What is Hitachi ZX170W-3 Fault Code 11403-3?

Fault Code 11403-3 on the Hitachi ZX170W-3 wheeled excavator indicates a malfunction in the hydraulic pump control system, specifically pointing to an abnormal signal from the pump pressure sensor or its associated circuit. This diagnostic trouble code (DTC) is triggered when the Electronic Control Module (ECM) detects a voltage reading outside the expected range from the main hydraulic pump pressure sensor, typically indicating either an open circuit, short circuit, or sensor degradation.

This code is critical for the ZX170W-3 because the hydraulic pump pressure feedback directly controls engine load management and automatic engine speed control. When this sensor fails, the ECM cannot properly match engine power to hydraulic demand, leading to inefficient operation and potential component damage.

Common Symptoms

When fault code 11403-3 is active on your Hitachi ZX170W-3, you may experience:

• Warning light illuminated on the instrument cluster with reduced hydraulic power output
• Erratic engine RPM fluctuations during hydraulic operations, especially under load
• Loss of automatic power boost function when operating multiple hydraulic circuits simultaneously
• Sluggish boom, arm, or bucket response despite normal engine operation
• Fuel consumption increase due to inefficient engine-pump coordination

Potential Causes

The most common technical reasons for code 11403-3 on used ZX170W-3 excavators include:

• Pressure sensor failure due to internal diaphragm fatigue or contamination from hydraulic fluid degradation
• Wiring harness damage at known rub points near the main pump assembly where vibration causes insulation wear
• Connector corrosion at the sensor plug, particularly on machines operated in wet or marine environments
• ECM internal circuit degradation in higher-hour machines (less common but possible beyond 8,000 hours)
• Hydraulic oil contamination causing sensor port blockage or false pressure readings
• Voltage supply issues from corroded ground connections on the sensor mounting bracket

How to Troubleshoot and Fix Code 11403-3

Step 1: Visual Inspection Begin by inspecting the hydraulic pump pressure sensor located on the main hydraulic pump assembly. Check the wiring harness for obvious damage, chafing, or oil contamination along its route from the sensor to the ECM. Pay special attention to areas where the harness passes near moving components or metal edges—a common failure point on used excavators.

Step 2: Electrical Testing Using a digital multimeter, check the sensor's supply voltage with the ignition on (should read approximately 5 volts). Then measure the signal wire voltage at idle—it should read between 0.5-4.5 volts depending on system pressure. Check resistance between the sensor ground and machine chassis (should be less than 1 ohm). Inspect connector terminals for corrosion or bent pins.

Step 3: Sensor and Circuit Validation If voltage readings are normal, connect Hitachi Dr.EX diagnostic software to read live sensor data and compare actual hydraulic pressure (using a mechanical gauge) to ECM-reported values. A variance greater than 10% indicates sensor replacement is needed. Before installing new parts on used equipment, thoroughly clean the sensor mounting port and apply anti-seize compound to prevent future corrosion issues.

Disclaimer: This guide provides general troubleshooting information. Always consult the Hitachi ZX170W-3 service manual and consider professional diagnostic assistance for complex electrical issues. Improper repairs may void warranties or cause additional damage.