Hitachi ZW220 Fault Code 11920-2: Complete Diagnostic Guide

What is Hitachi ZW220 Fault Code 11920-2?

Fault Code 11920-2 indicates a communication error or abnormal signal from the hydraulic pump control system, specifically related to the pump pressure sensor circuit or the electronic control unit (ECU) communication failure. This code is part of Hitachi's proprietary diagnostic system and signals that the machine's computer cannot properly read or communicate with critical hydraulic pressure monitoring components.

This fault is particularly critical for the ZW220 wheel loader because the hydraulic pump control system directly affects loader arm speed, bucket breakout force, and overall machine responsiveness. When this code activates, the ECM (Engine Control Module) may limit hydraulic functions to prevent damage, significantly reducing productivity and potentially causing unsafe operating conditions.

Common Symptoms

When fault code 11920-2 is active, operators typically experience:

• Reduced hydraulic power or sluggish loader arm and bucket movements
• Warning light illumination on the instrument cluster (typically a hydraulic system warning)
• Intermittent loss of hydraulic functions, especially during high-demand operations
• Error messages displayed on the digital monitor indicating hydraulic system faults
• Derated engine performance as the ECM enters protective mode to prevent system damage

Potential Causes

The most common technical causes for this fault code on used ZW220 machines include:

• Faulty hydraulic pump pressure sensor due to internal wear or contamination from hydraulic fluid degradation
• Damaged wiring harness between the pressure sensor and ECM, particularly at flex points near the pump mounting area
• Corroded or loose electrical connectors at the sensor or ECM interface—common in machines with high operating hours
• ECM internal communication failure or corrupted software requiring reprogramming
• Hydraulic fluid contamination causing sensor membrane damage or erratic readings
• Ground circuit issues specific to the hydraulic control system wiring

How to Troubleshoot and Fix Code 11920-2

Step 1: Visual Inspection Begin by inspecting the hydraulic pump pressure sensor location (typically mounted on the main hydraulic pump). Check for physical damage, oil leaks, or connector corrosion. On used excavators, pay special attention to harness wear points where cables contact the frame or move with the pump assembly.

Step 2: Electrical Testing Using a digital multimeter, check the sensor's supply voltage (typically 5V reference) and ground circuit continuity. Measure sensor output voltage at idle and under load—consult Hitachi service manual specifications. Test harness resistance between the sensor connector and ECM pins; readings above 5 ohms indicate wiring degradation.

Step 3: Component Testing Disconnect the pressure sensor and test its resistance across terminals (typically 200-500 ohms depending on temperature). Use Hitachi Dr.EX diagnostic software to monitor real-time sensor data and verify ECM communication. Clear codes and perform a functional test. If codes return immediately, suspect ECU communication failure rather than sensor issues.

Step 4: Repair or Replace For used machines, clean all connector terminals with electrical contact cleaner before replacing components. Replace the pressure sensor if readings are out of specification. Repair or replace damaged harness sections, ensuring proper routing away from heat and friction points. If all circuits test correctly but the fault persists, ECM reprogramming or replacement may be necessary.

---

Disclaimer: This guide provides general diagnostic information. Always consult the official Hitachi service manual for your specific machine serial number and consider professional diagnostic services for complex electrical issues.