What is Hitachi ZX210LCK-5G Fault Code 20105-2?

Fault Code 20105-2 on the Hitachi ZX210LCK-5G excavator indicates a malfunction in the Engine Control Module (ECM) communication circuit, specifically a CAN bus communication error between the engine controller and the main machine controller. This code triggers when the ECM detects an interruption, voltage irregularity, or complete loss of data transmission on the Controller Area Network (CAN) system.

The CAN bus serves as the central nervous system for this excavator model, enabling real-time communication between the engine management system, hydraulic controllers, and display monitor. When communication fails, the machine's integrated control systems cannot coordinate properly, leading to reduced performance or complete operational shutdown. For the ZX210LCK-5G's Isuzu engine platform, maintaining proper ECM communication is critical for emissions compliance, fuel efficiency, and preventing costly engine damage from unmonitored operating conditions.

Common Symptoms

• Warning lights: Engine malfunction lamp illuminated on the dash; possible simultaneous hydraulic system warnings
• Derating or limp mode: Engine power significantly reduced to 40-60% capacity; hydraulic functions may operate at reduced speed
• Intermittent shutdowns: Machine may start normally but shut down unexpectedly after 5-30 minutes of operation
• Display errors: Monitor screen showing "Communication Error" or complete loss of engine parameter readings (RPM, temperature, pressure)
• Erratic performance: Inconsistent throttle response or hydraulic function delays due to controller coordination failure

Potential Causes

Wiring harness damage is the primary culprit in used ZX210LCK-5G excavators, particularly where the main harness routes near the swing bearing or along the boom base—these are known friction points. CAN bus termination resistor failure occurs when resistors at either end of the network degrade, causing signal reflection and data corruption.

Corroded or loose connectors at the ECM or main controller, especially the 38-pin ECM connector behind the cab, frequently cause intermittent communication loss on machines with 5,000+ hours. ECM or main controller failure is less common but possible, particularly in machines exposed to water intrusion or voltage spikes from jump-starting procedures. Aftermarket component interference, such as non-OEM monitors or telematics devices improperly wired into the CAN network, can also trigger this code.

How to Troubleshoot and Fix Code 20105-2

Step 1: Visual Inspection and Connector Check Begin by inspecting the main wiring harness from the ECM (located under the operator's seat or behind the right-side panel) to the main controller. Look specifically for chafing where the harness crosses the swing post and near hydraulic line routing. Remove and inspect the 38-pin ECM connector and corresponding main controller connector for corrosion, bent pins, or moisture intrusion—clean with electrical contact cleaner and apply dielectric grease.

Step 2: CAN Bus Voltage and Resistance Testing Using a digital multimeter, measure resistance between CAN-High and CAN-Low terminals at the ECM connector with the key off and all controllers disconnected. You should read approximately 60 ohms, indicating proper termination resistors. With the key on (engine off), measure voltage on CAN-High (should read 2.5-3.5V) and CAN-Low (should read 1.5-2.5V). Readings outside these ranges indicate termination resistor failure or wiring short/open circuits.

Step 3: Diagnostic Software Analysis Connect Hitachi Dr.EX diagnostic software or compatible scan tool to the machine's diagnostic port. Monitor live CAN bus traffic and check for communication dropouts or error frame counts. Compare communication status between ECM, main controller, and display module. If one controller shows "No Response," isolate that circuit branch. For used excavators, this step often reveals previous repair attempts or non-standard wiring modifications.

Step 4: Component Isolation and Replacement If wiring and connections test normal, systematically disconnect aftermarket accessories (GPS, cameras, telematics) to identify interference sources. Replace termination resistors (typically 120-ohm, ¼ watt) at network endpoints if resistance testing failed. On high-hour machines, consider replacing the entire engine-to-chassis harness section if multiple rub-through points exist—this prevents recurring failures. ECM or controller replacement should be the last resort after all wiring and termination issues are eliminated.

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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 software version. Improper diagnosis can lead to unnecessary parts replacement or additional damage. When working with electrical systems, disconnect batteries and follow proper lockout/tagout procedures. For complex ECM programming or CAN bus issues, contact a certified Hitachi dealer or qualified heavy equipment electronics specialist.