What is Sany Excavator Fault Code P335?

Fault Code P335 on Sany excavators indicates a malfunction in the Boom Raise Solenoid Valve Circuit, specifically detecting an open circuit or short circuit condition in the electrical pathway controlling the boom raise function. This diagnostic trouble code (DTC) is generated when the Electronic Control Module (ECM) detects abnormal voltage or resistance values outside the manufacturer's specified parameters for the boom raise proportional solenoid valve.

This fault is critical for Sany excavator operation because the boom raise circuit directly controls one of the machine's primary hydraulic functions. When P335 is active, the ECM may limit or completely disable boom operation to prevent potential damage to hydraulic components or electrical systems. For used excavators, this code often signals deterioration in wiring harnesses or solenoid coils that have accumulated operational hours and environmental exposure.

Common Symptoms

When fault code P335 is active, operators typically experience:

• Boom raise function becomes unresponsive or intermittent, with the boom failing to lift or responding erratically to joystick commands
• Warning light or fault indicator illuminated on the instrument cluster, often accompanied by a fault code display
• Hydraulic system operating in derate mode, limiting machine productivity and cycle times
• Audible alarm or buzzer activation when attempting boom raise operations
• Complete loss of boom control in severe cases, while other hydraulic functions may continue operating normally

Potential Causes

The most common technical reasons for P335 activation on Sany excavators include:

• Damaged or corroded wiring harness between the ECM and boom raise solenoid valve, particularly at harness routing points near the boom pivot where flexing occurs
• Failed boom raise proportional solenoid valve coil, common in used machines with high operational hours due to thermal cycling and vibration
• Connector corrosion or pin contact issues at the solenoid valve connector or ECM interface, especially on machines operated in wet or corrosive environments
• Shorted or open circuit conditions caused by harness chafing against frame components or hydraulic lines
• ECM internal fault affecting the solenoid driver circuit (less common but possible in older machines)
• Voltage supply issues from the main power distribution system affecting solenoid operation

How to Troubleshoot and Fix Code P335

Step 1: Initial Visual Inspection Begin by thoroughly inspecting the wiring harness from the ECM to the boom raise solenoid valve. On used excavators, pay special attention to harness routing points where the cables pass through the boom pivot area and along the upper structure. Look for visible signs of wire insulation damage, chafing, burns, or connector corrosion. Check all connector pins for bent contacts, moisture intrusion, or verdigris buildup.

Step 2: Electrical Testing with Multimeter Disconnect the boom raise solenoid valve connector and measure the solenoid coil resistance using a digital multimeter. Typical resistance values should fall between 8-15 ohms (consult your Sany service manual for exact specifications). Next, perform a continuity test on the harness from the ECM connector to the solenoid valve connector with all components disconnected. Check for open circuits (infinite resistance) or short circuits to ground (near-zero resistance when tested against chassis ground).

Step 3: Voltage Supply Verification With the ignition on and engine running, backprobe the solenoid valve connector to verify proper voltage supply from the ECM. The control signal should show variable voltage (typically 0-12V or PWM signal) when the boom raise function is commanded. If voltage is absent or constant, the issue likely resides in the ECM driver circuit or associated power supply circuits.

Step 4: Component Replacement and Verification If testing reveals a failed solenoid coil, replace the boom raise proportional solenoid valve with OEM or high-quality aftermarket parts. For harness damage on used excavators, repair or replace the affected section, ensuring proper routing away from sharp edges and heat sources. After repairs, clear the fault code using Sany diagnostic software or a compatible scan tool, then cycle the boom raise function multiple times to verify proper operation and confirm the code does not return.

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Disclaimer: This guide provides general troubleshooting information for Sany excavator fault code P335. Hydraulic and electrical systems operate under high pressure and voltage. Always consult your Sany service manual for model-specific procedures and specifications. If you lack proper diagnostic tools or experience with heavy equipment electrical systems, consult a certified Sany technician or qualified heavy equipment mechanic to prevent injury or further machine damage.