Sumitomo SH210LC-5LR Fault Code 118: Complete Diagnostic Guide

What is Sumitomo SH210LC-5LR Fault Code 118?

Fault Code 118 on the Sumitomo SH210LC-5LR indicates a hydraulic pump solenoid valve circuit malfunction, specifically detecting an abnormal current or open/short circuit in the main pump control solenoid.

This code is generated when the Electronic Control Module (ECM) detects voltage irregularities in the pump's proportional solenoid valve circuit. The main pump solenoid regulates hydraulic flow and pressure by adjusting swash plate angle, making it critical for the excavator's overall performance. When this circuit fails, the machine cannot properly modulate hydraulic output, directly impacting digging force, swing speed, and fuel efficiency. For used machines like the SH210LC-5LR, this fault often stems from age-related component degradation rather than catastrophic failure.

Common Symptoms

When Code 118 activates on your Sumitomo excavator, operators typically experience:

• Reduced hydraulic power across all functions, with noticeably slower boom and arm movements
• Erratic pump response where hydraulic pressure fluctuates unexpectedly during operation
• Warning light illumination on the instrument panel, often accompanied by audible alarm
• Engine over-revving without corresponding hydraulic output due to pump angle control loss
• Intermittent performance issues that worsen as the machine warms up, indicating heat-sensitive electrical faults

Potential Causes

The most common technical causes for Code 118 in used SH210LC-5LR excavators include:

• Solenoid coil failure within the main pump assembly due to overheating or age-related insulation breakdown
• Wiring harness damage at known rub points near the pump mounting area where vibration causes wire chafing
• Corroded or loose connector pins at the pump solenoid plug, especially on machines operating in wet/corrosive environments
• ECM internal driver circuit failure affecting the solenoid output stage
• Voltage supply issues from damaged main harness or poor ground connections at the pump frame mount
• Contaminated hydraulic oil causing solenoid valve sticking, which increases current draw beyond specifications

How to Troubleshoot and Fix Code 118

Step 1: Visual Inspection Begin by inspecting the pump solenoid connector for corrosion, bent pins, or moisture intrusion. On used excavators, check the entire wiring harness from the ECM to the pump for abrasion points, particularly where it routes near the swing motor and travel motor assemblies. Look for discolored insulation indicating previous heat damage.

Step 2: Electrical Testing Using a digital multimeter, measure solenoid resistance at the connector (should typically read 8-12 ohms for this model). Then check for voltage supply with ignition on—you should see battery voltage at the power supply pin. Test for continuity in the ground circuit back to the ECM chassis ground point.

Step 3: Dynamic Circuit Testing With the harness reconnected and engine running, use Sumitomo diagnostic software or a compatible scan tool to monitor solenoid current draw in real-time. Abnormal current spikes indicate internal solenoid shorting, while zero current suggests open circuits or ECM driver failure.

Step 4: Component Replacement If testing confirms solenoid failure, replacement requires draining the hydraulic tank and removing the pump cover. For used machines, always replace the connector pigtail simultaneously, as aged connectors often cause repeat failures. Clean all mounting surfaces and apply dielectric grease to new connections.

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