Sumitomo SH360HD-6 Fault Code 117: Complete Diagnostic Guide

What is Sumitomo SH360HD-6 Fault Code 117?

Fault Code 117 on the Sumitomo SH360HD-6 excavator 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 circuit, typically exceeding 4.8-4.9 volts.

The ECT sensor is a critical component in the engine management system that monitors coolant temperature and sends voltage signals to the ECM. This data controls fuel injection timing, idle speed, and cooling fan operation. On used Sumitomo excavators, this code can lead to improper engine temperature management, potentially causing overheating or poor combustion efficiency that reduces machine performance and fuel economy.

Common Symptoms

When Code 117 is active on your SH360HD-6, you may experience:

• Check Engine Light or malfunction indicator lamp illuminated on the instrument panel
• Cooling fan running continuously at high speed, even when the engine is cold
• Hard starting or rough idle, particularly during cold starts, as the ECM defaults to failsafe temperature values
• Reduced engine power or derate mode activation to protect the engine from perceived overheating
• Inaccurate temperature gauge readings, often showing unrealistically low temperatures or erratic needle movement

Potential Causes

The most common technical reasons for Code 117 on used SH360HD-6 excavators include:

• Open circuit in the ECT sensor wiring harness, often caused by wire chafing against the engine block near the sensor mounting location
• Failed ECT sensor with internal open circuit, common in machines with 6,000+ operating hours
• Corroded or loose connector pins at the sensor or ECM connection points due to moisture intrusion
• Damaged sensor ground circuit or poor ground connection at the engine block
• ECM internal fault (rare, but possible in older machines with electrical system stress)

How to Troubleshoot and Fix Code 117

Step 1: Visual Inspection Begin by inspecting the ECT sensor located on the engine block (typically near the thermostat housing). Check the wiring harness for visible damage, abrasion points where wires contact metal surfaces, or melted insulation. On used excavators, pay special attention to connector corrosion—disconnect the sensor and inspect pins for green oxidation or moisture.

Step 2: Sensor Resistance Testing Using a digital multimeter (DMM), measure the resistance across the ECT sensor terminals with the sensor disconnected. At room temperature (68°F/20°C), resistance should typically read 2,000-3,000 ohms (consult service manual for exact specifications). If resistance reads infinite (open circuit), the sensor has failed and requires replacement.

Step 3: Circuit Voltage Testing With the ignition on and sensor disconnected, measure voltage at the harness connector going to the ECM. You should see approximately 5 volts reference voltage on the signal wire. If voltage reads close to battery voltage or above 5V, there's likely a short to power in the wiring harness between the sensor and ECM.

Step 4: Ground Circuit Verification Test continuity between the sensor ground wire and a known good engine ground using your multimeter. Resistance should be less than 1 ohm. For used machines, clean the ground connection point on the engine block, as corrosion commonly causes high resistance.

Step 5: Repair or Replace Replace damaged wiring harnesses, ensuring proper routing away from heat sources and moving components. Secure with new protective loom and zip ties. If the sensor tests faulty, install a genuine or OEM-equivalent ECT sensor with a new sealing washer. Clear codes using diagnostic software compatible with Sumitomo systems and verify repair with a test run.

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Disclaimer: This guide provides general troubleshooting information for Code 117. Always consult the official Sumitomo service manual for your specific machine serial number. If you're uncomfortable performing electrical diagnostics on used excavators, contact a certified heavy equipment technician to prevent further damage to electrical systems.