What is Hitachi ZX210LC-5G-HCMC Fault Code 16605-2?

Fault Code 16605-2 indicates a malfunction in the Engine Control Module (ECM) communication circuit, specifically a data link error between the ECM and the machine's main controller or display panel. This diagnostic trouble code (DTC) is triggered when the ECM detects an intermittent or complete loss of CAN bus communication on the J1939 network protocol used in Hitachi's HCMC (Hydraulic, Cooling, Monitoring, and Control) system architecture.

This fault is critical for the ZX210LC-5G because the ECM relies on continuous data exchange to coordinate engine performance with hydraulic demand, monitor emissions systems, and relay operational parameters to the operator display. When communication breaks down, the machine may enter a protective derate mode or fail to provide accurate diagnostics, compromising both productivity and preventive maintenance capabilities.

Common Symptoms

• Warning light illumination on the instrument cluster, often accompanied by a communication error message on the LCD display
• Intermittent loss of gauge readings including engine RPM, coolant temperature, or fuel level indicators going blank or freezing
• Reduced engine power or automatic derate to idle speed as a failsafe protection measure
• Inability to read live data or additional fault codes using diagnostic software due to communication interruption
• Erratic behavior of engine-dependent systems like auto-idle or engine shutdown timers

Potential Causes

The most common technical causes for Code 16605-2 on used ZX210LC-5G excavators include:

• Corroded or loose connectors at the ECM harness plug (C101) or main controller connector, particularly common in machines operating in wet or coastal environments
• Damaged CAN bus wiring due to harness chafing against the engine block or frame rails near the battery box area—a known wear point on this model
• Failed termination resistors on either end of the CAN network causing signal reflection and data corruption
• ECM internal communication port failure from voltage spikes or water intrusion through compromised seals
• Corroded ground points (G102 engine ground stud) affecting signal reference voltage on older machines with 5,000+ operating hours

How to Troubleshoot and Fix Code 16605-2

Step 1: Visual Inspection Begin by inspecting all wiring harness connections between the ECM (located under the right-side access panel) and the main controller. Look specifically for green corrosion on pins, bent terminals, or moisture inside connector boots. On used excavators, pay special attention to harness routing near the engine mounts where vibration causes insulation wear.

Step 2: Electrical Testing Using a digital multimeter, check for proper CAN-High and CAN-Low voltage at the ECM connector. With ignition on and engine off, you should measure approximately 2.5V on CAN-High (typically pin 27) and 2.5V on CAN-Low (typically pin 42) relative to ground. Measure termination resistance across CAN-High and CAN-Low with all power disconnected—you should read approximately 60 ohms if both 120-ohm terminating resistors are functioning correctly.

Step 3: Connector Service and Software Diagnosis Clean all connectors with electrical contact cleaner and apply dielectric grease to prevent future corrosion. Reconnect and use Hitachi Dr.EX diagnostic software to monitor live CAN bus traffic and verify bidirectional communication. If communication is restored, perform a wiggle test on harnesses while monitoring data to identify intermittent connection points common in high-hour used machines.

Step 4: Component Replacement If testing reveals harness damage, repair or replace the affected engine harness section rather than the entire loom to reduce costs on used equipment. Replace the ECM only after confirming power supply, grounds, and all wiring integrity, as ECM failure is relatively rare compared to connection issues.

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Disclaimer: This guide provides general troubleshooting information for experienced technicians. Always consult the official Hitachi service manual for your specific machine serial number and torque specifications. If unfamiliar with electrical diagnostics or CAN bus systems, seek assistance from a certified Hitachi dealer or qualified heavy equipment technician to avoid damaging expensive electronic components.