What is Hitachi ZX890H-5A Fault Code 14106-2?

Fault Code 14106-2 indicates a malfunction in the Engine Control Module (ECM) power supply circuit, specifically a voltage irregularity or interruption in the primary power feed to the engine's electronic control system. This code is triggered when the ECM detects that incoming voltage falls outside the acceptable range (typically 20-32V for this model) or experiences intermittent power loss.

In the Hitachi ZX890H-5A hydraulic excavator, this fault directly affects the HCMC (Hitachi Construction Machinery Control) system's ability to regulate engine performance, fuel injection timing, and emissions controls. The ECM serves as the brain of the engine management system, and any power supply disruption compromises critical functions including turbocharger boost control, common rail fuel pressure, and exhaust gas recirculation (EGR) management. For a machine of this size class (operating weight approximately 196,000 lbs), maintaining stable ECM power is essential for both performance and preventing costly engine protection shutdowns during heavy excavation work.

Common Symptoms

• Engine warning lamp illuminated on the instrument cluster, often accompanied by a check engine light or dedicated ECM fault indicator
• Unexpected engine derating or power reduction mode, limiting maximum RPM to 1400-1600 range to protect engine components
• Intermittent engine stalling or rough idle, particularly when electrical loads increase (lights, A/C, or hydraulic heaters activated)
• Difficulty starting the engine, especially during cold weather conditions when battery voltage naturally drops
• Erratic gauge readings on the monitor panel, including fuel level, coolant temperature, or hydraulic oil temperature fluctuations

Potential Causes

The most common technical causes for Code 14106-2 on used ZX890H-5A excavators include:

• Battery terminal corrosion or loose connections reducing voltage supply to the main power distribution harness
• Damaged or chafed wiring harness between the battery and ECM, particularly at known rub points near the engine mount brackets and along the right-side frame rail
• Failing alternator unable to maintain proper charging voltage (should output 28V minimum on this 24V system)
• Corroded or loose ground connections at the ECM mounting location or engine block ground straps
• Defective main power relay in the cab fuse box that supplies switched power to the ECM
• Internal ECM power supply circuit failure, though less common than external wiring issues in higher-hour used machines

How to Troubleshoot and Fix Code 14106-2

Step 1: Perform Visual Inspection and Voltage Testing Begin with the batteries disconnected. Inspect all battery terminals, main power cables, and ground straps for corrosion, fraying, or looseness. Clean terminals with a wire brush and apply dielectric grease. Reconnect batteries and use a digital multimeter to measure voltage at the battery (should read 24-26V with engine off). Start the engine and verify charging voltage reaches 28-29V. Check for voltage drop across ground connections—readings above 0.2V indicate resistance problems requiring cleaning or replacement.

Step 2: Inspect ECM Power Supply Harness Locate the main ECM connector (typically a 120-pin connector on the left side of the engine). With the key in the ON position (engine off), back-probe the power supply pins (consult service manual for exact pin locations) and verify 24V presence. On used excavators, carefully trace the harness from the cab fuse box to the ECM, checking for chafing points where the harness crosses frame members or contacts sharp edges. Pay special attention to areas near the hydraulic tank and engine mounts where vibration causes wear over thousands of operating hours.

Step 3: Test Alternator and Power Relay Function Using Hitachi Dr.EX diagnostic software or a compatible scan tool, monitor real-time ECM supply voltage while increasing electrical loads (turn on work lights, cab heater, windshield wipers). Voltage should remain above 26V under load. If voltage drops significantly, load-test the alternator (should produce 150+ amps on this model). Check the main power relay in the fuse panel by swapping with an identical relay or testing coil resistance (70-90 ohms typical). For used machines with 8,000+ operating hours, replace suspect relays preventatively as internal contact degradation is common.

Step 4: ECM and Connector Inspection If external circuits test normal, inspect the ECM connector pins for corrosion, bent terminals, or moisture intrusion. Remove the connector and examine both male and female terminals under magnification. Green corrosion on pins indicates water infiltration—clean with electrical contact cleaner and seal with OEM connector grease. On used excavators stored outdoors, connector corrosion is a frequent cause of intermittent power codes. If all external components test satisfactory, the ECM internal power supply circuit may require professional ECM repair or replacement.

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Disclaimer: This guide provides general troubleshooting information for experienced technicians. Always consult the official Hitachi service manual for your specific serial number range and follow proper lockout/tagout procedures. If unfamiliar with high-voltage electrical systems or diagnostic procedures, consult a certified Hitachi dealer or qualified heavy equipment electrician to prevent equipment damage or personal injury.