Sumitomo SH350HD-5 Fault Code 1113: Complete Diagnostic Guide

What is Sumitomo SH350HD-5 Fault Code 1113?

Fault Code 1113 on the Sumitomo SH350HD-5 indicates a Main Relief Valve Solenoid Circuit malfunction, specifically detecting an open circuit or abnormal voltage in the proportional pressure control system. This code is triggered when the Electronic Control Module (ECM) detects that the electrical signal to the main relief valve solenoid is outside the normal operating range of 0.5-4.5 volts.

The main relief valve solenoid controls hydraulic system pressure, which is critical for the SH350HD-5's performance. When this circuit malfunctions, the excavator cannot properly regulate hydraulic pressure across the boom, arm, and swing functions. This system is particularly important in Sumitomo's load-sensing hydraulic architecture, where precise pressure control directly impacts fuel efficiency and operational smoothness.

Common Symptoms

When Code 1113 is active, operators typically experience:

• Reduced hydraulic power across all functions, with noticeably sluggish boom and arm movements
• Amber warning light on the instrument cluster, often accompanied by a continuous audible alarm
• Automatic engine derate to protect hydraulic components, limiting RPM to approximately 1,400-1,600
• Erratic digging force or inconsistent breakout force during bucket operations
• Hydraulic overheat warnings in some cases, as the system cannot properly modulate pressure

Potential Causes

The most common technical failures triggering Code 1113 on used SH350HD-5 excavators include:

• Broken or corroded wiring in the harness between the ECM and relief valve solenoid (common failure point near the swing bearing)
• Failed proportional solenoid coil within the main relief valve assembly, typically showing resistance outside the 8-12 ohm specification
• Connector pin corrosion at the 6-pin Deutsch connector located on the main control valve block
• Damaged ECM output driver circuit due to previous electrical surges or water intrusion
• Chafed harness where the wire bundle passes through the upper structure near the hydraulic tank

How to Troubleshoot and Fix Code 1113

Step 1: Initial Inspection Using a multimeter, check for battery voltage (24V DC) at the relief valve solenoid connector with the ignition on. If no voltage is present, trace the power supply wire back to the ECM, inspecting for breaks or damage at known wear points.

Step 2: Solenoid Resistance Test Disconnect the solenoid connector and measure resistance across the solenoid terminals. The specification is 8-12 ohms. Readings outside this range indicate solenoid failure. On used excavators, also inspect the connector pins for green corrosion or bent terminals—common on machines operating in coastal or high-humidity environments.

Step 3: Harness Continuity Check Perform a continuity test from the ECM connector (Pin 47 for signal, Pin 48 for ground) to the valve solenoid. Any reading above 2 ohms indicates damaged wiring. Pay special attention to the harness routing through the swing post area, where repeated rotation causes insulation wear.

Step 4: Voltage Signal Verification Using Sumitomo diagnostic software (or compatible J1939 reader), command the solenoid to various percentages while monitoring actual voltage output. The signal should proportionally increase from 0.5V to 4.5V. Inconsistent readings point to ECM driver failure.

For used excavators, always clean all connectors with electrical contact cleaner and apply dielectric grease before reassembly. Replace damaged harness sections with OEM-spec wire rated for hydraulic oil exposure.

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Disclaimer: This guide provides general diagnostic procedures. Always consult the official Sumitomo service manual and consider professional diagnosis for complex electrical issues. Improper repairs may cause further damage to hydraulic or electrical systems.