What is Hitachi ZX210LCN-5B Fault Code 19904-4?

Fault Code 19904-4 on the Hitachi ZX210LCN-5B indicates a communication error or data transmission failure within the machine's CAN (Controller Area Network) bus system, specifically related to the engine control module (ECM) or between networked controllers. This diagnostic trouble code (DTC) signals that one or more control units are not receiving or transmitting data packets correctly across the machine's internal network.

This code is critical for the ZX210LCN-5B because the CAN bus serves as the central nervous system, allowing the engine ECM, hydraulic controller, monitor display, and other modules to share operational data in real-time. When communication breaks down, the excavator cannot properly coordinate functions like fuel injection timing, hydraulic flow management, or error reporting, leading to degraded performance or complete operational shutdown.

Common Symptoms

• Warning lights illuminated on the operator display, often accompanied by communication error messages or system fault indicators
• Loss of monitor display functions, including inability to view engine parameters, fuel levels, or hydraulic temperatures
• Engine derate mode or reduced power output as the ECM enters failsafe operation due to missing sensor data
• Intermittent or complete shutdown of the machine, particularly during high-load operations when multiple controllers need coordinated communication
• Erratic hydraulic responses or sluggish implement movement caused by delayed command signals between controllers

Potential Causes

The most common technical causes for Code 19904-4 on used Hitachi excavators include:

• Corroded or damaged CAN bus connectors, particularly at junction points near the engine bay where moisture and vibration exposure is highest
• Fractured or chafed wiring harness along known rub points, especially where harnesses pass through the rotating house or near the boom pivot area
• Failed termination resistors at either end of the CAN network (typically 120-ohm resistors that prevent signal reflection)
• ECM power supply issues, including loose battery connections, corroded ground points, or voltage drops below the 9-volt minimum threshold
• Controller module failure in the ECM, monitor display, or secondary control units due to age-related component degradation in used machines

How to Troubleshoot and Fix Code 19904-4

Step 1: Visual Inspection of CAN Network Components Begin by thoroughly inspecting all CAN bus harness connectors throughout the machine. On used excavators, focus on the main harness routing from the engine ECM to the cab display, checking for green corrosion on pins, moisture intrusion in connector boots, or physical damage to connector bodies. Use electrical contact cleaner and verify all connections seat firmly with intact locking tabs.

Step 2: Check CAN Bus Termination and Continuity Using a digital multimeter, measure resistance across the CAN-High and CAN-Low wires at the diagnostic connector with the machine powered off. You should read approximately 60 ohms (two 120-ohm termination resistors in parallel). If the reading is open circuit (infinite resistance) or significantly different, locate and replace failed termination resistors or repair open circuits in the twisted-pair CAN wiring.

Step 3: Verify Power Supply to ECM Check battery voltage at the ECM connector with the key on—it should read 12-14 volts on diesel systems. Inspect both positive supply wires and, critically, the ground connections at the ECM mounting bracket. On used machines, corrosion between the ECM case and chassis ground can create intermittent communication failures. Clean all ground points to bare metal and apply dielectric grease.

Step 4: Scan with Hitachi Diagnostic Software Connect Dr.EX diagnostic software or an equivalent Hitachi-compatible scan tool to read live CAN bus communication status. Monitor which specific controllers are dropping offline or showing transmission errors. This identifies whether the fault originates from a specific module or a network-wide harness issue. Used excavators often exhibit intermittent faults that only appear under vibration, so perform a "wiggle test" on suspect connectors while monitoring live data.

Step 5: Replace Faulty Components If diagnostics isolate a specific failed control module, replacement is necessary. However, for used excavators with high operating hours, prioritize replacing deteriorated wiring harnesses and connectors before condemning expensive controllers. Many 19904-4 codes resolve after addressing corroded pins or worn harness insulation at high-flex areas.

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Disclaimer: This guide provides general troubleshooting information for educational purposes. Always consult the official Hitachi service manual for your specific machine serial number and consider professional diagnostic assistance for complex electrical issues. Improper repairs to networked control systems can cause additional fault codes or operational hazards.