What is Hitachi ZX470LCH-5G Fault Code 20106-2?

Fault Code 20106-2 indicates a communication error or voltage abnormality in the machine's Controller Area Network (CAN) bus system, specifically related to the hydraulic pump control circuit. This diagnostic trouble code (DTC) is triggered when the Engine Control Module (ECM) detects irregular signal transmission between the pump controller and the main machine controller, or when voltage readings fall outside the manufacturer's specified range of 4.5-5.5 volts.

For the ZX470LCH-5G excavator, this fault is particularly critical because it directly affects the proportional pressure control system that governs hydraulic flow and implement responsiveness. When this code activates, the machine's computerized load-sensing system cannot properly modulate pump output, leading to reduced operational efficiency and potential component damage if left unaddressed.

Common Symptoms

• Reduced hydraulic power across all functions, with noticeably slower boom, arm, and bucket movements
• Intermittent or complete loss of attachment response, especially during combined multi-function operations
• Yellow warning lamp illumination on the instrument cluster, sometimes accompanied by audible alarm
• Erratic engine RPM fluctuations when hydraulic functions are engaged under load
• Error message displayed on the monitor panel indicating communication fault or system malfunction

Potential Causes

The most common technical failures triggering Code 20106-2 on used ZX470LCH-5G excavators include:

• Corroded or damaged wiring harness connectors at the pump controller junction box (known wear point near the hydraulic tank mounting area)
• Failed pump solenoid valve or its associated position sensor experiencing internal electrical short
• CAN bus termination resistor failure causing signal reflection and communication errors
• Degraded main wiring harness with insulation breakdown due to heat exposure from hydraulic oil lines
• ECM internal fault or corrupted calibration data (less common but possible in high-hour machines)
• Low system voltage from aging batteries or failing alternator affecting sensor reference voltage

How to Troubleshoot and Fix Code 20106-2

Step 1: Initial Electrical Inspection Connect a diagnostic laptop with Hitachi Dr.EX software to retrieve freeze-frame data and active parameters. Use a digital multimeter to verify battery voltage (should read 24-28V with engine running). Inspect all ground connections at the pump controller mounting bracket and clean corrosion.

Step 2: Harness and Connector Verification Physically inspect the pump controller harness routing along the right-side chassis rail where it passes near hydraulic lines—this is a known friction point on used machines. Check connector C-407 (8-pin pump solenoid connector) for bent pins, moisture intrusion, or green oxidation. Measure resistance between CAN-High and CAN-Low terminals (should read 60 ohms with ignition off).

Step 3: Component Testing With ignition on and engine off, backprobe the pump pressure sensor signal wire (typically yellow/blue) and verify 5-volt reference supply. Test the proportional solenoid by measuring resistance across its terminals (spec: 18-22 ohms at 20°C). If readings are abnormal, replace the solenoid valve assembly (Hitachi part #4644177).

Step 4: CAN Bus Verification Use an oscilloscope to check CAN signal integrity—waveforms should show clean differential signals between 2.5-3.5V. Replace termination resistors if readings exceed 65 ohms. For persistent issues on high-hour used excavators, reflash the ECM software to latest calibration using authorized Hitachi diagnostic tools.

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Disclaimer: This guide provides general troubleshooting procedures for informational purposes. Always consult the official Hitachi service manual for your specific machine serial number and seek assistance from certified heavy equipment technicians for complex electrical diagnostics and repairs.