Hitachi ZW310-5A Fault Code 111702-6: Complete Diagnostic Guide

What is Hitachi ZW310-5A Fault Code 111702-6?

Fault Code 111702-6 on the Hitachi ZW310-5A wheel loader indicates a communication error or abnormal signal detected in the machine's hydraulic system control circuit, specifically related to the proportional solenoid valve feedback system. This code is generated when the Electronic Control Module (ECM) detects an inconsistency between the commanded hydraulic function and the actual response from the proportional valve position sensors.

This fault is critical because the ZW310-5A relies on precise electro-hydraulic control for loader functions including boom, bucket, and steering operations. When this code activates, the machine's hydraulic response becomes unpredictable, directly impacting productivity and operator safety. The proportional valve system uses variable electrical signals to control hydraulic flow rates, and any feedback disruption compromises this fine control.

Common Symptoms

When fault code 111702-6 is active, operators typically experience:

• Erratic hydraulic movements – jerky or inconsistent boom/bucket operation with sluggish response times
• Illuminated warning light on the instrument cluster, often accompanied by an audible alarm
• Reduced hydraulic function – loader arms may operate at reduced speed or power (derate mode)
• Intermittent loss of specific hydraulic functions – certain operations may fail completely while others work normally
• Error messages displayed on the digital monitor indicating hydraulic system malfunction

Potential Causes

The most common technical causes for this fault code on used ZW310-5A machines include:

• Damaged or corroded wiring harness at the proportional valve connector – known wear point where harness rubs against the hydraulic tank
• Failed proportional solenoid valve or internal coil resistance out of specification (typically 8-12 ohms nominal)
• Defective feedback sensor (potentiometer) within the valve assembly providing incorrect position data
• Corroded or loose electrical connectors at the valve or ECM due to water intrusion or age
• ECM software glitch requiring recalibration or update, particularly on older machines
• Low battery voltage or poor ground connections affecting signal quality to sensitive electronic components

How to Troubleshoot and Fix Code 111702-6

Step 1: Visual Inspection Begin with a thorough inspection of the proportional valve wiring harness located near the main hydraulic pump. On used excavators, check for harness chafing against metal brackets, melted insulation, or corroded connectors. Remove and inspect the valve connector for moisture, bent pins, or corrosion buildup. Clean contacts with electrical contact cleaner.

Step 2: Electrical Testing Using a digital multimeter, test the proportional solenoid coil resistance. Disconnect the valve connector and measure resistance across the solenoid terminals – readings should be 8-12 ohms. Check the feedback potentiometer by measuring resistance while manually moving the valve spool (if accessible); you should see smooth resistance changes from approximately 500 ohms to 4.5k ohms. Verify supply voltage is 12-14V at the connector with ignition on.

Step 3: Signal and Communication Check Connect Hitachi's Dr.EX diagnostic software or compatible scan tool to monitor live data from the proportional valve. Compare commanded values versus actual feedback readings. A discrepancy greater than 10% indicates sensor or valve failure. Check ground circuit continuity – resistance should be less than 1 ohm to chassis ground.

Step 4: Component Replacement If diagnostics confirm valve failure, replace the complete proportional solenoid valve assembly. For used machinery, always replace associated O-rings and seals simultaneously. After replacement, perform ECM recalibration using diagnostic software to ensure proper signal mapping. Clear codes and test all hydraulic functions under load.

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Disclaimer: This guide provides general diagnostic procedures. Hydraulic systems operate under extreme pressure and improper repairs can cause serious injury. Always consult qualified heavy equipment technicians and refer to official Hitachi service manuals for your specific machine serial number before performing repairs.