Sumitomo SH260LC-6 Fault Code 602: Complete Diagnostic Guide

What is Sumitomo SH260LC-6 Fault Code 602?

Fault Code 602 on the Sumitomo SH260LC-6 excavator indicates an Engine Controller (ECM) communication error or loss of signal between the main controller and the engine control unit. This code specifically points to a breakdown in the CAN bus communication network that allows the machine's electronic systems to exchange critical operational data.

This fault is particularly critical for the SH260LC-6 because it directly impacts the machine's ability to regulate engine performance, monitor vital parameters, and coordinate hydraulic system functions. When communication fails, the excavator's integrated systems cannot properly synchronize, leading to reduced efficiency and potential safety concerns. The ECM relies on constant data exchange to optimize fuel injection timing, throttle response, and emission controls specific to this model's Isuzu engine platform.

Common Symptoms

When Code 602 is active on your SH260LC-6, operators typically experience:

• Engine warning light illuminated on the instrument cluster, often accompanied by a check engine indicator
• Intermittent loss of power or engine entering a reduced performance (derate) mode to protect components
• Erratic gauge readings including inaccurate RPM, temperature, or pressure displays on the monitor panel
• Hydraulic system irregularities such as sluggish response or inconsistent swing/boom operation
• Engine stalling or difficulty restarting, particularly after the machine has been operating under load

Potential Causes

The most common technical reasons for Code 602 appearing on used SH260LC-6 excavators include:

• Corroded or loose CAN bus connectors at the ECM or main controller harness connections
• Damaged wiring harness particularly near the engine mounting points where vibration causes wire chafing
• Faulty ECM ground connections due to corrosion or loose mounting bolts
• Water intrusion into electrical connectors, common in machines with compromised cab sealing
• Failed ECM or main controller module, though less common than harness issues
• Aftermarket modifications or improper repairs that disrupted the communication network
• Battery voltage irregularities causing intermittent power supply to control modules

How to Troubleshoot and Fix Code 602

Step 1: Visual Inspection Begin with a thorough inspection of all wiring harnesses between the engine ECM (located near the engine) and the main controller. On used excavators, pay special attention to harness routing where it passes through the swing bearing area and along the engine firewall—these are known rub points on the SH260LC-6. Check all connector pins for corrosion, bent terminals, or moisture contamination.

Step 2: Test Communication Network Using a digital multimeter, verify proper voltage at the ECM power supply (should read 24V with key on). Check CAN High and CAN Low wire continuity between the ECM and main controller. Resistance should typically measure 60 ohms across the network when properly terminated. If available, connect Sumitomo diagnostic software (or compatible J1939 scanner) to read real-time communication status and identify which module is dropping offline.

Step 3: Ground Circuit Verification Inspect and clean all ECM ground points. Remove ground cables, wire-brush contact surfaces, and reinstall with proper torque specifications. Poor grounding is extremely common in older machines and often causes intermittent communication faults.

Step 4: Component Testing If wiring checks pass, test the ECM and main controller by swapping with known-good units if available. Before replacing expensive modules on used equipment, verify that all connector seals are intact and consider professional harness repair for damaged sections rather than complete replacement.

Disclaimer: This guide provides general diagnostic procedures. Always consult the official Sumitomo service manual for your specific machine serial number and consider professional diagnostic services for complex electrical issues. Improper repairs can cause additional damage to electronic components.