What is Hitachi ZX330-5G Fault Code 13304-2?

Fault Code 13304-2 on the Hitachi ZX330-5G excavator indicates a malfunction in the Engine Control Module (ECM) communication circuit, specifically a signal abnormality or intermittent connection between the ECM and the machine's main controller. This code is part of Hitachi's proprietary diagnostic system and points to a breakdown in the CAN bus communication network that allows the engine management system to exchange data with hydraulic controls, instrument cluster, and monitoring systems.

This fault is critical because the ZX330-5G relies on continuous communication between controllers to optimize fuel injection timing, hydraulic response, and emissions control. When this circuit fails, the excavator may enter a protective derate mode or experience erratic performance, directly impacting productivity on job sites.

Common Symptoms

• Warning light activation on the instrument panel, specifically the engine malfunction or system error indicator
• Reduced engine power or automatic derate to lower RPM ranges, limiting digging force and travel speed
• Intermittent loss of monitor display data, including fuel consumption, temperature readings, or hydraulic pressure gauges
• Erratic hydraulic response during combined operations (swing + boom movement), caused by communication delays
• Engine starting issues or extended cranking time, particularly after the machine has been sitting idle

Potential Causes

On used Hitachi ZX330-5G excavators, this fault commonly stems from age-related deterioration rather than component failure. The most frequent causes include:

• Corroded or loose connector pins at the ECM harness connection point, especially on machines operating in wet or coastal environments
• Damaged CAN bus wiring due to harness chafing against the engine block or frame rails near the battery box—a known wear point on this model
• Failed terminating resistor in the communication network, causing signal reflection and data errors
• ECM internal fault or corrupted software, particularly on machines with 8,000+ operating hours
• Voltage fluctuations from aging battery cables or poor grounding at the ECM mounting bracket

How to Troubleshoot and Fix Code 13304-2

Step 1: Connect Hitachi Dr.EX diagnostic software or compatible scan tool to retrieve freeze frame data and confirm the fault is active. Check communication status between all controllers on the network.

Step 2: Perform a visual harness inspection focusing on the main engine harness from the ECM to the junction box near the hydraulic pump. Look for abraded insulation, pinched wires at cable ties, or green corrosion at connector bodies. On used machines, check where harnesses cross metal edges.

Step 3: Test CAN High and CAN Low circuit resistance using a digital multimeter. Between the two CAN bus lines at the ECM connector (typically pins 23 and 24), you should measure approximately 60 ohms with the key off, indicating proper terminating resistor function.

Step 4: Inspect and clean all grounding points for the ECM. Remove, wire-brush, and reinstall ground connections at the engine block and frame. Apply dielectric grease to prevent future corrosion.

Step 5: If all physical checks pass, perform an ECM voltage supply test. Verify battery voltage (12.5-14.5V) at the ECM power pins with key on. Low voltage indicates battery or alternator issues common in older equipment.

Step 6: Replace damaged sections of the communication harness rather than individual wires when possible, ensuring proper shielding is maintained. For used excavators, consider proactive replacement of the entire engine-to-cab harness if the machine exceeds 10,000 hours.

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Disclaimer: This guide provides general diagnostic information. Always consult the official Hitachi service manual for your specific machine serial number and software version. Complex electrical diagnostics should be performed by certified technicians with proper diagnostic equipment.