Komatsu PC200LC-8 Fault Code DW43KA: Complete Diagnostic Guide

What is Komatsu PC200LC-8 Fault Code DW43KA?

Fault Code DW43KA indicates a malfunction in the engine controller (ECM) communication circuit, specifically related to the CAN (Controller Area Network) bus system on the Komatsu PC200LC-8 excavator. This code triggers when the Engine Control Module (ECM) detects intermittent or lost communication with other critical machine controllers.

The CAN bus is the digital nervous system of modern excavators, allowing the engine controller, hydraulic controller, and monitor panel to exchange real-time data. On the PC200LC-8 with the SAA6D107E-1 engine, this communication network is essential for coordinating engine power output with hydraulic demand. When communication breaks down, the machine cannot properly regulate performance, potentially causing unexpected derate conditions or safety system activation.

Common Symptoms

When DW43KA is active, operators typically experience:

• Warning light illumination on the monitor panel, often accompanied by an audible alarm
• Intermittent loss of monitor display functions, including missing RPM, coolant temperature, or fuel level readings
• Unexpected engine derate or power reduction, especially under load
• Hydraulic system irregularities, such as sluggish response or inconsistent swing/boom speed
• Multiple fault codes appearing simultaneously, as the communication failure affects various systems

Potential Causes

The most common technical failures triggering DW43KA on used PC200LC-8 machines include:

• CAN bus harness damage at known rub points near the battery box and along the engine-to-cab routing path
• Corroded or loose connector pins at the ECM harness (particularly the 58-pin main connector)
• Failed termination resistor within the CAN network (120-ohm resistor failure)
• ECM internal circuit degradation, more common in machines exceeding 8,000 operating hours
• Voltage supply issues from the main relay or battery connection affecting controller stability
• Water intrusion into the ECM enclosure or harness connectors from damaged seals

How to Troubleshoot and Fix Code DW43KA

Step 1: Visual Harness Inspection Begin with a thorough physical examination of all CAN bus wiring from the ECM to the monitor and hydraulic controller. On used excavators, check the harness routing behind the battery box where vibration commonly causes insulation wear. Inspect all connector terminals for green corrosion, bent pins, or moisture. Clean connectors with electrical contact cleaner and apply dielectric grease.

Step 2: CAN Bus Resistance Testing Using a digital multimeter, disconnect power and measure resistance across the CAN-High and CAN-Low terminals at the ECM connector. You should read approximately 60 ohms (two 120-ohm termination resistors in parallel). A reading significantly higher indicates an open circuit; infinity suggests complete network failure. Consult the Komatsu service manual wiring diagrams for precise terminal locations.

Step 3: Voltage Supply Verification With the key switch ON (engine off), verify the ECM receives proper battery voltage (24V nominal) at the power supply pins. Check the main relay operation and measure voltage drop across ground connections—excessive resistance (above 0.2V) indicates corroded ground points requiring cleaning and re-termination.

Step 4: Advanced Diagnostics with KOMTRAX or Komatsu Diagnostic Software Connect Komatsu diagnostic software to monitor live CAN bus traffic and identify which specific controller is dropping communication. This pinpoints whether the fault originates from the ECM, monitor, or hydraulic controller, preventing unnecessary part replacement on used machines.

Critical for Used Excavators: Before replacing the ECM (a costly repair), verify all harness integrity and connector conditions. Machines operating in harsh environments often develop multiple corrosion points that mimic controller failure.

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Disclaimer: This guide provides general diagnostic information. Always consult the official Komatsu service manual for your specific machine serial number and seek professional assistance from certified Komatsu technicians for complex electrical diagnostics and repairs.