What is Hitachi ZX210LCN-5B Fault Code 19904-3?

Fault Code 19904-3 on the Hitachi ZX210LCN-5B excavator indicates a communication error between the Engine Control Module (ECM) and the Hydraulic Pump Control System, specifically related to CAN bus data transmission failures. This diagnostic trouble code (DTC) is triggered when the machine's controller network detects irregular or interrupted signal exchanges between critical control units.

The CAN (Controller Area Network) bus serves as the communication backbone for the ZX210LCN-5B's integrated systems. When Code 19904-3 appears, the ECM cannot properly coordinate with the hydraulic pump's electronic control, potentially causing the excavator to enter a protective derate mode. This fault is particularly critical because it affects the synchronized operation between engine power output and hydraulic demand—essential for precise digging performance and fuel efficiency on this 21-ton class machine.

Common Symptoms

• Warning light activation on the instrument panel, often accompanied by reduced engine power
• Hydraulic system sluggishness or inconsistent boom/arm speed during operation
• Engine derating to protect components, limiting RPM to approximately 1,500-1,800 range
• Intermittent loss of swing function or delayed response in combined operations
• Error messages displayed on the multi-information monitor regarding communication faults

Potential Causes

The most frequent causes for Code 19904-3 on used ZX210LCN-5B excavators include:

• Corroded or damaged CAN bus connectors at the ECM or hydraulic pump controller (common on machines operating in high-moisture environments)
• Wiring harness abrasion where the main harness passes near the engine mount or swing bearing—a known rub point on this model series
• Faulty termination resistor on the CAN network (typically 120-ohm resistance required)
• ECM or pump controller software glitches requiring initialization reset
• Voltage irregularities from failing batteries or alternator issues affecting data transmission quality
• Physical damage to wiring from previous repair work or rodent intrusion in stored machines

How to Troubleshoot and Fix Code 19904-3

Step 1: Visual Inspection Begin with a thorough examination of all CAN bus wiring between the ECM (located near the battery box) and the hydraulic pump controller. Check for obvious damage, pinched wires, or corroded connectors. On used excavators, pay special attention to harness routing near moving parts and areas where previous repairs may have compromised protective sleeving.

Step 2: Electrical Testing Using a digital multimeter, measure CAN-High and CAN-Low voltage at the ECM connector with the key switch ON (engine OFF). You should observe approximately 2.5V on each line when idle. Check termination resistance between CAN-H and CAN-L terminals—should read 60 ohms with both terminators in place. Incorrect readings indicate open circuits or missing resistors.

Step 3: Connector Service Disconnect the main ECM harness connector and hydraulic controller connector. Inspect pins for corrosion (common on machines with 3,000+ hours). Clean with electrical contact cleaner and apply dielectric grease before reconnection. This simple maintenance step resolves approximately 40% of communication codes on older machines.

Step 4: Diagnostic Software Analysis Connect Hitachi Dr.EX diagnostic software (or compatible tool) to read live CAN bus traffic. Monitor data packet transmission rates between modules. Intermittent dropouts visible in the software often point to failing controllers rather than wiring issues.

Step 5: Component Replacement If diagnostics confirm controller failure, replace the faulty unit. For used excavators, verify replacement part compatibility—the ZX210LCN-5B has specific software versions that must match across the CAN network.

Disclaimer: This guide provides general troubleshooting information. Always consult the official Hitachi service manual for your specific machine serial number. Complex electrical diagnostics should be performed by certified technicians with proper diagnostic equipment to prevent further damage to electronic systems.