Sumitomo SH480HD-6 Fault Code 113: Complete Diagnostic Guide

What is Sumitomo SH480HD-6 Fault Code 113?

Fault Code 113 on the Sumitomo SH480HD-6 excavator indicates an Engine Coolant Temperature (ECT) Sensor Circuit malfunction, specifically a high voltage condition or open circuit detected by the Engine Control Module (ECM). This code triggers when the ECM receives a voltage signal outside the normal operating range (typically above 4.5 volts), suggesting the sensor circuit is compromised.

The ECT sensor plays a critical role in the SH480HD-6's Isuzu engine management system by monitoring coolant temperature and adjusting fuel injection timing, idle speed, and emission controls accordingly. When this sensor circuit fails, the ECM defaults to a predetermined temperature value, which can lead to inefficient engine operation, increased fuel consumption, and potential overheating risks on this heavy-duty excavator platform.

Common Symptoms

When Code 113 is active on your SH480HD-6, operators typically experience:

• Engine warning light illuminated on the instrument cluster (amber or red depending on severity)
• Hard starting conditions, especially when the engine is cold, due to improper fuel mapping
• Rough idle or engine surging as the ECM compensates with default temperature values
• Cooling fan running continuously at high speed, regardless of actual engine temperature
• Reduced engine power or derate mode activation in some cases to protect engine components

Potential Causes

The most common technical failures causing Code 113 on used SH480HD-6 excavators include:

• Open circuit in the ECT sensor wiring harness, particularly where the harness routes near the engine block and experiences thermal cycling
• Corroded or damaged connector pins at the ECT sensor plug—a frequent issue on machines operating in wet or corrosive environments
• Failed ECT sensor with internal open circuit (less common but possible after 5,000+ operating hours)
• Chafed wiring at known rub points near the engine mount brackets or valve cover
• Poor ground connection at the sensor circuit return path to the ECM

How to Troubleshoot and Fix Code 113

Step 1: Visual Inspection Begin by locating the ECT sensor on the engine block (typically near the thermostat housing on Isuzu engines). Inspect the sensor connector for corrosion, moisture intrusion, or bent pins. On used excavators, check the wiring harness for abrasion points where it contacts metal surfaces—this is critical on older machines with brittle insulation.

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

Step 3: Circuit Voltage Check With the sensor disconnected and ignition ON (engine OFF), measure voltage at the ECM-side connector. You should see approximately 5 volts reference voltage from the ECM. If voltage reads above 4.8 volts continuously, inspect the signal wire for breaks or the ground wire for poor connections.

Step 4: Harness Continuity Test Check continuity between the sensor connector and ECM pins (refer to wiring diagrams). Pay special attention to the ground circuit—corroded grounds are common on used machines. Repair or replace damaged sections of the harness, ensuring proper routing away from heat sources.

Step 5: Clear Code and Verify After repairs, clear the fault code using diagnostic software or by disconnecting the battery for 5 minutes. Monitor the system during a complete heat cycle to ensure the code does not return.

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Disclaimer: This guide provides general diagnostic procedures for Code 113. Always consult the official Sumitomo service manual for your specific machine serial number. If you're uncomfortable performing electrical diagnostics, contact a certified Sumitomo technician to prevent further damage to the ECM or wiring systems.