What is Kobelco SK140LC-8 Fault Code 16711?

Fault Code 16711 on the Kobelco SK140LC-8 excavator indicates a communication error between the Engine Control Module (ECM) and the Machine Control Module (MCM), specifically a CAN bus communication fault. This diagnostic trouble code (DTC) means the two critical control systems are not exchanging data properly through the Controller Area Network (CAN) data link.

This code is particularly serious because the ECM and MCM must constantly communicate to coordinate engine performance with hydraulic demands, monitor system health, and protect the machine from damage. When communication breaks down, the excavator's integrated control system cannot function as designed, potentially leading to reduced performance, unexpected shutdowns, or the machine entering a protective derate mode. For used Kobelco SK140LC-8 excavators, this fault often stems from aging electrical components or previous repairs that may have compromised the CAN bus wiring harness integrity.

Common Symptoms

When Code 16711 is active, operators typically experience:

• Warning lights illuminated on the instrument panel, often including check engine or system malfunction indicators
• Loss of communication between display monitors, showing incomplete or frozen data
• Engine derating or limited power output as the ECM enters a protective failsafe mode
• Erratic hydraulic response or inconsistent performance due to lack of coordinated control
• Intermittent machine shutdowns or inability to start, particularly after the machine has warmed up

Potential Causes

The most common technical causes for Code 16711 in used SK140LC-8 excavators include:

• Damaged or corroded CAN bus wiring harness connections, especially at connector pins prone to moisture intrusion
• Loose or disconnected ground connections affecting the communication circuit reference voltage
• Failed termination resistors on the CAN bus network (typically 120-ohm resistors at each network end)
• ECM or MCM internal failure, though less common than wiring issues in used machines
• Harness chafing at known wear points, particularly where cables route near moving components or sharp metal edges
• Previous repair attempts that introduced wiring splices, aftermarket connectors, or improper routing
• Voltage supply issues to either control module affecting their ability to communicate

How to Troubleshoot and Fix Code 16711

Step 1: Visual Inspection of CAN Bus Connections

Begin with a thorough physical inspection of all wiring harnesses between the ECM and MCM. On used excavators, pay particular attention to connector housings for corrosion, moisture, or bent pins. Check the main CAN-H and CAN-L twisted pair wires (typically yellow and green) for physical damage, especially where they pass through bulkheads or near the swing bearing. Inspect all ground connections for tightness and corrosion—clean and secure as needed.

Step 2: Test CAN Bus Integrity with Diagnostic Tools

Using a digital multimeter, measure the resistance between CAN-H and CAN-L terminals with both modules disconnected and ignition off. You should read approximately 60 ohms (two 120-ohm termination resistors in parallel). If you read infinite resistance, a termination resistor has failed or there's an open circuit. If resistance is below 50 ohms, there's likely a short or additional unintended ground path. Kobelco-specific diagnostic software (such as Dr.EX) provides the most precise testing, allowing you to monitor real-time communication packets and identify which module isn't responding.

Step 3: Check Module Power Supply and Grounds

Verify that both the ECM and MCM are receiving proper supply voltage (typically 24V on this machine). Check voltage at the module connectors with ignition on—it should match battery voltage. Test ground circuits for continuity and resistance (should be less than 0.5 ohms to chassis ground). For used machines, clean all ground terminals with a wire brush and apply dielectric grease to prevent future corrosion.

Step 4: Replace Components Systematically

If all electrical tests pass but the code persists, suspect internal module failure. Before replacing expensive control modules on a used excavator, consider swapping the CAN bus termination resistors (inexpensive components that fail more frequently). If replacing harnesses, ensure proper routing away from heat sources and use OEM-quality connectors with proper sealing. Always clear codes and test thoroughly after each repair to confirm which intervention resolved the issue.

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Disclaimer: This guide provides general troubleshooting information for educational purposes. 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 control systems can result in further damage or safety hazards.