What is Komatsu PC110-8M0 Fault Code DWJ0KB?

Fault Code DWJ0KB on the Komatsu PC110-8M0 excavator indicates a communication error between the Engine Control Module (ECM) and the Monitor Controller, specifically related to CAN (Controller Area Network) bus data transmission failure. This diagnostic trouble code triggers when the main computer systems cannot properly exchange critical operational data, affecting the machine's ability to monitor engine parameters and hydraulic system performance.

This code is particularly critical for the PC110-8M0 because this mid-sized excavator relies on integrated electronic controls to optimize fuel efficiency and coordinate between the engine management system and the hydraulic pump controller. When communication breaks down, the machine may enter a protective derate mode to prevent potential damage from unmonitored operating conditions.

Common Symptoms

• Warning lamp illumination on the monitor panel, often accompanied by a "communication error" message or check engine light
• Engine power derate or limitation to idle speed, preventing normal operation until the fault is resolved
• Intermittent gauge failures, including loss of coolant temperature, fuel level, or hydraulic oil temperature readings on the display
• Erratic engine RPM response or inability to properly adjust throttle settings through the control panel
• Hydraulic system performance issues, particularly sluggish response times due to lack of coordinated control signals

Potential Causes

The most common technical failures triggering DWJ0KB on used PC110-8M0 excavators include:

• CAN bus wiring harness damage at known rub points near the swing bearing and boom cylinder mounting areas where cable flexing causes insulation wear
• Corroded or loose connector pins at the ECM or Monitor Controller harness plugs, especially in machines exposed to wet environments
• Faulty termination resistors on the CAN network, typically located at the ECM and display unit endpoints
• ECM or Monitor Controller internal failures, more common in high-hour machines (above 8,000 operating hours)
• Voltage supply issues from deteriorated battery cables or failing alternator output affecting module power quality
• Aftermarket component interference from improperly installed telematics devices or non-OEM accessories tapped into the CAN network

How to Troubleshoot and Fix Code DWJ0KB

Step 1: Visual Harness Inspection Begin by physically inspecting the main wiring harness running from the engine bay to the operator cab. Focus on areas where the harness passes through the swing circle and along the boom base—these are known wear points on the PC110-8M0. Look for abraded insulation, pinched wires, or oil contamination on connectors. Clean all ECM and Monitor Controller connector pins with electrical contact cleaner and verify secure connections.

Step 2: CAN Network Electrical Testing Using a digital multimeter, measure the resistance between CAN High and CAN Low terminals at the ECM connector with the key off and all modules disconnected. You should read approximately 60 ohms (indicating proper termination resistors). Then check for 120 ohms to ground on each line individually. Any significant deviation suggests damaged termination resistors or shorted wiring requiring replacement.

Step 3: Power Supply Verification Verify that the ECM and Monitor Controller are receiving clean voltage. With the key on, check for 24V DC at the power supply pins (consult the PC110-8M0 wiring diagram for exact terminal locations). Voltage below 22V or fluctuations greater than 1V indicate battery, alternator, or ground connection problems that must be addressed before proceeding.

Step 4: Diagnostic Software Analysis Connect Komatsu KOMTRAX or a compatible diagnostic tool to read live CAN bus data traffic. Monitor whether both modules are transmitting. If one module shows no communication, that specific controller likely requires replacement. For used excavators, consider that ECM software updates may be available from Komatsu that resolve known communication bugs in older firmware versions.

Step 5: Component Replacement Procedure If harness and electrical tests pass but the fault persists, replace the termination resistors first (least expensive solution). If unsuccessful, substitute the Monitor Controller before the ECM, as display units fail more frequently. When replacing components on used machines, always verify that replacement parts match the serial number range and software version of your specific PC110-8M0 variant.

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Disclaimer: This guide provides general troubleshooting information for experienced technicians. Always consult the official Komatsu PC110-8M0 service manual for exact specifications and safety procedures. Complex electrical diagnostics should be performed by certified Komatsu technicians with proper diagnostic equipment. Improper repairs may void warranties or create safety hazards.