Hitachi ZX210LCN-5B Fault Code 19905-4: Expert Diagnostic Guide

What is Hitachi ZX210LCN-5B Fault Code 19905-4?

Fault Code 19905-4 indicates a communication error between the Engine Control Module (ECM) and the Hydraulic Pump Control System, specifically a CAN bus data transmission failure or timeout condition. This code signals that the engine controller cannot properly receive or send critical operational data to the hydraulic system's electronic control unit.

In the ZX210LCN-5B, this communication link is essential for coordinating engine speed with hydraulic pump output, ensuring optimal fuel efficiency and preventing over-revving during heavy lifting operations. When this CAN communication fails, the machine's integrated control system cannot balance power delivery between the engine and hydraulics, potentially causing performance degradation or complete system shutdown. This is particularly critical in used excavators where connector corrosion and wiring harness wear are common failure points.

Common Symptoms

• Yellow warning light illuminated on the instrument cluster with error message displayed on the monitor panel
• Significant loss of hydraulic power during simultaneous multi-function operations (boom and swing combined)
• Engine may enter derate mode, limiting RPM to approximately 1,500-1,800 to protect systems
• Intermittent or complete loss of fine control over attachment speed and precision
• Machine may experience delayed response when initiating hydraulic functions after idle periods

Potential Causes

The most frequent causes of Code 19905-4 on used ZX210LCN-5B excavators include:

• CAN bus wiring damage near the engine-to-chassis harness routing point (known wear location behind the hydraulic oil cooler)
• Corroded or moisture-infiltrated connector pins at the ECM or pump controller (18-pin Deutsch connector)
• Failed termination resistor on the CAN network (typically 120-ohm resistance)
• ECM internal communication circuit failure due to voltage spikes from jump-starting procedures
• Damaged or pinched shielded CAN cables in the swing post area where harnesses flex during rotation
• Software version mismatch between ECM and pump controller after component replacement in used machines

How to Troubleshoot and Fix Code 19905-4

Step 1: Visual Inspection of Harness and Connectors Begin by inspecting the main wiring harness routing from the ECM (located behind the operator's seat) to the hydraulic pump controller (mounted on the pump). Check for obvious abrasion points, particularly where harnesses contact metal edges near the engine mount. Disconnect the 18-pin Deutsch connector at both the ECM and pump controller; inspect pins for green corrosion, bent contacts, or moisture. Clean with electrical contact cleaner and apply dielectric grease before reconnecting.

Step 2: CAN Bus Integrity Testing Using a digital multimeter, measure resistance between CAN-High and CAN-Low terminals with all connectors disconnected and ignition off. You should read approximately 60 ohms (two 120-ohm termination resistors in parallel). If reading is infinite, locate the open circuit in the wiring. Check voltage with ignition on: CAN-High should read 2.5-3.5V, and CAN-Low should read 1.5-2.5V relative to chassis ground.

Step 3: Software and Controller Verification Connect Hitachi Dr.EX diagnostic software to verify both ECM and pump controller software versions are compatible (consult service bulletin for your specific serial number range). Clear codes and monitor live data stream while operating hydraulics. If code returns immediately, substitute a known-good ECM or pump controller to isolate the failed component. For used excavators, always verify the replacement parts came from the same model year range to avoid firmware incompatibility issues.

Professional Disclaimer: This diagnostic guide provides general troubleshooting procedures. Complex electrical issues may require factory-level diagnostic equipment and certified technician expertise. Always consult the official Hitachi service manual for your specific serial number and consider professional diagnosis for persistent communication faults.