Sumitomo SH360HD-6 Fault Code 1113: Complete Diagnostic Guide

What is Sumitomo SH360HD-6 Fault Code 1113?

Fault Code 1113 indicates an Engine Coolant Temperature (ECT) Sensor Circuit High Voltage condition in the Sumitomo SH360HD-6 excavator's electronic control system. This diagnostic trouble code (DTC) is triggered when the Engine Control Module (ECM) detects an abnormally high voltage reading from the coolant temperature sensor circuit, typically above 4.8-5.0 volts.

The ECT sensor plays a critical role in engine performance management by monitoring coolant temperature and sending voltage signals to the ECM. This data directly influences fuel injection timing, idle speed control, and engine protection strategies. On the SH360HD-6, this code can cause the engine to enter a derate mode or prevent cold-start enrichment, significantly impacting operational efficiency and potentially causing engine damage if ignored.

Common Symptoms

When Code 1113 is active on your SH360HD-6, operators typically experience:

• Engine warning lamp illuminated on the instrument cluster (amber or red depending on severity)
• Hard starting conditions, especially in cold weather, due to improper fuel mapping
• Rough idle or poor throttle response as the ECM defaults to failsafe temperature values
• Cooling fan running continuously at high speed regardless of actual engine temperature
• Power derate or reduced hydraulic performance as the system enters protective mode

Potential Causes

The most common technical reasons for Code 1113 on used SH360HD-6 excavators include:

• Open circuit in the ECT sensor wiring harness, often caused by wire chafing near the engine block or firewall penetration points
• Failed ECT sensor with internal open circuit (common after 5,000+ operating hours)
• Corroded or damaged connector terminals at the sensor or ECM interface, particularly on machines operated in marine or high-moisture environments
• Shorted sensor ground wire creating incorrect voltage reference
• ECM internal fault (rare, but possible on high-hour machines with previous electrical issues)

How to Troubleshoot and Fix Code 1113

Step 1: Visual Inspection Begin by locating the ECT sensor on the engine block (typically near the thermostat housing). Inspect the sensor connector and wiring harness for obvious damage, corrosion, or oil contamination. On used excavators, pay special attention to harness routing where wires contact hot engine components or sharp edges.

Step 2: Electrical Testing Disconnect the ECT sensor connector. Using a digital multimeter (DMM), measure resistance across the sensor terminals. A functioning sensor should read approximately 2,000-3,000 ohms at room temperature. If you measure infinite resistance (open circuit), replace the sensor. Next, check for 5-volt reference voltage at the harness connector with ignition on, engine off.

Step 3: Harness Continuity Check Test continuity between the ECM connector pins and the sensor harness connector. Consult the SH360HD-6 service manual for specific pin locations. Check for shorts to voltage or ground. On older machines, corrosion inside connector boots is common—clean with electrical contact cleaner and apply dielectric grease.

Step 4: Clear Code and Monitor After repairs, clear the fault code using Sumitomo diagnostic software or a compatible scan tool. Operate the machine through a complete heat cycle and verify the code does not return.

Disclaimer: This guide provides general troubleshooting information. Always consult the official Sumitomo service manual and consider professional diagnostic assistance for complex electrical issues or if you lack proper testing equipment.