Komatsu PC850-8R Fault Code DW43KB: Complete Diagnostic Guide

What is Komatsu PC850-8R Fault Code DW43KB?

Fault Code DW43KB indicates a communication error or abnormal signal detected in the machine monitoring system's CAN (Controller Area Network) bus, specifically related to data transmission between the main controller and peripheral monitoring modules.

This diagnostic trouble code (DTC) is triggered when the Engine Control Module (ECM) or Machine Controller detects inconsistent, missing, or corrupted data packets from connected sensors or control units on the communication network. For the PC850-8R, this is critical because the CAN bus coordinates essential functions including engine performance parameters, hydraulic system monitoring, and operator display information. When communication breaks down, the machine cannot properly regulate performance or provide accurate operational feedback.

Common Symptoms

When DW43KB is active on your Komatsu PC850-8R, operators typically experience:

• Warning lights illuminated on the monitor panel, often accompanied by error messages indicating communication faults
• Intermittent or complete loss of gauge readings (fuel level, hydraulic temperature, engine RPM)
• Erratic behavior of the machine monitor display, including flickering screens or frozen readouts
• Potential engine derate or reduced hydraulic response as the system enters failsafe mode
• Multiple simultaneous fault codes appearing due to cascading communication failures across systems

Potential Causes

The DW43KB code in used PC850-8R excavators commonly stems from:

• Corroded or damaged CAN bus connectors, particularly at harness junction points near the engine bay or cab mounting areas where vibration and moisture exposure are highest
• Frayed or pinched wiring harnesses at known rub points, especially where cables route through the swing bearing area or along the boom
• Failed termination resistors on the CAN network causing signal reflection and data corruption
• Faulty machine monitor unit or display module with degraded internal communication circuits
• ECM or controller software corruption requiring reprogramming or module replacement
• Voltage irregularities from aging batteries or failing alternators affecting network stability

How to Troubleshoot and Fix Code DW43KB

Step 1: Visual Inspection Begin with a thorough physical examination of all wiring harnesses connected to the machine monitor and main controllers. Focus on connectors behind the cab display, engine compartment junction boxes, and harness routing through articulation points. Look for green corrosion on pins, cracked connector housings, or obvious wire damage.

Step 2: Electrical Testing Using a digital multimeter, verify proper CAN bus voltage (typically 2.5V nominal with 1-4V signal range). Check termination resistance between CAN-High and CAN-Low lines at network endpoints—should read approximately 60 ohms with key off. Test ground continuity at all controller mounting points, as poor grounds frequently cause communication issues in used excavators.

Step 3: Diagnostic Software Analysis Connect Komatsu KOMTRAX or compatible diagnostic software to read detailed fault data, including which specific module is failing to communicate. Monitor live data streams to identify intermittent connection drops. Clear codes and perform a CAN bus integrity test if available in your diagnostic tool.

Step 4: Component Isolation Systematically disconnect peripheral modules (starting with non-critical accessories) to isolate the faulty component. If the code clears when a specific module is disconnected, inspect that unit's connector and wiring for damage before condemning the component itself.

For used excavators, always prioritize inspecting harness wear points and connector corrosion before replacing expensive electronic modules, as environmental degradation is the leading cause of communication faults in aging heavy equipment.

---

Disclaimer: This guide provides general troubleshooting information. Always consult Komatsu service manuals and qualified technicians for your specific machine. Improper diagnosis may lead to unnecessary repairs or safety hazards.