Sany Excavator Fault Code P593: Complete Diagnostic Guide

What is Sany General Fault Code P593?

Fault Code P593 indicates a hydraulic pump solenoid valve circuit malfunction or abnormal signal detected by the Electronic Control Module (ECM). This code specifically relates to the main pump control system, which regulates hydraulic flow and pressure based on operator demand and load conditions.

In Sany excavators, the hydraulic pump solenoid valve controls variable displacement, allowing the machine to adjust hydraulic output for optimal fuel efficiency and performance. When the ECM detects voltage irregularities, open circuits, or short circuits in this solenoid's control path, it triggers P593. This is critical because improper pump control directly affects digging force, swing speed, and overall machine responsiveness—key performance metrics for excavator operation.

Common Symptoms

When P593 is active, operators typically experience:

• Warning light illumination on the instrument cluster with reduced engine power
• Erratic hydraulic response or inconsistent digging force during operation
• Sluggish boom, arm, or bucket movement despite normal engine RPM
• Intermittent loss of hydraulic power, especially under heavy loads
• Engine derating to protect the hydraulic system from damage

Potential Causes

The most common technical causes for P593 in used Sany excavators include:

• Worn or failed hydraulic pump solenoid valve due to heat cycling and contamination
• Damaged wiring harness at known rub points near the hydraulic pump mounting area
• Corroded or loose electrical connectors at the solenoid valve plug
• Low voltage supply from failing alternator or weak battery (less than 12.5V)
• ECM internal fault or corrupted calibration files (less common)
• Hydraulic oil contamination causing solenoid valve sticking or blockage

How to Troubleshoot and Fix Code P593

Step 1: Visual Inspection Inspect the hydraulic pump solenoid valve connector and wiring harness for physical damage, corrosion, or oil contamination. On used excavators, check harness routing where it contacts the engine block or frame—a common wear point causing intermittent shorts.

Step 2: Electrical Testing Using a digital multimeter, measure solenoid resistance (typically 8-15 ohms) and supply voltage (should be 12V+ with key on). Check for continuity between ECM pin and solenoid connector. Verify ground circuit integrity (less than 0.5 ohms resistance).

Step 3: Solenoid Function Test Connect Sany diagnostic software (SY Scanner or equivalent) to perform active solenoid tests. Monitor command vs. actual current draw. Replace the solenoid if it fails to actuate or draws excessive current (above 2.5A).

Step 4: Harness and Connector Service Clean all connector pins with electrical contact cleaner and apply dielectric grease. Repair any chafed wires with proper gauge marine-grade wire and heat shrink. For used machines, this often resolves intermittent codes without parts replacement.

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Disclaimer: This guide provides general diagnostic information. Always consult your Sany service manual and consider professional technician assistance for complex repairs, especially when working with high-pressure hydraulic systems.