Komatsu PC70-8 Fault Code DW45KB: Complete Diagnostic Guide

What is Komatsu PC70-8 Fault Code DW45KB?

Fault Code DW45KB indicates a communication error or abnormal signal between the machine's Engine Control Module (ECM) and the hydraulic system controller. This code specifically relates to data transmission failures within the Controller Area Network (CAN) bus system that coordinates engine performance with hydraulic functions.

In the Komatsu PC70-8, this fault affects the integrated control system that manages fuel injection timing, hydraulic pump output, and overall machine efficiency. When communication breaks down between these critical controllers, the excavator cannot properly coordinate engine power with hydraulic demand, leading to reduced performance and potential safety concerns. This is particularly critical in the PC70-8 model, which relies on precise electronic coordination for its compact yet powerful hydraulic system.

Common Symptoms

When DW45KB is active, operators typically experience:

• Warning light illumination on the instrument panel, often accompanied by a diagnostic trouble code display
• Reduced hydraulic response or sluggish boom/arm movements due to improper engine-hydraulic coordination
• Engine derate mode where maximum RPM is limited to protect the machine from uncoordinated operation
• Intermittent loss of auxiliary functions such as swing speed control or attachment hydraulics
• Erratic engine behavior including unexpected RPM fluctuations during loaded operations

Potential Causes

The most common technical causes for DW45KB in used PC70-8 excavators include:

• CAN bus wiring harness damage from rubbing against the frame near the engine mounting points (known wear location on this model)
• Corroded or loose connector pins at the ECM or hydraulic controller, especially in machines exposed to moisture
• Failed termination resistor within the CAN network causing signal reflection and data corruption
• ECM or hydraulic controller internal failure due to age-related component degradation
• Voltage supply issues from deteriorated ground connections or failing alternator output affecting controller stability

How to Troubleshoot and Fix Code DW45KB

Step 1: Visual Inspection Begin by thoroughly inspecting all wiring harnesses between the ECM (located near the engine) and the hydraulic controller (typically mounted under the operator cab). On used excavators, check for harness chafing where cables pass through bulkheads or near moving components. Examine all connector pins for corrosion, bent terminals, or moisture intrusion.

Step 2: Electrical Testing Using a digital multimeter, verify CAN-High and CAN-Low voltage at both controllers. You should measure approximately 2.5V on each line with the key on, engine off. Check for proper 120-ohm termination resistance across the CAN bus lines. Inspect ground connections at both controllers, ensuring less than 0.5 ohms resistance to chassis ground.

Step 3: Advanced Diagnostics Connect Komatsu KOMTRAX diagnostic software or a compatible CAN bus analyzer to monitor real-time communication. Look for missing data packets or error frames. For used machines, pay special attention to intermittent connection issues caused by vibration-loosened terminals—wiggle test all connectors while monitoring communication.

Step 4: Component Replacement If diagnostics isolate a failed component, replace the wiring harness, controller, or termination resistor as needed. Always apply dielectric grease to connectors during reassembly to prevent future corrosion.

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Disclaimer: This guide provides general troubleshooting information. Always consult the official Komatsu service manual for your specific machine serial number and consider professional diagnostic assistance for complex electrical issues.