## What is Hitachi ZX670LC-5A Fault Code 13303-2?

**Fault Code 13303-2 on the Hitachi ZX670LC-5A indicates a communication error between the Engine Control Module (ECM) and the Hydraulic Control Module (HCM), specifically a data transmission timeout or CAN bus communication failure.** This diagnostic trouble code (DTC) triggers when the **ECM** fails to receive expected signal responses from the **HCM** within the manufacturer's predetermined time parameters, typically within 500-1000 milliseconds.

This code is critical for the ZX670LC-5A because this excavator relies on integrated **electronic control systems** that coordinate engine output with hydraulic demand. When communication breaks down between these modules, the machine cannot properly match engine RPM to hydraulic flow requirements, leading to reduced performance and potential automatic derate modes to protect components.

## Common Symptoms

When fault code 13303-2 is active on your ZX670LC-5A, operators typically experience:

- **Master warning light** illuminated on the instrument cluster with reduced engine power notification
- **Hydraulic system responsiveness** significantly diminished, with sluggish boom, arm, or bucket movements
- **Engine derate** to approximately 70-80% of normal output, limiting travel speed and cycle times
- **Intermittent loss** of hydraulic functions during operation, particularly under load conditions
- **Error messages** displayed on the multi-function monitor indicating "Controller Communication Error"

## Potential Causes

The most common technical reasons for code 13303-2 on used ZX670LC-5A excavators include:

- **CAN bus wiring harness** damage, particularly at known wear points near the swing bearing and along the boom base where flexing occurs repeatedly
- **Corroded or loose connector pins** at the **HCM** or **ECM** connections, especially on machines operating in coastal or high-moisture environments
- **ECM or HCM internal failure**, more common in machines exceeding 8,000-10,000 operating hours
- **Ground circuit degradation** affecting module communication integrity due to rust or loose chassis ground points
- **Voltage supply issues** to either control module from failing relays, aged wiring, or battery/charging system problems
- **Aftermarket installation errors** if hydraulic attachments were added with improper CAN integration

## How to Troubleshoot and Fix Code 13303-2

**Step 1: Initial Inspection and Data Retrieval**
Connect **Hitachi Dr.EX diagnostic software** or a compatible CAN diagnostic tool to retrieve freeze frame data and active/pending codes. Document when the fault occurs (startup, during operation, or intermittently). Inspect all visible **wiring harnesses** between the ECM (located near the engine) and HCM (typically mounted on the main valve) for physical damage, burns, or chafing—particularly critical on used excavators.

**Step 2: Electrical Testing**
Using a **digital multimeter**, check **CAN-High and CAN-Low** circuit resistance between the ECM and HCM connectors. Proper resistance should measure approximately 60 ohms across the terminated bus. Verify **supply voltage** to both modules (should read 24V DC ±1V with key on). Inspect all **ground connections** at module mounting points; clean and tighten as needed. For used machines, pay special attention to **connector terminals**—remove, inspect for green corrosion, and apply dielectric grease.

**Step 3: Component Isolation and Replacement**
Disconnect the **HCM connector** and inspect pins for bending, corrosion, or moisture intrusion (common in excavators with 5,000+ hours). Swap suspect modules with known-good units if available for diagnostic confirmation. If harness damage is found at **flex points** near articulation areas, repair using OEM-spec shielded CAN cable with proper termination and protective sleeving. Clear codes, operate machine through full working range, and monitor for fault reoccurrence.

**Professional Disclaimer:** This guide provides general troubleshooting direction for experienced technicians. Always consult the Hitachi ZX670LC-5A service manual for torque specifications, exact wiring diagrams, and safety procedures. Complex ECM/HCM issues may require factory-level diagnostics and software updates best performed by authorized Hitachi service centers.