Choosing the Right Diagnostic Tools for Hitachi Excavators

[MikePhua]

Hitachi’s Diagnostic Landscape and Equipment Evolution
Hitachi Construction Machinery, founded in 1970 as a division of Hitachi Ltd., has long been recognized for its precision hydraulic systems and electronic control integration. Excavators like the EX120-2 represent a transitional era where analog hydraulics began merging with digital fault monitoring. These machines feature basic onboard computers capable of storing fault codes and sensor data, but accessing that information requires compatible diagnostic tools.
While newer Hitachi models use CAN-based systems and proprietary software suites, older units like the EX120-2 rely on simpler protocols and connectors. This creates a challenge for owners seeking low-cost, reliable diagnostic solutions without access to dealer-level equipment.
Dr.ZX and MPDr Software Comparison
Two common software platforms used for Hitachi diagnostics are Dr.ZX and MPDr. Dr.ZX originated as a palm-based tool and later evolved into a PC-compatible version. It interfaces with the excavator’s control unit via a serial or USB adapter and can read fault codes, monitor sensor values, and display basic system status.
MPDr, on the other hand, is a more advanced diagnostic suite developed for Hitachi’s internal use. It supports broader functionality, including real-time sensor graphs, actuator testing, and firmware updates. However, compatibility between MPDr and third-party cables like those used with Dr.ZX is inconsistent.
Terminology annotation:

• Fault Code: A numeric or alphanumeric identifier stored by the machine’s control unit indicating a malfunction.
  
• Sensor Value Monitoring: The ability to read live data from pressure, temperature, or position sensors.
  
• COM Port: A communication interface on a computer used to connect serial devices.
  
• TX/RX Pins: Transmit and receive terminals used in serial communication protocols.
  

Cable Compatibility and Connector Challenges
One recurring issue is the physical compatibility of diagnostic cables. The Dr.ZX adapter often requires inversion—rotating the connector 180 degrees—to align with the excavator’s diagnostic port. This is due to non-standard pin layouts in older Hitachi models. Users have found that connecting only the right-side pins enables fault code reading via the PVC LED, while the left-side pins may correspond to TX and RX lines needed for full data exchange.
Recommendations for cable setup:

• Use a USB-to-serial adapter with adjustable COM port settings
  
• Confirm pinout using a multimeter or manufacturer schematic
  
• Avoid forcing connectors; misalignment can damage terminals
  
• Label modified cables to prevent future confusion
  

Software Installation and Virus Risks
Many low-cost diagnostic kits ship with outdated or corrupted software CDs. In some cases, download links provided by sellers contain malware or trigger antivirus warnings. This poses a serious risk to users attempting to install diagnostic tools on their work laptops.
To mitigate this:

• Use a dedicated laptop with no sensitive data for diagnostic software
  
• Scan all downloads with multiple antivirus engines before installation
  
• Request checksum verification from the seller to confirm file integrity
  
• Consider using virtual machines to isolate potentially harmful programs
  

In one case, a user received a Dr.ZX software link that was flagged for containing a Trojan. After switching to MPDr and manually configuring the COM port, they were able to connect to the excavator and retrieve error code 22, indicating “Pump Control Not Normal.”
Interpreting Fault Codes and Sensor Behavior
Hitachi fault codes are often cryptic and require interpretation using service manuals or dealer documentation. Code 22, for example, suggests a problem with pump control logic—possibly due to a faulty pressure sensor, wiring issue, or control valve malfunction.
To troubleshoot:

• Verify sensor voltage and resistance using a multimeter
  
• Inspect wiring harnesses for abrasion or corrosion
  
• Check hydraulic pressure manually to confirm sensor accuracy
  
• Reset fault codes after repairs to confirm resolution
  

Sensor monitoring is especially valuable when diagnosing intermittent faults. Real-time data can reveal voltage drops, erratic readings, or temperature spikes that static codes may not capture.
Alternative Diagnostic Platforms
For users frustrated with Dr.ZX and MPDr limitations, platforms like Jaltest Off-Highway offer broader compatibility. Jaltest supports multiple brands and can connect to electronic control modules (ECMs) across various equipment types. While more expensive, it provides dealer-level diagnostics and is backed by regular updates.
Other options include:

• TEXA Off-Highway diagnostic systems
  
• Nexiq USB-Link with custom software
  
• OEM tools from Hitachi dealers (often restricted to authorized service)
  

Conclusion
Diagnosing faults on Hitachi excavators like the EX120-2 requires a blend of hardware compatibility, software reliability, and electrical understanding. While tools like Dr.ZX offer a low-cost entry point, users must navigate connector quirks, software risks, and limited functionality. MPDr provides deeper insight but may require cable modifications and driver troubleshooting. For those seeking robust diagnostics, investing in multi-brand platforms or dealer support may be the most efficient path. In the end, understanding the machine’s language—whether through blinking LEDs or serial data—is key to keeping it running strong.