Doosan DX230LC-9C Fault Code E520708-12: Complete Diagnostic Guide

What is Doosan DX230LC-9C Fault Code E520708-12?

Fault Code E520708-12 indicates a hydraulic pump solenoid valve circuit malfunction with an open circuit or short to ground condition in the main control valve system. This code is triggered when the Electronic Control Module (ECM) detects abnormal electrical resistance or voltage in the proportional solenoid valve circuit that controls hydraulic pump displacement.

This fault directly impacts the DX230LC-9C's load-sensing hydraulic system, which regulates pump flow based on operational demand. When this circuit fails, the excavator cannot properly adjust hydraulic pressure and flow, severely affecting digging force, swing speed, and overall machine performance. For used excavators, this code often appears due to electrical degradation rather than mechanical pump failure.

Common Symptoms

• Reduced hydraulic power across all functions (digging, lifting, swinging)
• Engine RPM fluctuations or failure to maintain target speed under load
• Amber hydraulic warning light illuminated on the instrument cluster
• Erratic boom/arm response or inconsistent bucket breakout force
• Error message displayed on the LCD monitor indicating hydraulic system fault
• Engine derate mode activation limiting maximum engine RPM to protect the system

Potential Causes

The E520708-12 code typically results from specific electrical failures common in used machines:

• Damaged wiring harness between the ECM and main control valve (particularly at routing points near the swing bearing where cables experience repetitive flexing)
• Corroded connector pins at the solenoid valve connector (C-407) due to water infiltration from worn cab floor seals
• Failed proportional solenoid valve internal coil winding breakdown
• Chafed wiring rubbing against the hydraulic tank mounting bracket (known issue on DX230LC-9C models)
• ECM internal driver circuit failure (less common but possible in high-hour machines)
• Poor ground connection at G-203 ground point on main frame

How to Troubleshoot and Fix Code E520708-12

Step 1: Visual Harness Inspection Inspect the main harness routing from the ECM (located behind the operator seat) to the main control valve on the right side of the pump. Check for abraded insulation, particularly where the harness passes through the swing post and near hydraulic line clamps. On used excavators, this wear point causes 60% of E520708-12 codes.

Step 2: Connector and Pin Testing Disconnect connector C-407 at the main control valve. Inspect for corrosion, bent pins, or moisture. Using a digital multimeter, measure resistance between ECM pins (consult wiring diagram) and solenoid terminals. Specification should be 8-12 ohms at 20°C. Check for short to ground by measuring resistance between solenoid pins and valve body (should read >10 MΩ).

Step 3: Voltage Supply Verification With ignition on and engine off, use Doosan DMS (Diagnostic Master Software) or compatible scan tool to command solenoid actuation. Measure voltage at connector C-407 during activation—should read 12V PWM signal. No voltage indicates ECM driver failure; intermittent voltage suggests harness issues.

Step 4: Solenoid Replacement or Repair If resistance and voltage tests pass but code persists, replace the proportional solenoid valve assembly (part number varies by serial number). For used machines, always replace connector pigtails and apply dielectric grease to prevent future corrosion.

Disclaimer: This guide provides general diagnostic procedures. Always consult the official Doosan service manual for your specific serial number. If unfamiliar with high-pressure hydraulic systems or electrical diagnostics, seek assistance from a certified Doosan technician to prevent injury or further machine damage.