What is Kobelco SK135SR-2 Fault Code D062?

Fault Code D062 on the Kobelco SK135SR-2 excavator indicates a malfunction in the Engine Control Module (ECM) communication circuit, specifically a CAN (Controller Area Network) bus communication error between the engine controller and the machine's main control system. This diagnostic trouble code (DTC) signals that the ECM is unable to properly transmit or receive data packets across the CAN communication line, which is critical for coordinating engine performance, hydraulic systems, and operator display functions.

This fault is particularly critical on the SK135SR-2 because the integrated control architecture relies on constant digital communication between controllers. When CAN bus communication fails, the excavator's electronic systems cannot synchronize properly, leading to reduced performance, inconsistent hydraulic response, or complete operational shutdown. On used machines, degraded wiring insulation and connector corrosion are common culprits that disrupt this essential data highway.

Common Symptoms

• Warning lamp illumination on the instrument panel, often accompanied by an error message on the multi-information display
• Engine derating or operation in limp mode with reduced RPM and power output to protect systems
• Erratic hydraulic performance including inconsistent swing speed, boom response delays, or intermittent loss of control functions
• Intermittent stalling or difficulty restarting the engine, especially after the machine warms up
• Complete loss of dashboard display functions or frozen gauges while the engine continues running

Potential Causes

The most common technical causes for Code D062 on used SK135SR-2 excavators include:

• Damaged or corroded CAN bus wiring harness, particularly at flex points near the engine mount or chassis frame where vibration causes wire chafing
• Faulty ECM connectors with bent pins, moisture intrusion, or green corrosion on terminal contacts (common after 3,000+ operating hours)
• Terminated resistor failure at either end of the CAN network, causing signal reflection and data corruption
• ECM internal failure or corrupted firmware, though less common than harness issues on older machines
• Voltage irregularities from weak batteries, failing alternators, or poor ground connections affecting the 12V/24V supply to communication circuits
• Aftermarket component interference from improperly installed monitoring systems or non-OEM electronic accessories

How to Troubleshoot and Fix Code D062

Step 1: Visual Harness Inspection Begin with a thorough physical examination of the CAN bus wiring harness running from the ECM (located near the engine) to the main controller. On used excavators, focus on areas where the harness passes through metal brackets, bends around the engine block, or routes near hot exhaust components. Look for abraded insulation, melted wire jackets, or pinched conductors. Check all connector boots for cracks that allow moisture entry.

Step 2: Connector and Terminal Testing Disconnect the main ECM connector and inspect all pins for corrosion, bent contacts, or heat damage. Use electrical contact cleaner and a brass brush to clean terminals showing oxidation. Using a digital multimeter, verify continuity on the CAN-High and CAN-Low signal wires (typically twisted pair, often yellow and green on Kobelco systems) from the ECM through to the main controller—resistance should read less than 5 ohms for good connections.

Step 3: Termination Resistor Verification The CAN network requires 120-ohm terminating resistors at both network endpoints. With all controllers disconnected, measure resistance between CAN-High and CAN-Low wires—you should read approximately 60 ohms (two 120-ohm resistors in parallel). Incorrect readings indicate a failed terminator or short circuit.

Step 4: Voltage and Ground Testing Check that the ECM receives stable power supply (12V or 24V depending on system configuration) using your multimeter at the power pins with ignition on. Verify less than 0.5V drop between ECM ground and battery negative terminal. Poor grounding is extremely common on used machines with corroded chassis ground points.

Step 5: Advanced Diagnostics with Kobelco PSSR Software If physical checks pass, connect Kobelco's PSSR (Parts and Service Sales Report) diagnostic software or compatible J1939 scanner tool to monitor live CAN bus traffic. Observe for missing message frames, excessive error counters, or specific controller drop-outs. This identifies whether the ECM, display controller, or other networked module is the source of communication failure.

Step 6: Component Replacement Protocol For used excavators, replace components in this priority: damaged harness sections first (repair with proper twisted-pair shielded cable and heat-shrink connections), corroded connectors second, terminating resistors third, and only replace the ECM as a last resort after confirming all wiring integrity. Always clear codes and perform multiple operational cycles to confirm permanent fixes versus intermittent issues.

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Disclaimer: This guide provides general troubleshooting information for experienced technicians. Always consult the official Kobelco service manual for your specific machine serial number, and consider professional diagnostic assistance for complex electrical issues. Improper repairs to electronic control systems can cause additional damage or safety hazards.