What is Hitachi ZX210K-5G-HCMC Fault Code 16605-2?

Fault Code 16605-2 indicates a malfunction in the Engine Control Module (ECM) communication circuit, specifically a CAN (Controller Area Network) bus communication error between the engine ECM and the machine's main controller. This diagnostic trouble code (DTC) signals that data transmission between critical control systems has been interrupted or degraded beyond acceptable parameters.

In the Hitachi ZX210K-5G-HCMC excavator, the CAN bus network serves as the central nervous system, allowing the engine ECM, hydraulic controller, and display monitor to share real-time operational data. When communication fails, the machine cannot properly coordinate engine performance with hydraulic demand, leading to reduced efficiency and potential safety concerns. This code is particularly critical because it affects the integrated control system that optimizes fuel consumption and power delivery across all machine functions.

Common Symptoms

• Warning light illumination on the instrument cluster, often accompanied by a check engine indicator or communication error icon
• Reduced engine power or derate mode activation, limiting machine performance to protect systems from uncoordinated operation
• Erratic hydraulic response or sluggish boom/arm movements due to loss of load-sensing communication
• Intermittent gauge failures on the monitor display, including loss of coolant temperature, fuel level, or hour meter readings
• Engine may run rough or fail to respond properly to throttle inputs during high-demand operations

Potential Causes

The most common technical causes for Code 16605-2 on used Hitachi excavators include:

• CAN bus wiring harness damage from rubbing against frame components, particularly near the engine mounting points where vibration is highest
• Corroded or loose connector pins at the ECM or main controller junction, especially on machines with high operating hours in wet or corrosive environments
• Failed termination resistors within the CAN network, which are essential for signal integrity on older machines
• ECM internal communication module failure, more common in excavators exceeding 8,000 operating hours
• Voltage supply issues to either the ECM or main controller, often caused by failing ground connections or battery cable deterioration
• Aftermarket component interference, such as non-OEM monitors or telematics devices improperly integrated into the CAN system

How to Troubleshoot and Fix Code 16605-2

Step 1: Visual Harness Inspection Begin with a thorough physical examination of the CAN bus wiring harness running from the engine compartment to the cab area. On used excavators, check for visible wear, abrasion, or pinch points where the harness routes near the engine mounts or through bulkhead penetrations. Pay special attention to connector boots for cracks or moisture intrusion.

Step 2: Connector and Pin Integrity Check Disconnect the main ECM connector and the machine controller connector. Inspect all pins for corrosion, bent contacts, or signs of overheating (discoloration). Use electrical contact cleaner and a fine brush to clean pins. Measure pin-to-pin resistance within connectors; any reading below 1 ohm between adjacent pins suggests contamination or moisture.

Step 3: CAN Bus Voltage and Resistance Testing Using a digital multimeter, measure the voltage on the CAN-High and CAN-Low wires with the key in the ON position (engine off). You should read approximately 2.5V on CAN-High and 2.5V on CAN-Low at rest. With the engine running, these values should fluctuate between 2.0-3.5V. Next, measure termination resistance across CAN-High and CAN-Low with all power disconnected; you should read approximately 60 ohms, indicating proper termination resistors are functioning.

Step 4: Diagnostic Software Scan Connect Hitachi Dr.EX diagnostic software or compatible scan tool to retrieve active and stored codes. Check for additional related codes that might indicate whether the issue originates from the engine ECM or machine controller side. Monitor live data stream during key-on and engine running to identify communication dropouts.

Step 5: Component Isolation Testing If harness and connections test properly, systematically disconnect non-essential CAN devices (aftermarket displays, telematics units) to identify if an aftermarket component is causing bus interference. For used machinery, this is a common overlooked issue when previous owners added monitoring equipment.

Step 6: ECM and Controller Evaluation If all wiring tests pass, the fault likely resides in either the engine ECM or main machine controller. Swap the ECM with a known-good unit if available, or consult with a Hitachi-certified technician for controller programming verification. On high-hour used excavators, internal ECM component failure becomes more probable.

Critical Note for Used Excavators: Before replacing expensive electronic modules, invest time in thorough harness inspection and connector refurbishment. Approximately 70% of CAN communication faults on used heavy equipment stem from physical wiring issues rather than failed electronics.

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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 engaging a certified technician for complex electrical diagnostics. Improper repairs may void warranties or create safety hazards.