Hitachi ZW310-5A Fault Code 111703-11: Meaning and Fix Guide

What is Hitachi ZW310-5A Fault Code 111703-11?

Fault code 111703-11 on the Hitachi ZW310-5A wheel loader indicates a hydraulic pump solenoid valve circuit malfunction, specifically related to the load sensing (LS) control system. This diagnostic trouble code (DTC) signals that the Engine Control Module (ECM) has detected an abnormal electrical signal from the hydraulic pump's proportional solenoid valve, which regulates flow and pressure based on machine demand.

This code is critical because the ZW310-5A relies on precise load-sensing hydraulics to optimize fuel efficiency and machine responsiveness. When this circuit fails, the hydraulic system cannot properly modulate pump output, leading to reduced performance, increased fuel consumption, and potential hydraulic system damage. The proportional solenoid valve receives pulse-width modulated (PWM) signals from the ECM to adjust hydraulic pressure—any interruption in this communication triggers code 111703-11.

Common Symptoms

When fault code 111703-11 is active, operators typically experience:

• Reduced hydraulic response across all functions (boom, bucket, and auxiliary circuits)
• Illuminated warning lamp on the instrument panel with possible derate mode activation
• Erratic loader arm movements or inconsistent lift speeds under varying loads
• Increased fuel consumption due to the pump running at maximum displacement regardless of demand
• Unusual whining or cavitation noises from the hydraulic pump area during operation

Potential Causes

The most common technical reasons for this fault code on used Hitachi ZW310-5A loaders include:

• Faulty proportional solenoid valve due to internal coil deterioration or contaminated hydraulic fluid causing sticking
• Damaged wiring harness between the ECM and solenoid valve, particularly at known rub points near the pump mounting bracket
• Corroded or loose electrical connectors at the solenoid valve (common on machines operating in wet or corrosive environments)
• ECM power supply issues including blown fuses or compromised ground connections
• Hydraulic contamination causing mechanical restriction in the solenoid valve spool movement
• Previous repair attempts with incorrect solenoid resistance values or aftermarket components

How to Troubleshoot and Fix Code 111703-11

Step 1: Visual and Electrical Inspection Begin by disconnecting the battery negative terminal. Locate the hydraulic pump solenoid valve on the main pump assembly (driver's side of engine compartment). Inspect the electrical connector for corrosion, bent pins, or moisture intrusion. Check the wiring harness along its entire length for chafing, especially where it passes near the cooling fan shroud—a known wear point on ZW310-5A models.

Step 2: Solenoid Resistance Testing Using a digital multimeter (DMM), measure the solenoid coil resistance with the connector disconnected. Specification for this solenoid typically ranges between 3-7 ohms at room temperature. Values outside this range indicate coil failure. Also perform a diode test to check for internal short circuits to ground.

Step 3: Circuit Voltage and Signal Testing Reconnect the solenoid and backprobe the connector using the multimeter. With ignition on (engine off), verify 12-14 volts battery voltage at the power supply terminal. Using an oscilloscope or PWM-capable meter, confirm the ECM is sending proper pulse-width modulated signals (typically 200-500 Hz frequency). Absence of PWM signals indicates potential ECM programming issues or internal ECM failure.

Step 4: Used Machine-Specific Checks For used excavators, inspect hydraulic fluid quality—contaminated oil can cause valve sticking even with proper electrical signals. Check for previous aftermarket repairs using non-OEM solenoids with incorrect specifications. Examine all chassis ground points near the ECM mounting area for rust or loose connections, which commonly cause intermittent faults on older machines.

Step 5: Component Replacement and Verification If testing confirms solenoid failure, replace with genuine Hitachi parts (part number specific to ZW310-5A model year). Clear fault codes using Hitachi diagnostic software (Dr.EX) or equivalent. Perform a hydraulic system calibration and test under load conditions to verify proper pump response.

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Disclaimer: This guide provides general diagnostic procedures for fault code 111703-11. Hydraulic and electrical systems operate under high pressure and voltage. Always consult the official Hitachi ZW310-5A service manual and consider professional diagnosis for complex electrical issues or if unfamiliar with heavy equipment systems.