Sumitomo SH210LC-5LR Fault Code 117: Technical Guide

What is Sumitomo SH210LC-5LR Fault Code 117?

Fault Code 117 on the Sumitomo SH210LC-5LR indicates a malfunction in the Engine Coolant Temperature (ECT) Sensor circuit, specifically detecting an abnormal voltage signal or open/short circuit condition. This code is triggered when the Electronic Control Module (ECM) receives sensor readings outside the expected voltage range (typically 0.5-4.5V), suggesting the engine temperature monitoring system cannot accurately track thermal conditions.

This fault is critical for the Isuzu 6BG1 engine used in the SH210LC-5LR because proper coolant temperature monitoring directly affects fuel injection timing, engine protection protocols, and overall performance. When this sensor circuit fails, the ECM may default to fail-safe mode, limiting machine productivity and potentially causing long-term engine damage if overheating goes undetected.

Common Symptoms

• Check Engine Light or Warning Lamp illuminated on the instrument cluster
• Engine running in derate mode with reduced power output or RPM limitation
• Erratic temperature gauge readings – displaying full hot, full cold, or fluctuating wildly
• Hard starting conditions, especially when the engine is cold, due to incorrect fuel mixture compensation
• Excessive black smoke from the exhaust as the ECM defaults to a rich fuel map without proper temperature data

Potential Causes

Sensor-Related Failures:

• Failed ECT sensor due to internal resistance breakdown (common after 5,000+ operating hours)
• Corrosion on sensor terminals from coolant seepage at the sensor mounting point

Wiring and Connection Issues:

• Chafed or broken wiring in the harness between the ECT sensor and ECM – particularly where the harness passes near the engine block or sharp metal edges
• Corroded connector pins at the sensor plug or ECM connector (especially common in used excavators exposed to moisture)
• Loose ground connections affecting the sensor reference voltage

ECM-Related Problems:

• Internal ECM circuit failure on the sensor input channel (rare but possible in high-hour machines)

How to Troubleshoot and Fix Code 117

Step 1: Visual Inspection Inspect the ECT sensor (typically located on the engine's thermostat housing or cylinder head) for coolant leaks, damaged wiring, or corroded connectors. On used excavators, check for harness wear points where cables contact the engine block during vibration.

Step 2: Sensor Resistance Testing Disconnect the sensor and use a digital multimeter to measure resistance across the sensor terminals. At 68°F (20°C), resistance should be approximately 2,000-3,000 ohms (consult service manual for exact specifications). If readings are infinite (open circuit) or near zero (short circuit), replace the sensor.

Step 3: Circuit Voltage Check With the sensor disconnected and ignition ON, measure voltage at the harness connector. You should see approximately 5V reference voltage from the ECM. If voltage is absent, trace wiring back to the ECM for breaks or check the ECM ground circuit.

Step 4: Connector and Harness Inspection Clean all connector pins with electrical contact cleaner and inspect for corrosion (green/white deposits). On used machines, verify the sensor ground wire has less than 0.5 ohms resistance to chassis ground.

Step 5: Clear Code and Test After repairs, clear the fault code using diagnostic software (Sumitomo proprietary tools or compatible OBD systems) and operate the machine through a thermal cycle to confirm repair.

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Disclaimer: This guide provides general troubleshooting information. Always consult the official Sumitomo service manual for your specific machine serial number and consider professional diagnostic assistance for complex electrical issues or if you're unfamiliar with high-voltage systems.