Komatsu PC110-8M0 Fault Code DXA8KB: Diagnosis and Repair Guide

What is Komatsu PC110-8M0 Fault Code DXA8KB?

Komatsu PC110-8M0 fault code DXA8KB indicates a communication error between the Engine Control Module (ECM) and the Hydraulic Control Module (HCM), specifically detecting an abnormal CAN bus signal transmission failure.

This diagnostic trouble code (DTC) is generated when the machine's Controller Area Network (CAN) experiences interrupted or corrupted data flow between critical control systems. The PC110-8M0 relies on constant ECM-HCM communication to coordinate engine performance with hydraulic demand, making this code particularly serious. When communication fails, the machine cannot properly synchronize engine output with hydraulic flow requirements, resulting in inefficient operation and potential protection mode activation. This fault is critical because it directly affects the integrated control system that distinguishes modern excavators from older mechanical models.

Common Symptoms

When DXA8KB is active on your Komatsu PC110-8M0, operators typically experience:

• Warning lamp illumination on the instrument cluster, often accompanied by a specific malfunction indicator light
• Reduced hydraulic responsiveness or sluggish arm/boom movement as the system enters derate mode
• Engine power limitation preventing the machine from reaching full RPM under load
• Intermittent loss of monitor display functions, with the LCD showing incomplete or frozen data
• Unexpected engine shutdown during operation, particularly when transitioning between idle and working speeds

Potential Causes

The most common technical failures triggering DXA8KB on used PC110-8M0 excavators include:

• CAN bus wiring harness damage at known wear points near the battery box and alongside the right-side track frame where cable routing creates friction against structural components
• Corroded or loose connector pins at the X3 ECM connector or the H1 hydraulic controller interface, particularly in machines exposed to coastal or high-humidity environments
• Failed termination resistor within the CAN network, typically a 120-ohm resistor that maintains signal integrity
• ECM or HCM internal fault due to voltage spikes from failing alternators or compromised grounding points
• Contaminated electrical connectors from hydraulic fluid leaks migrating along wire bundles toward control modules

How to Troubleshoot and Fix Code DXA8KB

Step 1: Visual Inspection and Connector Examination Begin by inspecting all CAN bus harness routing from the ECM (located under the operator's seat) to the HCM (mounted near the hydraulic pump). On used excavators, pay special attention to harness sections crossing movable joints or resting against sharp edges. Remove connector X3 at the ECM and connector H1 at the HCM, inspecting pins for corrosion (green oxidation), bent terminals, or hydraulic oil contamination. Clean connectors using electrical contact cleaner and apply dielectric grease before reassembly.

Step 2: CAN Bus Continuity and Resistance Testing Using a digital multimeter (DMM), measure resistance between CAN-High and CAN-Low terminals at the ECM connector with the harness disconnected. You should read approximately 60 ohms (two 120-ohm termination resistors in parallel). A reading of 120 ohms indicates one failed terminating resistor; infinite resistance suggests an open circuit in the wiring harness. Check each CAN wire individually for continuity from ECM to HCM—resistance should be less than 5 ohms per wire.

Step 3: Voltage Supply and Ground Verification With the key in the ON position (engine off), verify battery voltage (12-14V) is present at pin locations supplying both the ECM and HCM. Check all ground connections at G101 (ECM ground near battery) and G201 (HCM ground on hydraulic pump mounting bracket). Clean ground contact surfaces to bare metal and measure less than 0.5 ohms resistance to battery negative.

Step 4: Advanced Diagnostics with Komatsu KOMTRAX or Diagnostic Software Connect Komatsu diagnostic software (or compatible scan tool with Komatsu protocol capability) to monitor live CAN bus communication. Observe message traffic between controllers—missing or erratic data packets confirm communication failure. For used machines, perform a stored fault history review to identify intermittent patterns that suggest vibration-induced connector issues rather than hard component failures.

Critical Note for Used Excavators: Before replacing expensive control modules, methodically eliminate wiring and connector issues, as these represent 70-80% of DXA8KB faults in machines with over 3,000 operating hours.

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Disclaimer: This guide provides general troubleshooting information for experienced diesel mechanics. Always consult the official Komatsu PC110-8M0 service manual and consider professional diagnostic assistance for complex electrical issues. Improper repairs may result in additional damage or safety hazards.