What is Komatsu PC800LC-8R Fault Code E0EDA2RMC?

Fault Code E0EDA2RMC indicates a communication error between the Engine Control Module (ECM) and the Hydraulic Control Module (HCM) on the Komatsu PC800LC-8R excavator. This diagnostic trouble code specifically points to a CAN bus communication failure or data transmission interruption within the machine's integrated control network.

The PC800LC-8R relies on continuous data exchange between the ECM and HCM to optimize engine performance, hydraulic flow, and fuel efficiency. When communication breaks down, the machine cannot properly coordinate engine output with hydraulic demand, leading to reduced operational efficiency and potential safety concerns. This code is particularly critical because it affects the machine's ability to perform coordinated functions like simultaneous boom and swing operations.

Common Symptoms

• Warning lights illuminate on the monitor panel, specifically the engine and hydraulic system indicators
• Noticeable power derate or reduced engine RPM, limiting maximum operating speed
• Sluggish hydraulic response during combined operations, especially under heavy loads
• Intermittent loss of auxiliary hydraulic functions or attachment control
• Error messages displayed on the multi-function monitor indicating communication faults

Potential Causes

The most common causes for E0EDA2RMC on used PC800LC-8R excavators include:

• CAN bus wiring harness damage from rubbing against the engine block or hydraulic pump mounting brackets—a known wear point on this model
• Corroded or loose connector pins at the ECM or HCM connection points, especially in machines operating in wet or coastal environments
• Failed termination resistors on the CAN bus network causing signal reflection
• ECM or HCM internal failure, more common in high-hour machines (8,000+ hours)
• Water intrusion into control module housings due to deteriorated seals on older units
• Voltage irregularities from aging battery cables or poor grounding connections

How to Troubleshoot and Fix Code E0EDA2RMC

Step 1: Connect Komatsu KOMTRAX diagnostic software or compatible scan tool to retrieve freeze frame data and verify code status. Check if the fault is active or historical.

Step 2: Perform a visual inspection of the CAN bus harness routing between the ECM (located behind the operator cab) and HCM (mounted near the hydraulic pump). Look for chafing, cuts, or heat damage. On used excavators, pay special attention to harness routing near moving components.

Step 3: Inspect all connector terminals at both modules. Clean contacts with electrical contact cleaner and check for bent pins or corrosion. Measure resistance between CAN-High and CAN-Low wires—should read approximately 60 ohms with modules disconnected.

Step 4: Using a multimeter, verify proper voltage supply to both modules (typically 24V DC). Check ground connections for resistance below 0.5 ohms.

Step 5: Test termination resistors at network endpoints. Replace if readings deviate from 120 ohms specification.

Step 6: If wiring and connections test properly, perform module-specific diagnostics using manufacturer software to isolate ECM versus HCM failure.

For used excavators, always address harness wear and connector corrosion before replacing expensive control modules, as these account for 70% of communication faults.

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Disclaimer: This guide provides general troubleshooting information. Always consult qualified Komatsu technicians and refer to official service manuals for your specific machine serial number before performing repairs.