Komatsu PC650-8R Fault Code DW45KB: Complete Diagnostic Guide

What is Komatsu PC650-8R Fault Code DW45KB?

Fault Code DW45KB indicates a communication error or malfunction in the machine monitoring system's data transmission network, specifically related to the controller area network (CAN) communication between the engine controller (ECM) and the monitor controller.

This diagnostic trouble code (DTC) signals that the ECM (Engine Control Module) and the machine's monitor controller are experiencing interrupted or corrupted data exchange. The CAN bus system is critical for the PC650-8R's integrated control architecture, as it allows real-time communication between multiple electronic control units. When this communication fails, the machine cannot properly coordinate engine performance with hydraulic systems, potentially leading to reduced operational efficiency and safety concerns.

For the PC650-8R's Komatsu SAA6D140E-7 engine, maintaining proper CAN communication is essential for emissions control, fuel injection timing, and hydraulic load sensing.

Common Symptoms

• Warning lights illuminated on the monitor panel, specifically communication error indicators or check engine lights
• Intermittent or complete loss of engine parameter displays (RPM, coolant temperature, fuel level) on the cab monitor
• Engine operating in derate mode or limp-home mode with reduced power output
• Erratic hydraulic response or inconsistent implement control due to communication delays
• Inability to access diagnostic information through the standard monitor interface

Potential Causes

Wiring harness damage is the most common culprit in used PC650-8R excavators, particularly where harnesses route near the engine mounting points or swing bearing, causing abrasion and wire exposure.

Corroded or loose connectors at the ECM or monitor controller, especially in machines operated in coastal or high-humidity environments.

Failed monitor controller or ECM internal communication circuit failure, more prevalent in high-hour machines (8,000+ hours).

Voltage irregularities from failing alternators or weak batteries affecting CAN bus voltage levels (should maintain 2.5V differential).

Previous repair damage where aftermarket harnesses or improper splicing created resistance or short circuits in the CAN network.

How to Troubleshoot and Fix Code DW45KB

Step 1: Visual Inspection Begin with a thorough inspection of all wiring harnesses between the ECM (located near the engine) and the monitor controller (cab-mounted). Look specifically for chafing points where harnesses contact frame members, heat shields, or hydraulic lines. On used excavators, check connector pins for corrosion, bent terminals, or moisture intrusion using a flashlight and inspection mirror.

Step 2: Electrical Testing Using a digital multimeter, verify CAN bus voltage at both the ECM and monitor controller connectors. With ignition on, measure between CAN-High and CAN-Low terminals—you should read approximately 2.5V differential. Check for proper termination resistance (should read 60 ohms) across the CAN network. Use Komatsu's KOMTRAX diagnostic software or a compatible scan tool to monitor real-time communication status.

Step 3: Component Isolation Disconnect the monitor controller and check if the ECM generates additional codes. If DW45KB clears, the monitor controller may be faulty. Inspect ground connections at both controllers—corrosion at ground points is common in older machines. Before replacing expensive controllers, swap connectors with known-good components if available, or test harness continuity wire-by-wire.

Step 4: Repair and Verification Replace damaged harness sections using OEM-spec wire and heat-shrink connectors rated for vibration and temperature extremes. Apply dielectric grease to all reconnected terminals. Clear codes and perform a complete operational test under load.

---

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