Sumitomo SH210LC-5LR Fault Code 335: Complete Diagnostic Guide

What is Sumitomo SH210LC-5LR Fault Code 335?

Fault Code 335 on the Sumitomo SH210LC-5LR indicates a malfunction in the engine speed sensor circuit or an abnormal signal from the crankshaft position sensor system. This diagnostic trouble code (DTC) is triggered when the Electronic Control Module (ECM) detects an inconsistent, intermittent, or missing signal from the engine speed sensor during operation.

The engine speed sensor is critical for this excavator's performance because it provides real-time data to the ECM about crankshaft rotation speed and position. Without accurate readings, the ECM cannot properly control fuel injection timing, engine governor functions, or coordinate hydraulic pump output. On used Sumitomo excavators, this code often appears due to sensor degradation, wiring harness damage from vibration, or connector corrosion accumulated over thousands of operating hours.

Common Symptoms

When Code 335 is active on your SH210LC-5LR, operators typically experience:

• Engine stalling or difficulty starting, particularly when cold or after extended idle periods
• Erratic engine RPM fluctuations during operation, causing inconsistent hydraulic performance
• Loss of power or engine derate mode, limiting maximum engine speed to protect components
• Illuminated malfunction warning light on the instrument cluster (typically amber engine symbol)
• Rough idle or misfiring sensations transmitted through the operator cabin

Potential Causes

The most common technical reasons for Code 335 on used SH210LC-5LR excavators include:

• Failed or contaminated engine speed sensor due to oil leakage, metal debris accumulation, or internal component wear
• Damaged wiring harness between the sensor and ECM, particularly at known rub points near the engine mount brackets and fuel injection pump area
• Corroded or loose electrical connectors at the sensor plug or ECM interface, common in machines operating in wet or coastal environments
• Worn crankshaft trigger wheel or damaged reluctor ring teeth causing irregular signal generation
• ECM internal circuit failure or corrupted calibration data (less common but possible in high-hour machines)
• Inadequate sensor air gap due to improper installation or mounting bracket deterioration

How to Troubleshoot and Fix Code 335

Step 1: Visual Inspection Begin by locating the engine speed sensor (typically mounted on the engine block near the flywheel housing). Inspect the sensor body for physical damage, oil contamination, or metal shavings. Check the wiring harness for abraded insulation, especially where it contacts frame members or moves with engine vibration. On used excavators, pay special attention to connector pins for corrosion or bent terminals—clean with electrical contact cleaner if necessary.

Step 2: Electrical Testing Using a digital multimeter, disconnect the sensor and measure its resistance (typically 190-250 ohms for most Sumitomo applications, but verify with service manual specifications). Test harness continuity from the sensor connector to the ECM pins, checking for opens or shorts to ground. Measure the sensor output voltage while cranking the engine—you should see an AC voltage signal that increases with RPM (usually 0.5-5V AC).

Step 3: Sensor Gap and Mechanical Verification Check the air gap between the sensor tip and crankshaft trigger wheel using a feeler gauge (specification typically 0.5-1.5mm). Inspect the trigger wheel teeth for damage or excessive wear patterns. If all electrical tests pass but the code persists, consider ECM reprogramming or replacement, though sensor replacement resolves 80% of Code 335 cases on used machines.

Step 4: Clear Code and Test After repairs, clear the fault code using Sumitomo diagnostic software or a compatible scan tool. Operate the machine through various load conditions and monitor for code recurrence. For persistent issues on high-hour machines, inspect ECM ground connections and verify battery voltage stability during cranking.

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Disclaimer: This guide provides general diagnostic procedures for Sumitomo SH210LC-5LR excavators. Always consult the manufacturer's service manual for exact specifications and procedures. If you're unfamiliar with electrical diagnostics or lack proper tools, consult a certified heavy equipment technician to prevent further damage or safety hazards.