Sumitomo SH350HD-5 Fault Code 606: Complete Diagnostic Guide

What is Sumitomo SH350HD-5 Fault Code 606?

Fault Code 606 on the Sumitomo SH350HD-5 excavator indicates a malfunction in the Engine Control Module (ECM) communication circuit, specifically a loss of signal or intermittent connection between the ECM and the main machine controller. This code triggers when the CAN bus communication network fails to transmit critical data between the engine management system and the hydraulic control systems.

This fault is particularly critical on the SH350HD-5 because this model relies on integrated electronic communication between the Isuzu engine ECM and the Sumitomo proprietary hydraulic controller to optimize fuel efficiency and coordinate power delivery. When Code 606 appears, the machine may enter a protective derate mode or experience erratic performance as the systems cannot properly synchronize operations.

Common Symptoms

When Code 606 is active on your SH350HD-5, operators typically experience:

• Warning light illumination on the instrument cluster with possible audible alarm
• Sudden power loss or engine derate to reduced RPM (typically limiting to 1,400-1,600 RPM)
• Erratic hydraulic response or delayed boom/arm movements due to desynchronized commands
• Intermittent stalling at idle or during load transitions
• Multiple fault codes appearing simultaneously as communication failures cascade through systems

Potential Causes

The most common technical reasons for Code 606 on used SH350HD-5 excavators include:

• Corroded or damaged CAN bus connectors at the ECM or main controller (extremely common on machines operating in wet/marine environments)
• Harness chafing or wire breakage at known rub points near the engine mount brackets or along the right-hand chassis rail
• Failing ECM relay or intermittent power supply to the engine controller
• Degraded twisted-pair CAN wiring showing resistance values outside specification (should be 60 ohms across terminals)
• ECM internal failure (less common but possible on high-hour machines exceeding 8,000+ hours)
• Voltage irregularities from aging battery banks or failing alternator causing communication dropouts

How to Troubleshoot and Fix Code 606

Step 1: Visual Inspection and Connector Check Begin by inspecting all ECM connectors (located on the right side of the engine block) and the main controller harness behind the operator cab. On used excavators, check specifically for green corrosion, bent pins, or moisture intrusion in connector boots. Clean all contacts with electrical contact cleaner and apply dielectric grease.

Step 2: CAN Bus Resistance Testing Using a digital multimeter, disconnect both ends of the CAN communication line and measure resistance between CAN-High and CAN-Low terminals. You should read approximately 60 ohms. Readings significantly higher indicate wire damage; readings near zero suggest a short circuit requiring harness replacement.

Step 3: Voltage Supply Verification With the key in the ON position (engine off), verify the ECM receives stable 24V power supply at the main power connector. Check both battery voltage at rest (should be 24-26V) and voltage under cranking (shouldn't drop below 20V). Replace batteries or alternator if voltage is unstable.

Step 4: Diagnostic Software Analysis Connect Sumitomo-compatible diagnostic software (or universal tools like Jaltest) to read live data streams. Monitor CAN bus traffic and check for communication interruptions. Compare message frame rates against factory specifications to identify intermittent failures.

Step 5: Harness Routing Inspection (Critical for Used Machines) Trace the entire CAN harness routing from ECM to controller, paying special attention to areas where the harness passes near moving components or sharp edges. The SH350HD-5 has a known wear point where the harness contacts the engine mount during振动. Reroute or add protective sleeving as needed.

Disclaimer: This guide provides general troubleshooting procedures. Always consult the official Sumitomo service manual for your specific machine serial number and consider professional diagnostic assistance for complex electrical issues. Improper repairs to CAN bus systems can cause cascading failures across multiple machine control systems.