What is Hitachi ZW310-5A Fault Code 111704-6?

Fault Code 111704-6 on the Hitachi ZW310-5A wheel loader indicates a pilot pressure sensor circuit malfunction, specifically a voltage signal that is out of the acceptable range or intermittently disconnected. This diagnostic trouble code (DTC) is generated by the machine's Electronic Control Module (ECM) when it detects abnormal voltage readings from the pilot pressure sensor, which monitors hydraulic pilot pressure critical for controlling attachment functions and travel operations.

The pilot pressure sensor is essential for this ZW310-5A model because it allows the ECM to regulate hydraulic flow precisely based on operator input through the joysticks and pedals. When this sensor circuit fails, the machine cannot accurately interpret pilot pressure commands, potentially leading to erratic hydraulic response or complete loss of certain functions. This code is particularly common in used excavators and wheel loaders where wiring harnesses have experienced years of vibration, exposure to hydraulic fluid contamination, and physical wear near moving components.

Common Symptoms

When fault code 111704-6 is active on your Hitachi ZW310-5A, you may experience:

• Hydraulic function sluggishness or complete loss of boom, bucket, or attachment control
• Warning light activation on the instrument cluster, often accompanied by audible alarm
• Reduced travel speed or derate mode engagement as a protective measure
• Intermittent loss of control that may return after machine restart or temperature changes
• Error message display on the monitor panel specifically referencing pilot or hydraulic system faults

Potential Causes

The most common technical reasons for code 111704-6 appearing on used Hitachi ZW310-5A machines include:

• Damaged or corroded wiring harness connections at the pilot pressure sensor connector (common wear point near cab pivot)
• Failed pilot pressure sensor due to internal component degradation or contamination exposure
• Broken or frayed wires in the harness routing between the sensor and ECM, especially at flex points
• Contaminated electrical connector pins from hydraulic oil seepage or moisture intrusion
• ECM internal fault (less common) affecting the sensor circuit voltage supply or ground
• Poor ground connection at sensor mounting location due to corrosion buildup on mounting surfaces

How to Troubleshoot and Fix Code 111704-6

Step 1: Visual Inspection and Connector Check Begin by locating the pilot pressure sensor on the hydraulic control valve assembly. Disconnect the electrical connector and inspect both the sensor pins and harness connector for corrosion, bent pins, hydraulic contamination, or moisture. On used excavators, this is the most frequent failure point. Clean connectors with electrical contact cleaner and apply dielectric grease before reconnecting.

Step 2: Sensor Voltage and Resistance Testing Using a digital multimeter (DMM), check the sensor's supply voltage with the ignition on (should read approximately 5 volts). Test sensor signal output voltage while manually applying pressure to verify proper voltage change (typically 0.5-4.5 volts range). Measure sensor resistance according to Hitachi specifications (usually 100-500 ohms depending on sensor type). Compare readings against manufacturer specifications in the service manual.

Step 3: Wiring Harness Continuity Check With the sensor disconnected, test continuity from the harness connector back to the ECM pins using wiring diagrams. Check for shorts to ground or power by measuring resistance to chassis ground (should read infinite/open). Inspect harness routing for rub points, abrasion, or heat damage, particularly near hydraulic lines and mechanical pivots common in aged machines.

Step 4: Component Replacement and Verification If testing confirms sensor failure, replace with a genuine Hitachi pilot pressure sensor or quality OEM equivalent. For harness damage, repair using proper soldering and heat-shrink techniques or replace the affected harness section. After repairs, clear the fault code using Hitachi diagnostic software (Dr.EX) or compatible scan tool, and perform a function test under load conditions to verify proper operation.

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Disclaimer: This guide provides general diagnostic information for Hitachi ZW310-5A fault code 111704-6. Always consult the official Hitachi service manual for your specific machine serial number and consider professional diagnosis by a certified heavy equipment technician for complex electrical or hydraulic issues.