Sumitomo SH380LHD-6 Fault Code 1113: Complete Diagnostic Guide

What is Sumitomo SH380LHD-6 Fault Code 1113?

Fault Code 1113 on the Sumitomo SH380LHD-6 indicates a malfunction in the Engine Coolant Temperature (ECT) sensor circuit, specifically detecting an abnormally high voltage signal or open circuit condition. This code triggers when the Engine Control Module (ECM) receives voltage readings outside the normal operating range (typically above 4.5V) from the coolant temperature sensor.

The ECT sensor is critical for this excavator's performance because it directly influences fuel injection timing, engine warm-up protocols, and cooling fan activation. When this sensor fails or sends incorrect data, the ECM cannot properly regulate engine temperature, potentially leading to overheating, poor fuel economy, and reduced hydraulic system efficiency on the SH380LHD-6.

Common Symptoms

• Check Engine Light or engine warning lamp illuminated on the instrument cluster
• Engine runs in cold start mode continuously, resulting in rough idle and black exhaust smoke
• Cooling fan runs constantly at high speed, even when engine temperature is normal
• Reduced engine power or derate mode activation during heavy excavation work
• Difficulty starting in cold weather conditions due to improper fuel mixture compensation

Potential Causes

The most common technical failures causing Code 1113 on used Sumitomo excavators include:

• Open circuit in the ECT sensor wiring harness, often caused by vibration damage near the engine mounting points
• Failed coolant temperature sensor due to corrosion or internal element degradation (common after 8,000+ operating hours)
• Damaged or corroded connector pins at the sensor or ECM connection points
• Wiring harness chafing against the engine block or hydraulic lines—a known wear point on the SH380LHD-6 near the thermostat housing
• ECM internal circuit failure (rare, but possible in high-hour machines with electrical system history)

How to Troubleshoot and Fix Code 1113

Step 1: Visual Inspection Begin by inspecting the ECT sensor located near the thermostat housing on the engine block. Check for damaged wiring, corroded connector terminals, or coolant leaks that may have contaminated the electrical connection. On used excavators, pay special attention to harness routing where it contacts metal surfaces.

Step 2: Electrical Testing Using a digital multimeter, disconnect the ECT sensor connector and measure resistance across the sensor terminals. At 68°F (20°C), resistance should read approximately 2,500-3,000 ohms (consult your service manual for exact specifications). If the reading shows infinite resistance (open circuit) or zero resistance (short circuit), replace the sensor.

Step 3: Wiring Harness Verification With the sensor disconnected, measure voltage at the ECM-side connector. You should see approximately 5V reference voltage. Check continuity between the sensor connector and ECM pins to identify any breaks in the wiring. Inspect the harness for wear points, especially where it passes over the engine valve cover.

Step 4: Clear Code and Test After repairs, clear the fault code using Sumitomo diagnostic software or a compatible scanner. Run the engine through a complete heat cycle and monitor for code recurrence.

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Disclaimer: This guide provides general diagnostic procedures. Always consult the official Sumitomo service manual for your specific machine serial number. If you lack proper diagnostic tools or experience with high-voltage electrical systems, consult a certified heavy equipment technician to prevent injury or further damage.