What is Hitachi EX200-3 Fault Code 1100-2?

Fault Code 1100-2 on the Hitachi EX200-3 excavator indicates a malfunction in the engine speed sensor circuit, specifically a low voltage or open circuit condition. This code is triggered when the Electronic Control Module (ECM) detects insufficient signal voltage from the engine speed sensor (also called the crankshaft position sensor), which monitors engine RPM and crankshaft positioning.

This sensor is critical for the EX200-3's Isuzu 6BG1 engine management system because it provides real-time data that controls fuel injection timing, engine governing, and overall performance. Without accurate speed sensor readings, the ECM cannot properly regulate engine operation, leading to performance degradation or complete shutdown to prevent engine damage.

Common Symptoms

When Code 1100-2 is active on your Hitachi EX200-3, operators typically experience:

• Engine cranks but fails to start or starts with extreme difficulty and rough idling
• Sudden engine stalling during operation, particularly under load
• Loss of engine power or inability to reach rated RPM
• Warning lamp illumination on the instrument panel (check engine light)
• Erratic engine behavior including inconsistent throttle response and hunting RPM

Potential Causes

The most common technical causes for Code 1100-2 on used EX200-3 excavators include:

• Damaged or corroded engine speed sensor due to heat exposure and age-related deterioration
• Broken or frayed wiring harness near the sensor mounting location on the flywheel housing, a known rub point on this model
• Corroded or loose connector pins at the sensor plug, especially in machines with water intrusion history
• Failed engine speed sensor with internal coil breakdown (common after 8,000+ operating hours)
• ECM internal fault or poor ground connection at the ECM mounting bracket
• Excessive air gap between the sensor tip and flywheel ring gear teeth due to sensor mounting looseness

How to Troubleshoot and Fix Code 1100-2

Step 1: Visual Inspection Locate the engine speed sensor on the flywheel housing (driver's side of the engine block). Inspect the wiring harness for visible damage, especially where it routes near hot exhaust components or sharp metal edges. Check the connector for corrosion, bent pins, or moisture intrusion—common issues on used excavators stored outdoors.

Step 2: Sensor Testing Disconnect the sensor connector and use a digital multimeter to measure resistance across the sensor terminals. The typical specification for the Isuzu 6BG1 engine speed sensor is 150-300 ohms at room temperature. Readings outside this range indicate sensor failure requiring replacement.

Step 3: Circuit Voltage Check With the ignition on (engine off), backprobe the ECM side of the harness connector and measure voltage. You should see approximately 5 volts reference voltage from the ECM. No voltage indicates wiring issues or ECM problems. Also check for proper ground continuity (less than 1 ohm resistance to chassis ground).

Step 4: Air Gap Verification If the sensor tests good electrically, verify the air gap between the sensor tip and flywheel teeth. The specification is typically 0.5-1.5mm. Use a feeler gauge to check—excessive gap prevents proper magnetic signal generation.

Step 5: Harness and Connector Repair For used excavators, carefully inspect the entire sensor harness for hidden damage under protective loom. Replace any damaged sections with proper gauge wire and use dielectric grease on connector pins to prevent future corrosion.

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Disclaimer: This guide provides general troubleshooting information for Code 1100-2. Always consult the Hitachi service manual for your specific serial number range and consider professional diagnostic assistance for complex electrical issues or ECM replacement procedures.