What is Sumitomo SH220LC-6 Fault Code 1?

Fault Code 1 on the Sumitomo SH220LC-6 excavator indicates an Engine Speed Sensor (ESS) malfunction or signal error. This diagnostic trouble code (DTC) is triggered when the Electronic Control Module (ECM) detects an abnormal signal from the engine speed sensor, which monitors crankshaft rotation speed and timing. The engine speed sensor is critical for proper fuel injection timing, idle control, and overall engine performance management on this model's diesel power plant.

This code is particularly important for the SH220LC-6 because the ECM relies on accurate engine speed data to coordinate fuel delivery with hydraulic demands. When this sensor fails or provides erratic signals, the machine's performance and efficiency are directly compromised, potentially leading to unsafe operating conditions.

Common Symptoms

When Fault Code 1 is active on your Sumitomo SH220LC-6, you may experience:

• Check Engine Light illuminated on the instrument panel or warning lamp activation
• Difficult starting or extended cranking time, especially when the engine is cold
• Erratic idle speed with the engine hunting or surging at low RPM
• Loss of power or hesitation during hydraulic operations under load
• Engine stalling unexpectedly during operation or when returning to idle

Potential Causes

The most common technical reasons for Code 1 appearing on used SH220LC-6 excavators include:

• Damaged or contaminated engine speed sensor, often from oil leaks or debris accumulation near the flywheel housing
• Broken or corroded wiring harness connections at the sensor plug, particularly where the harness routes near the engine block (a known wear point on this model)
• Air gap issues between the sensor tip and the flywheel ring gear due to sensor mounting looseness or flywheel wear
• Failed sensor internal electronics from age, heat cycling, or moisture intrusion common in older machines
• ECM connection problems including corroded pins or loose connectors at the control module

How to Troubleshoot and Fix Code 1

Step 1: Visual Inspection Begin by locating the engine speed sensor on the flywheel housing (typically on the driver's side of the engine bell housing). Inspect the sensor and its wiring harness for obvious damage, oil contamination, or loose connections. On used excavators, check for harness chafing where it passes through metal brackets or rubs against the engine block—a common failure point on the SH220LC-6.

Step 2: Check Sensor Air Gap Verify the air gap between the sensor tip and flywheel teeth is within specification (typically 0.5-1.5mm). Use a feeler gauge to measure. If the gap is too large, check the sensor mounting bolt torque and inspect the flywheel teeth for excessive wear or damage.

Step 3: Electrical Testing Using a digital multimeter, measure the sensor's resistance across its two terminals (disconnect the harness first). Compare readings against the manufacturer's specifications (typically 150-300 ohms at room temperature). Also test the wiring harness for continuity from the sensor connector to the ECM, checking for shorts to ground or open circuits.

Step 4: Signal Testing With the sensor reconnected and using a multimeter set to AC voltage, crank the engine and verify the sensor produces an alternating voltage signal (typically 0.5-5V AC). No signal indicates a failed sensor; erratic signals may point to air gap or flywheel issues.

Step 5: Connector and Corrosion Check For used machinery, thoroughly inspect all connector pins for corrosion, bent terminals, or moisture. Clean connections with electrical contact cleaner and apply dielectric grease. Check the ECM ground connections as poor grounding is a frequent culprit in older equipment.

Step 6: Component Replacement If testing confirms sensor failure, replace with an OEM or quality aftermarket engine speed sensor. After replacement, clear the fault code using diagnostic software (Sumitomo diagnostic tool or compatible interface) and perform a test run under load to verify proper operation.

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Disclaimer: This guide provides general diagnostic information for Sumitomo SH220LC-6 excavators. Always consult the manufacturer's service manual for model-specific procedures and specifications. If you're uncomfortable performing electrical diagnostics or lack proper tools, seek assistance from a qualified heavy equipment technician to avoid injury or further damage to the machine.