What is Hitachi ZX360LC-5G Fault Code 13303-2?

Fault Code 13303-2 indicates a malfunction in the main pump solenoid valve circuit, specifically a short circuit to ground or abnormal voltage detected in the hydraulic pump control system. This diagnostic trouble code (DTC) is generated when the Electronic Control Module (ECM) detects electrical irregularities in the proportional solenoid valve that regulates the main hydraulic pump's displacement and output pressure.

In the ZX360LC-5G, this code directly affects the machine's ability to modulate hydraulic flow based on operational demand. The main pump solenoid controls the swash plate angle, which determines hydraulic output. When this circuit fails, the excavator cannot properly match hydraulic power to the work being performed, leading to reduced efficiency and potential damage to hydraulic components.

Common Symptoms

• Sudden loss of hydraulic power across all functions (boom, arm, bucket, swing)
• ECM warning light illuminated on the instrument cluster with possible audible alarm
• Engine may operate normally, but hydraulic functions respond sluggishly or intermittently
• Pump remains in fixed displacement mode, unable to adjust to load demands
• Increased fuel consumption due to inefficient hydraulic operation

Potential Causes

The most common causes of Code 13303-2 on used ZX360LC-5G excavators include:

• Damaged wiring harness near the main pump area, where vibration and heat cause insulation breakdown
• Corroded or moisture-damaged connectors at the solenoid valve plug (common on machines operating in wet conditions)
• Failed main pump proportional solenoid valve due to internal coil short or contamination
• Chafed wires at known rub points near the hydraulic pump mounting bracket
• ECM internal fault (less common, but possible on high-hour machines)
• Voltage supply issues from the main power relay or blown fuses

How to Troubleshoot and Fix Code 13303-2

Step 1: Visual Inspection Begin by inspecting the wiring harness from the ECM to the main pump solenoid valve. On used excavators, check for abrasion points where the harness contacts the pump housing or frame. Look for damaged insulation, particularly near heat sources like the hydraulic lines.

Step 2: Connector and Ground Testing Disconnect the solenoid valve connector and inspect for corrosion, bent pins, or moisture. Using a digital multimeter, check for continuity between the solenoid terminals and ground—there should be no continuity (infinite resistance). Measure resistance across the solenoid coil terminals; typical values range from 10-30 ohms (consult service manual for exact specifications).

Step 3: Voltage Supply Check With the ignition on and connector attached, backprobe the solenoid connector to verify 12-24V supply voltage (depending on system specification). If voltage is absent, trace back to the ECM output and check fuses and relays.

Step 4: Solenoid Replacement or Harness Repair If testing confirms a short to ground in the wiring, repair or replace the affected harness section. If the solenoid coil is shorted, replace the proportional solenoid valve assembly. For used machines, always apply dielectric grease to connectors during reassembly to prevent future corrosion.

Step 5: Clear Code and Test Use Hitachi Dr.EX diagnostic software or equivalent to clear the fault code. Operate the machine under load and monitor for code recurrence.

---

Disclaimer: This guide provides general troubleshooting information. Always consult the official Hitachi service manual for your specific machine serial number and seek professional assistance for complex electrical diagnostics or hydraulic system repairs.