Sumitomo SH210-6 Fault Code 604: Complete Diagnostic Guide

What is Sumitomo SH210-6 Fault Code 604?

Fault Code 604 on the Sumitomo SH210-6 excavator indicates a malfunction in the Engine Control Module (ECM) communication circuit or a failure in the controller area network (CAN) bus system. This code specifically signals that the main ECM has lost communication with critical control systems, preventing proper data exchange between the engine controller and hydraulic/electrical subsystems.

This communication failure is critical because the SH210-6 relies on continuous data flow between controllers to manage fuel injection timing, hydraulic pump output, and emission controls. When the CAN bus network fails, the machine may enter a protective derate mode or experience complete operational shutdown to prevent engine damage.

Common Symptoms

When Code 604 is active on your Sumitomo SH210-6, you may experience:

• Check Engine light or warning indicator illuminated on the instrument panel
• Sudden loss of engine power or the machine entering limp mode with restricted RPM
• Erratic hydraulic response or complete loss of auxiliary hydraulic functions
• Intermittent engine stalling, especially during high-load operations
• Inability to communicate with the machine using diagnostic software

Potential Causes

The most common technical causes for Code 604 on used SH210-6 excavators include:

• Corroded or damaged CAN bus wiring harness connections, particularly at the main harness junction near the battery box (a known wear point on this model)
• Failed ECM relay or blown fuse in the controller power supply circuit
• Water intrusion into ECM connectors causing short circuits or corrosion
• Defective ECM unit itself, often due to voltage spikes from battery disconnection or jump-starting
• Broken or frayed wiring at flex points near the engine mount or cab pivot areas
• Faulty ground connections at the frame grounding points

How to Troubleshoot and Fix Code 604

Step 1: Perform Visual Inspection Begin by inspecting all wiring harnesses connected to the ECM, located under the operator's cab. Check for visible damage, corrosion on connector pins, or moisture inside connector boots. On used excavators, pay special attention to harness routing where cables contact the frame or pass through grommets.

Step 2: Test Power Supply and Grounds Using a digital multimeter, verify that the ECM is receiving proper voltage (typically 24V on this model). Check battery voltage at the ECM connector with the key in the ON position. Test ground continuity between the ECM case and chassis ground—resistance should be less than 1 ohm.

Step 3: Check CAN Bus Integrity Measure resistance between CAN-High and CAN-Low terminals at the ECM connector (consult service manual for pin identification). Proper termination resistance should read approximately 60 ohms. Infinite resistance indicates an open circuit in the network; near-zero resistance suggests a short circuit.

Step 4: Inspect Relays and Fuses Locate the ECM power relay in the main fuse box and test for proper operation. Swap with an identical relay to rule out failure. Check all related fuses for hidden cracks or corrosion.

Step 5: Use Diagnostic Software Connect Sumitomo-compatible diagnostic software to read live data and verify which specific controller has lost communication. This pinpoints whether the issue is with the ECM, display panel, or another module on the network.

For used machines, always clean all connector contacts with electrical contact cleaner and apply dielectric grease before reassembly to prevent future corrosion issues.

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Disclaimer: This guide provides general troubleshooting information. Always consult the official Sumitomo service manual for your specific serial number and seek assistance from a certified heavy equipment technician for complex electrical diagnostics or ECM replacement.