Sumitomo SH380LHD-6 Fault Code 113: Complete Diagnostic Guide

What is Sumitomo SH380LHD-6 Fault Code 113?

Fault Code 113 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 diagnostic trouble code (DTC) is triggered when the Engine Control Module (ECM) receives a voltage reading above the manufacturer's specified threshold, typically exceeding 4.8 volts on a 5-volt reference circuit.

The ECT sensor plays a critical role in the SH380LHD-6's performance management system. It monitors coolant temperature to optimize fuel injection timing, throttle response, and engine protection protocols. When this sensor circuit fails, the ECM cannot accurately assess engine thermal status, potentially leading to inefficient combustion, increased emissions, and risk of overheating damage to this high-performance excavator's powerplant.

Common Symptoms

• Engine warning light illuminated on the instrument cluster with reduced engine power (derate mode)
• Hard starting conditions, particularly in cold weather, due to improper fuel enrichment
• Cooling fans running continuously at maximum speed regardless of actual engine temperature
• Erratic temperature gauge readings or gauge stuck at minimum position
• Black smoke from exhaust caused by overly rich fuel mixture from incorrect temperature compensation

Potential Causes

The most frequent causes of Code 113 on used SH380LHD-6 excavators include:

• Open circuit in ECT sensor wiring harness, commonly occurring where the harness routes near the engine block or passes through vibration-prone mounting points
• Failed ECT sensor with internal open circuit (common failure mode after 5,000+ operating hours)
• Corroded or damaged connector terminals at the sensor or ECM connection points—particularly susceptible in machines operating in coastal or high-humidity environments
• Chafed wiring where the harness contacts sharp metal edges near the thermostat housing
• ECM internal fault (rare, but possible in high-hour machines with electrical system stress)

How to Troubleshoot and Fix Code 113

Step 1: Visual Inspection Begin with the engine cool. Locate the ECT sensor (typically installed in the thermostat housing or cylinder head). Inspect the sensor connector for corrosion, pushed-back pins, or moisture intrusion. Check the wiring harness from sensor to ECM for obvious damage, particularly at harness routing points near engine mounts.

Step 2: Electrical Testing Disconnect the ECT sensor connector. Using a digital multimeter, measure resistance across the sensor terminals. At room temperature (20°C/68°F), resistance should read approximately 2,000-3,000 ohms (consult your service manual for exact specifications). Next, check for continuity between each sensor wire and ground—there should be infinite resistance (no continuity), indicating no short to ground.

Step 3: Circuit Voltage Check With the sensor disconnected and ignition ON (engine off), measure voltage at the ECM-side harness connector. You should see approximately 5 volts on the signal wire. If voltage reads above 4.9 volts continuously, this confirms the open circuit condition triggering Code 113.

Step 4: Repair or Replace For used excavators, thoroughly inspect connector terminals and apply dielectric grease to prevent future corrosion. Replace damaged wiring sections using OEM-specification wire and heat-shrink connectors. If the sensor tests faulty, install a genuine Sumitomo/Isuzu ECT sensor (the SH380LHD-6 uses an Isuzu engine platform). After repairs, clear codes using diagnostic software and monitor during a complete heat cycle.

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Disclaimer: This guide provides general diagnostic information. Always consult the official Sumitomo service manual for your specific machine serial number. If unfamiliar with electrical diagnostics, seek assistance from a certified heavy equipment technician to prevent damage to sensitive electronic components.