault or poor ground connections at the controller mounting points
• Hydraulic contamination causing the solenoid spool to stick, creating abnormal current draw
• Deteriorated connector seals allowing moisture into the electrical system—common in machines over 8,000 operating hours

How to Troubleshoot and Fix Code 14106-2

Step 1: Visual Inspection and Connector Check Begin by inspecting the swing motor solenoid valve connector located on the main control valve. Disconnect connector C-314 and examine pins for corrosion, bent contacts, or oil contamination. Clean with electrical contact cleaner and check connector seals for deterioration—a critical step for used excavators.

Step 2: Electrical Testing with Multimeter Using a quality digital multimeter, measure the solenoid coil resistance with the connector disconnected. The specification should be approximately 8-12 ohms (consult your service manual for exact values). Next, check for supply voltage at the harness side with ignition on—you should see approximately 12-24V DC. Measure current draw while operating the swing function using a clamp meter; readings above 1.5 amps indicate a shorted coil.

Step 3: Harness and Ground Circuit Verification Trace the wiring harness from the solenoid valve back to the ECM, paying special attention to areas where cables pass through the swing bearing area. Look for abraded insulation, especially near metal edges. Verify ground circuit continuity; resistance should be less than 1 ohm to chassis ground.

Step 4: Component Replacement or ECM Diagnosis If resistance and voltage tests fail, replace the swing motor solenoid valve assembly. For used excavators with over 10,000 hours, consider replacing the entire wiring harness segment if multiple abrasion points exist. If all electrical tests pass but the code persists, connect Hitachi Dr.EX diagnostic software to check for ECM programming issues or internal controller faults.

Disclaimer: This guide provides general troubleshooting information. Always consult the official Hitachi service manual for your specific serial number and seek qualified technician assistance for complex hydraulic or electrical repairs.