What is Hitachi ZX890LCH-5A Fault Code 14104-2?

Fault Code 14104-2 on the Hitachi ZX890LCH-5A indicates an abnormal voltage signal (low voltage or open circuit) in the engine coolant temperature sensor circuit. This diagnostic trouble code (DTC) is triggered when the Engine Control Module (ECM) detects that the coolant temperature sensor is reading outside the normal operating range, typically below 0.2 volts or showing an open circuit condition.

The coolant temperature sensor is critical for this Isuzu-powered excavator because it directly influences fuel injection timing, engine warm-up protocols, and protection against overheating. When this sensor fails or provides incorrect data, the ECM cannot properly manage engine performance, potentially leading to hard starting, excessive fuel consumption, or inadequate engine protection during operation.

Common Symptoms

Operators of used ZX890LCH-5A excavators may experience the following when Code 14104-2 is active:

• Check Engine Warning Light illuminated on the instrument cluster, potentially with reduced engine power
• Difficulty starting the engine, especially in cold weather conditions, as the ECM defaults to a cold-start mode
• Rough idling or irregular engine performance during the warm-up phase
• Cooling fan running continuously at high speed, regardless of actual engine temperature
• Black smoke from exhaust due to overly rich fuel mixture from incorrect temperature compensation

Potential Causes

The most common technical causes for Code 14104-2 on used Hitachi excavators include:

• Faulty coolant temperature sensor due to internal element degradation (common after 5,000+ operating hours)
• Damaged or corroded wiring harness between the sensor and ECM, particularly at the connector near the thermostat housing where heat cycling causes brittleness
• Poor electrical connections at the sensor connector due to corrosion from coolant leaks or moisture intrusion
• Broken or chafed wires along the engine harness routing points, especially where the harness contacts the engine block or frame
• ECM internal circuit failure (rare, but possible in high-hour machines with electrical system history)

How to Troubleshoot and Fix Code 14104-2

Step 1: Visual Inspection Begin by inspecting the coolant temperature sensor located on the engine block near the thermostat housing. Check for coolant leaks, corrosion on the connector terminals, and physical damage to the wiring harness. On used excavators, pay special attention to areas where the harness may rub against the engine or frame components.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor and measure resistance across the sensor terminals. At 68°F (20°C), resistance should typically read 2,000-3,000 ohms (consult service manual for exact specifications). Next, check for continuity in the wiring from the sensor connector to the ECM connector. Measure voltage supply from the ECM—you should see approximately 5 volts at the sensor connector with the key on, engine off.

Step 3: Component Replacement and Verification If the sensor resistance is out of specification or wiring shows high resistance (above 5 ohms) or open circuit, replace the faulty component. For used machines, consider replacing both the sensor and connector pigtail simultaneously to prevent repeat failures. After repairs, clear the fault code using Hitachi Dr.EX diagnostic software or compatible scan tool, and monitor for code recurrence during a complete heat cycle.

Disclaimer: This guide provides general troubleshooting information. Always consult the official Hitachi service manual for your specific machine serial number and consider professional diagnostic assistance for complex electrical issues.