What is Doosan Excavator Fault Code E000678-03?

Fault Code E000678-03 indicates a communication error or data inconsistency within the Doosan excavator's CAN (Controller Area Network) bus system, specifically related to abnormal message transmission between the main controller (ECM) and peripheral control modules. This diagnostic trouble code (DTC) signals that the Electronic Control Module (ECM) has detected corrupted, missing, or out-of-range data packets from connected systems such as the hydraulic control unit, instrument cluster, or engine monitoring sensors.

This fault is critical for Doosan excavators because the CAN bus serves as the central nervous system for machine operations. When communication breaks down, the ECM may trigger protective derate modes, limiting engine power or hydraulic functions to prevent potential damage. For used excavators, this code often surfaces due to age-related wiring degradation or connector corrosion.

Common Symptoms

• Intermittent or complete loss of instrument panel displays, including engine RPM, temperature, or hydraulic pressure readings
• Engine derate mode activation, resulting in reduced power output or restricted operating speed
• Erratic hydraulic system behavior, such as sluggish boom/arm movements or inconsistent swing functions
• Multiple warning lights illuminating simultaneously on the operator dashboard without clear patterns
• Difficulty starting the machine or unexpected engine shutdowns during operation

Potential Causes

The most common technical reasons for Code E000678-03 in used Doosan excavators include:

• Damaged or corroded CAN bus wiring harness, particularly at pinch points near the swing bearing or along the boom where cables experience constant flexing
• Faulty ECM or peripheral control module with internal communication failures
• Loose or oxidized electrical connectors at the main wiring harness junction boxes, especially in machines exposed to moisture
• Low system voltage from aging batteries or failing alternators causing intermittent communication dropouts
• Software incompatibility issues if ECM or controller modules have been replaced with mismatched firmware versions
• Physical damage to termination resistors on the CAN bus network endpoints

How to Troubleshoot and Fix Code E000678-03

Step 1: Visual Harness Inspection Begin by thoroughly inspecting the main wiring harness from the ECM to all control modules. Focus on known wear points where harnesses contact metal edges near the cab mounting, swing circle, and engine compartment. Look for chafed insulation, pinched wires, or green corrosion on connectors. On used excavators, these friction points often cause intermittent shorts.

Step 2: Connector and Voltage Testing Disconnect and clean all CAN bus connectors using electrical contact cleaner. Check for bent pins or moisture intrusion. Using a digital multimeter, verify battery voltage remains above 24V (or 12V depending on system) under load. Test CAN-High and CAN-Low wire resistance between modules—readings should show 60 ohms between the two lines with termination resistors intact.

Step 3: Diagnostic Software Analysis Connect Doosan diagnostic software (DMS-5 or equivalent) to access live CAN bus data. Monitor real-time communication status between modules to identify which specific component is dropping messages. Check for stored freeze frame data indicating environmental conditions when the fault occurred. Verify all control modules show correct firmware versions and update if mismatches exist.

Step 4: Component Isolation Testing If wiring checks pass, systematically disconnect peripheral modules one at a time while monitoring for fault clearing. This isolates failing components. For used machines, hydraulic control units and instrument clusters are common failure points due to vibration fatigue.

Disclaimer: This guide provides general troubleshooting information. Always consult the official Doosan service manual for your specific model and seek professional diagnostic assistance when dealing with complex electrical systems or if you lack proper diagnostic tools.