What is Hitachi ZX350K-5G Fault Code 14105-2?

Fault Code 14105-2 on the Hitachi ZX350K-5G excavator indicates a hydraulic pump solenoid valve circuit malfunction, specifically detecting an abnormal voltage or open circuit condition in the pump control system. This diagnostic trouble code (DTC) is generated by the machine's Electronic Control Module (ECM) when it detects electrical irregularities in the solenoid valve circuit that regulates hydraulic pump flow and pressure.

The ZX350K-5G utilizes electronically-controlled variable displacement hydraulic pumps that adjust output based on load demand. The pump solenoid valve receives pulse-width modulated (PWM) signals from the ECM to control pump swash plate angle, directly affecting hydraulic flow. When Code 14105-2 triggers, this critical communication pathway is compromised, potentially reducing machine efficiency and hydraulic performance. For used excavators operating in demanding conditions, this code often signals deteriorating electrical connections or component wear that requires immediate attention to prevent costly hydraulic system damage.

Common Symptoms

• Reduced hydraulic power across all functions, with noticeably slower boom, arm, and bucket movements
• Engine over-revving without corresponding increases in hydraulic speed due to pump de-stroking issues
• Intermittent or continuous warning lamp illumination on the instrument cluster
• Erratic hydraulic response where functions work normally then suddenly lose power
• Increased fuel consumption as the system fails to efficiently match pump output to demand

Potential Causes

The most frequent causes of Code 14105-2 on used ZX350K-5G excavators include:

Solenoid valve wiring harness damage – particularly at routing points near the hydraulic pump where vibration and heat cause insulation breakdown. The harness between the main chassis connector and pump-mounted solenoid is especially vulnerable to chafing against frame members.

Failed pump solenoid valve coil – internal coil windings develop open circuits or short to ground, typically reading outside the specification range of 3-6 ohms resistance.

Corroded or loose electrical connectors – moisture intrusion at the pump solenoid connector (often located low on the machine where water spray occurs) causes high resistance connections.

ECM internal driver circuit failure – less common but possible in higher-hour machines where the control module's output transistors degrade.

Damaged wiring at bulkhead connectors – wire terminals backing out or corroding where the engine harness passes through firewall grommets.

How to Troubleshoot and Fix Code 14105-2

Step 1: Visual Inspection and Connector Examination Begin by locating the hydraulic pump solenoid valve on the main pump assembly (left side of engine). Disconnect the electrical connector and inspect for bent pins, corrosion, or moisture. On used excavators, check the entire wiring harness routing from ECM to solenoid for abrasion points, particularly where it contacts the engine block or frame rails. Clean connectors with electrical contact cleaner and apply dielectric grease.

Step 2: Solenoid Resistance Testing Using a digital multimeter, measure resistance across the solenoid valve terminals with the connector disconnected and ignition off. Specification should be 3-6 ohms. Also check for shorts to ground by measuring resistance between each terminal and the pump housing (should read infinite resistance/open circuit). Replace the solenoid valve if readings fall outside specifications.

Step 3: Circuit Voltage and Continuity Checks With ignition on but engine off, backprobe the ECM side of the disconnected solenoid connector. You should measure battery voltage (12V) on the power supply wire. Using Hitachi Dr.EX diagnostic software or an appropriate scan tool, command the solenoid valve to activate and verify the ECM is sending PWM signals (voltage should pulse between 0-12V). Check continuity between ECM connector pins and solenoid connector for broken wires.

Step 4: Advanced Diagnostics If wiring and solenoid test satisfactorily, the issue may be ECM-related. Inspect the ECM connectors for corrosion and verify ground circuits show less than 0.5 ohms resistance to chassis ground. For used machines, consider previous repair history—aftermarket harnesses or improper repairs often create intermittent fault conditions.

Disclaimer: This guide provides general troubleshooting information. Hydraulic and electrical system repairs should be performed by qualified technicians with proper training, tools, and access to manufacturer service documentation. Always consult the Hitachi ZX350K-5G service manual and follow lockout/tagout procedures before performing diagnostics.