What is Hitachi ZX210LCK-5G Fault Code 20106-2?

Fault Code 20106-2 on the Hitachi ZX210LCK-5G indicates a hydraulic pump solenoid valve circuit malfunction, specifically detecting an abnormal voltage or open circuit condition in the main pump control solenoid. This code is generated when the machine's Electronic Control Module (ECM) identifies that the electrical signal to the hydraulic pump's proportional solenoid valve is outside the acceptable voltage range or has lost continuity entirely.

This fault is critical because the pump solenoid valve regulates hydraulic flow and pressure throughout the excavator's entire hydraulic system. When this circuit fails, the ECM cannot properly control engine load matching or optimize fuel efficiency, directly impacting digging force, swing speed, and overall machine performance. On the ZX210LCK-5G model, this can trigger protective modes that significantly reduce operational capability.

Common Symptoms

• Reduced hydraulic power across all functions, with noticeably slower boom, arm, and bucket movements
• Engine over-revving without corresponding hydraulic response due to loss of load-sensing feedback
• Warning light activation on the instrument cluster, often accompanied by an audible alarm
• Erratic or unresponsive controls, particularly during combined multi-function operations
• Increased fuel consumption as the ECM defaults to open-loop operation without proper pump control

Potential Causes

The most common causes for Code 20106-2 on used ZX210LCK-5G excavators include:

• Damaged wiring harness near the main pump assembly, where vibration and heat cause insulation breakdown and wire chafing
• Corroded or loose connector pins at the solenoid valve plug, especially in machines operated in wet or marine environments
• Failed proportional solenoid valve due to internal coil deterioration or contaminated hydraulic oil causing mechanical binding
• ECM internal circuit failure, though less common, can occur in higher-hour machines (typically above 8,000 hours)
• Voltage supply issues from the main power harness, including poor grounding points common to this model year

How to Troubleshoot and Fix Code 20106-2

Step 1: Visual Inspection Disconnect the battery and inspect the pump solenoid connector for corrosion, bent pins, or moisture intrusion. On used excavators, check the wiring harness routing from the ECM to the pump—look specifically for rub points against the pump housing or engine block where insulation may be worn through.

Step 2: Electrical Testing Using a digital multimeter, measure solenoid coil resistance at the valve connector (disconnected). Typical resistance should be 3-6 ohms; refer to the Hitachi service manual for exact specifications. Next, check for supply voltage at the harness side—you should see battery voltage (12V) with the key on. Measure ground continuity to ensure less than 1 ohm resistance.

Step 3: Component Testing If electrical values are correct, the solenoid valve itself may be mechanically failed. Remove the valve and check for physical damage or debris. For used machines, replacing aged connectors and applying dielectric grease often resolves intermittent codes before expensive component replacement. Use Hitachi diagnostic software (Dr.EX) to perform active solenoid tests and monitor real-time voltage signals.

Disclaimer: This guide provides general troubleshooting information. Always consult the official Hitachi service manual and consider professional diagnostic assistance for complex electrical issues, especially on used equipment with unknown service history.