Sumitomo SH480HD-6 Fault Code 335: Technical Guide

What is Sumitomo SH480HD-6 Fault Code 335?

Fault Code 335 on the Sumitomo SH480HD-6 excavator indicates a malfunction in the Boom Kickout Solenoid Circuit, specifically detecting an abnormal voltage condition or open/short circuit in the electrical pathway controlling the boom automatic stop function. This code is generated when the Electronic Control Module (ECM) detects voltage readings outside the acceptable range (typically 0.5-4.5V) for the boom kickout solenoid valve circuit.

The boom kickout system is critical for operational safety and productivity on the SH480HD-6, as it prevents the boom from traveling beyond preset limits during excavation cycles. When this circuit fails, operators lose automatic boom limiting functionality, which can reduce digging efficiency and potentially lead to unsafe boom positioning, especially in confined work areas or near overhead obstacles.

Common Symptoms

• Boom kickout function becomes inoperative – the boom continues traveling beyond the preset stop position during digging operations
• Warning light illumination on the instrument cluster, often accompanied by a continuous or intermittent audible alarm
• Error message displayed on the multi-function monitor showing "Code 335" or "Boom Kickout System Fault"
• Reduced digging cycle efficiency as operators must manually control boom limits without automated assistance
• Intermittent functionality where the kickout works sporadically, indicating loose connections or failing components

Potential Causes

Electrical Connection Issues: Corroded or loose connector pins at the boom kickout solenoid valve (common on used machines with 5,000+ hours due to exposure to moisture and vibration)

Damaged Wiring Harness: Wire chafing or breaks in the harness routing near the boom cylinder area, particularly where the harness passes through the boom pivot point—a known wear point on SH480HD-6 models

Failed Boom Kickout Solenoid Valve: Internal coil failure or mechanical seizure of the solenoid itself, typically occurring after 8,000-10,000 operating hours

ECM Internal Fault: Less common, but possible driver circuit failure within the controller itself, especially in machines exposed to electrical surges or water intrusion

Faulty Boom Angle Sensor: Malfunctioning position sensor providing incorrect feedback, causing the ECM to register circuit errors

How to Troubleshoot and Fix Code 335

Step 1: Visual Inspection and Connector Check Begin by locating the boom kickout solenoid valve mounted on the main control valve assembly. Inspect the electrical connector for corrosion, bent pins, or moisture intrusion. On used excavators, carefully examine the wiring harness routing from the valve back to the ECM, paying special attention to areas where the harness contacts the boom structure or passes through cable guides. Look for wire insulation damage, especially at the boom pivot point where repeated flexing occurs.

Step 2: Electrical Testing with Multimeter Disconnect the solenoid connector and use a digital multimeter (DMM) to measure solenoid coil resistance. The boom kickout solenoid should typically read between 18-25 ohms (consult your service manual for exact specifications). Next, check for supply voltage at the harness connector with the ignition on—you should see approximately 12V DC. Test for continuity from the connector back to the ECM to identify any open circuits in the wiring.

Step 3: Advanced Diagnostics and Component Replacement Connect Sumitomo diagnostic software (or compatible equipment like Hitachi Dr.EX if available for this platform) to read live data and perform solenoid activation tests. Command the solenoid on/off while monitoring voltage and current draw. If the solenoid tests faulty (high resistance, no click sound, or draws excessive current), replace the boom kickout solenoid valve. For used machines, always apply dielectric grease to connectors during reassembly to prevent future corrosion. If all components test good, suspect ECM driver circuit failure and consult with a certified Sumitomo technician for controller diagnostics.

---

Disclaimer: This guide provides general technical information for diagnostic purposes. Always consult the official Sumitomo service manual for your specific serial number and seek qualified professional assistance for complex electrical repairs. Improper diagnosis can lead to component damage or safety hazards.