What is Hyundai R335LC-9T Fault Code 110-2?

Fault Code 110-2 on the Hyundai R335LC-9T excavator indicates an Engine Speed Sensor Circuit Low Voltage condition. This diagnostic trouble code (DTC) triggers when the Engine Control Module (ECM) detects abnormally low voltage signals from the engine speed sensor (also known as the crankshaft position sensor), typically below the manufacturer's specified threshold of approximately 0.5 volts during cranking.

This code is critical for the R335LC-9T's performance because the engine speed sensor provides real-time data to the ECM about crankshaft rotation and timing. Without accurate speed readings, the ECM cannot properly control fuel injection timing, engine RPM limits, or coordinate with the hydraulic system's load-sensing functions. On used machines, this fault can lead to hard starting, power loss, or complete shutdown as a protective measure.

Common Symptoms

When fault code 110-2 is active on your Hyundai R335LC-9T, you may experience:

• Engine cranks but fails to start or requires extended cranking time before firing
• Check Engine Light (CEL) illuminated on the instrument cluster with possible fault code display
• Erratic engine RPM readings on the gauge or sudden engine stalling during operation
• Loss of engine power or failure to reach full operating RPM under load
• Intermittent starting issues that worsen in cold weather conditions

Potential Causes

The most common technical causes for code 110-2 on used R335LC-9T excavators include:

• Damaged or corroded engine speed sensor connector – particularly common on machines with 5,000+ operating hours due to exposure to engine heat and vibration
• Worn or broken sensor wiring harness at the harness routing point near the flywheel housing, a known rub point on this model
• Failed engine speed sensor itself due to internal coil breakdown or bearing surface wear
• Low supply voltage from ECM caused by corroded ECM pins or ground connection issues
• Contaminated sensor air gap from metal debris, oil sludge, or flywheel ring gear damage
• ECM internal fault affecting the sensor signal processing circuit (less common)

How to Troubleshoot and Fix Code 110-2

Step 1: Visual Inspection and Connector Check Begin by locating the engine speed sensor on the bell housing near the flywheel (driver's side of the engine block). Disconnect the sensor connector and inspect for corrosion, bent pins, moisture, or oil contamination. Clean connections with electrical contact cleaner and check the rubber seal integrity. On used excavators, this step alone resolves approximately 30% of low voltage faults.

Step 2: Sensor Resistance and Wiring Testing Using a digital multimeter (DMM), measure the sensor's internal resistance across its terminals. Hyundai specifies approximately 850-1,200 ohms at 68°F for the R335LC-9T's inductive-type sensor. Next, perform a voltage drop test on the wiring harness by back-probing the connector while cranking the engine – you should see AC voltage pulses between 0.5-5.0 volts. Check continuity from the sensor connector back to the ECM pins and ensure less than 1 ohm resistance.

Step 3: Check Sensor Air Gap and Physical Condition Remove the sensor completely and inspect the sensor tip for metal debris or physical damage. Verify the air gap between the sensor and flywheel ring gear is within specification (0.5-1.5mm typically). Examine the flywheel ring gear teeth for damage or missing teeth that could disrupt the magnetic field.

Step 4: Harness Inspection for Known Wear Points On used R335LC-9T machines, carefully trace the sensor harness from the sensor to the main engine harness connector, paying special attention to the routing clamp near the engine mount where vibration-induced chafing commonly occurs. Look for insulation wear, exposed wires, or signs of previous repairs with electrical tape.

Step 5: Component Replacement and Verification If testing confirms a faulty sensor, replace with a genuine Hyundai or OEM-equivalent engine speed sensor (part number typically 39310-84401 or similar for this model). After replacement, clear the fault code using Hi-SCANPro diagnostic software or equivalent Hyundai-compatible scan tool, and verify proper operation through a complete work cycle.

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Disclaimer: This guide provides general troubleshooting information for experienced technicians. Always consult the official Hyundai service manual for your specific machine serial number, and consider professional diagnostic assistance for complex electrical issues. Improper repairs may cause additional damage or safety hazards.