Sumitomo SH260LC-6 Fault Code 117: Complete Diagnostic Guide

What is Sumitomo SH260LC-6 Fault Code 117?

Fault Code 117 on the Sumitomo SH260LC-6 indicates a malfunction in the engine coolant temperature sensor circuit or an abnormal coolant temperature reading detected by the ECM (Engine Control Module). This code specifically relates to the temperature monitoring system that protects the engine from overheating damage.

The coolant temperature sensor is a critical component that sends real-time temperature data to the ECM, which then regulates fuel injection, engine timing, and activates warning systems. On used Sumitomo excavators, this code can trigger engine derating or shutdown protocols to prevent catastrophic engine damage, making immediate diagnosis essential for operational continuity.

Common Symptoms

When Code 117 is active on your SH260LC-6, you may experience:

• Engine warning light illuminated on the instrument panel, often accompanied by a temperature gauge reading abnormally high or low
• Reduced engine power (derate mode) as the ECM enters a protective state
• Hard starting or rough idle, especially when the engine is cold
• Cooling fan running continuously at maximum speed regardless of actual engine temperature
• Black smoke from the exhaust due to improper fuel mixture caused by incorrect temperature readings

Potential Causes

The most common technical reasons for Code 117 on used SH260LC-6 excavators include:

• Faulty coolant temperature sensor – internal resistance breakdown common in machines with 5,000+ operating hours
• Damaged wiring harness – particularly at rub points near the engine block where vibration causes insulation wear
• Corroded or loose electrical connectors – moisture intrusion in the sensor connector is prevalent in excavators operating in wet conditions
• Low coolant level causing air pockets around the sensor, resulting in false readings
• ECM malfunction – rare but possible in older units with voltage spike history
• Thermostat failure causing actual overheating that triggers the sensor warning

How to Troubleshoot and Fix Code 117

Step 1: Visual Inspection Begin by checking the coolant level in the radiator and overflow tank. Inspect the coolant temperature sensor (typically located on the engine block near the thermostat housing) for physical damage, corrosion, or coolant leaks. Examine the wiring harness from the sensor to the ECM for abrasion, cuts, or signs of heat damage—pay special attention to areas where the harness contacts metal surfaces.

Step 2: Electrical Testing Using a digital multimeter, disconnect the coolant temperature sensor connector and measure the sensor's resistance. At room temperature (68°F/20°C), resistance should typically read between 2,000-3,000 ohms (consult your service manual for exact specifications). Test the harness continuity from the sensor connector back to the ECM, checking for open circuits or shorts to ground. Measure voltage supply at the sensor connector with the key on—you should see approximately 5 volts reference voltage from the ECM.

Step 3: Component Replacement and Verification If resistance values are out of specification or the sensor shows visible corrosion, replace the coolant temperature sensor with a genuine Sumitomo or OEM-equivalent part. For used excavators, always apply dielectric grease to connector pins before reassembly to prevent future corrosion. Clear the fault code using diagnostic software (Sumitomo diagnostic tool or compatible scanner) and monitor engine temperature during a full operating cycle to confirm the repair.

Critical for Used Equipment: Before replacing the sensor, inspect all connector terminals for green corrosion and check harness routing for modifications made by previous owners that may cause intermittent faults.

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Disclaimer: This guide provides general diagnostic information. Always consult the official Sumitomo service manual for your specific machine serial number and consider professional diagnosis for complex electrical issues or if you lack proper diagnostic equipment.