What is Kobelco SK140LC-8 Fault Code 20112?

Fault Code 20112 on the Kobelco SK140LC-8 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 main machine controller. This diagnostic trouble code (DTC) is triggered when the ECM detects an interruption, abnormal signal pattern, or complete loss of data transmission on the communication network that connects critical electronic systems.

This code is particularly critical for the SK140LC-8 because this model relies on integrated electronic controls to manage engine performance, hydraulic functions, and operator interface displays. When CAN bus communication fails, the excavator's electronic systems cannot properly coordinate, leading to reduced machine functionality, inaccurate monitoring, and potential safety concerns during operation.

Common Symptoms

When fault code 20112 is active on your Kobelco SK140LC-8, operators typically experience:

• Warning lights illuminating on the instrument panel, including the check engine light and potentially the master caution indicator
• Loss of monitor display functions, such as engine hours, coolant temperature, or hydraulic oil temperature readings showing incorrect or blank values
• Engine derating or limiting to reduced RPM as a protective measure when system communication is compromised
• Intermittent loss of throttle response or erratic engine behavior during operation
• Error messages appearing on the multi-function display indicating communication faults

Potential Causes

The most common technical causes for code 20112 on used SK140LC-8 excavators include:

• Damaged or corroded CAN bus wiring harness, particularly at known rub points near the engine mounting area and along the right side of the upper frame where harnesses route through tight spaces
• Loose or corroded electrical connectors at the ECM, main controller, or junction points throughout the communication network
• Failed termination resistors within the CAN bus network causing signal reflection and data corruption
• ECM internal failure or corrupted software requiring reprogramming or module replacement
• Voltage irregularities from failing batteries, alternator issues, or poor grounding connections affecting network stability
• Water intrusion into connector housings, especially common in machines operating in wet conditions or stored outdoors

How to Troubleshoot and Fix Code 20112

Step 1: Visual Inspection and Connector Check Begin by thoroughly inspecting all wiring harnesses along the CAN bus network route. Focus on areas where harnesses pass near moving components, sharp edges, or high-heat zones around the engine. Check all connector pins at the ECM (located behind the operator cab near the hydraulic tank) and the main controller module for corrosion, bent pins, or moisture. Clean connectors with electrical contact cleaner and ensure positive locking engagement.

Step 2: Electrical Testing of CAN Bus Network Using a digital multimeter (DMM), verify CAN-High and CAN-Low voltage signals at the ECM connector. With ignition on and engine off, you should measure approximately 2.5V on each line. Measure resistance between CAN-High and CAN-Low terminals; you should read approximately 60 ohms, indicating proper termination resistors are present. Values significantly higher suggest open circuits or failed terminators; lower values indicate short circuits.

Step 3: Harness Continuity and Isolation Testing Disconnect both the engine ECM and main controller connectors. Test continuity of CAN-High and CAN-Low wires individually from end to end—each should show less than 1 ohm resistance. Then test isolation: measure resistance from each CAN wire to chassis ground—readings should exceed 10,000 ohms. Lower readings indicate insulation breakdown or harness damage requiring replacement.

Step 4: Ground Circuit Verification Poor grounding is frequently overlooked in used machinery. Locate the primary ECM ground point (typically on the engine block) and the main controller ground on the frame. Remove, clean with a wire brush, and re-torque these connections. Verify less than 0.1 ohm resistance between ground points and battery negative terminal.

Step 5: Software and ECM Diagnostics Connect Kobelco diagnostic software (KPMS - Kobelco Parts Management System) via the diagnostic port. Review stored fault codes and freeze frame data to determine if the fault is current or historical. Check ECM software version and update if necessary. Monitor live CAN bus data during operation to identify intermittent communication dropouts that suggest vibration-related connector issues rather than hard failures.

For used excavators specifically, remember that connector degradation and harness chafing are the most common culprits. Before replacing expensive components like the ECM ($1,500-$2,500), invest time in thorough harness inspection and connector maintenance. Many communication faults on older SK140LC-8 models resolve with proper cleaning and securing of existing wiring.

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 engaging a certified Kobelco technician for complex electrical diagnostics to avoid damaging sensitive electronic components.