Sumitomo SH260LC-6 Fault Code 1113: Complete Diagnostic Guide

What is Sumitomo SH260LC-6 Fault Code 1113?

Fault Code 1113 on the Sumitomo SH260LC-6 indicates an Engine Coolant Temperature (ECT) Sensor Circuit High Voltage condition. This diagnostic trouble code (DTC) is triggered when the Engine Control Module (ECM) detects an abnormally high voltage signal from the coolant temperature sensor, typically exceeding the normal operating range of 4.5-4.9 volts.

The ECT sensor plays a critical role in the SH260LC-6's engine management system by monitoring coolant temperature and relaying this data to the ECM. This information directly affects fuel injection timing, idle speed control, and engine protection protocols. When Code 1113 appears, the ECM may default to a preset temperature value, potentially causing improper engine operation and reduced fuel efficiency.

Common Symptoms

When Code 1113 is active on your Sumitomo SH260LC-6, operators typically experience:

• Engine warning light or check engine light illuminated on the instrument cluster
• Hard starting conditions, especially when the engine is cold
• Rough idle or irregular engine RPM fluctuations during warm-up
• Black smoke from exhaust due to incorrect fuel mixture calculations
• Engine derate mode or reduced power output as a protective measure
• Cooling fan running continuously at high speed regardless of actual engine temperature

Potential Causes

The following are the most common technical failures triggering Code 1113 in used Sumitomo excavators:

• Open circuit in ECT sensor wiring harness caused by wire breakage or connector damage
• Failed coolant temperature sensor with internal resistance breakdown (common after 5,000+ operating hours)
• Corroded or loose connector terminals at the sensor or ECM connection points
• Damaged sensor wiring from rubbing against engine components near the thermostat housing
• ECM internal fault affecting the sensor input circuit (rare but possible in high-hour machines)
• Poor ground connection on the sensor circuit return path
• Aftermarket sensor incompatibility if previous repairs used non-OEM parts

How to Troubleshoot and Fix Code 1113

Step 1: Visual Inspection Begin with a thorough inspection of the ECT sensor located near the thermostat housing on the engine block. Check for physical damage, coolant leaks around the sensor base, and examine the wiring harness for abrasion, cuts, or heat damage. On used excavators, pay particular attention to areas where the harness routes near moving components or sharp edges—a common failure point on the SH260LC-6.

Step 2: Connector and Resistance Testing Disconnect the ECT sensor connector and inspect both male and female terminals for corrosion, bent pins, or moisture intrusion. Using a digital multimeter, measure the sensor's resistance across its terminals. At room temperature (68°F/20°C), resistance should read approximately 2,000-3,000 ohms. Compare your reading against Sumitomo's specification chart for temperature-to-resistance values.

Step 3: Circuit Voltage Testing 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 near battery voltage (12V+), this confirms a high voltage condition and indicates either an open ground circuit or internal ECM fault.

Step 4: Harness Continuity Check Test continuity between the sensor connector and ECM pins using the machine's wiring diagram. Check for shorts to power, shorts to ground, and verify ground circuit integrity. For used machines with 8,000+ hours, replace any harness sections showing resistance above 5 ohms or signs of insulation breakdown.

Step 5: Component Replacement If testing confirms sensor failure, replace with a genuine Sumitomo ECT sensor or verified OEM-equivalent part. After installation, clear the fault code using diagnostic software and monitor for code recurrence during a complete heat cycle.

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Professional Disclaimer: This guide provides general diagnostic procedures for Code 1113. Always consult the official Sumitomo service manual for your specific machine serial number and software version. If you're uncomfortable performing electrical diagnostics on used heavy equipment, contact a certified Sumitomo technician or qualified diesel mechanic to prevent further damage to the ECM or engine management system.