Komatsu PC220-8 Fault Code DWK0KB: Complete Diagnostic Guide

What is Komatsu PC220-8 Fault Code DWK0KB?

Fault code DWK0KB on the Komatsu PC220-8 indicates a communication error between the engine controller (ECM) and the hydraulic pump controller (HPC), specifically related to load-sensing data transmission failure. This code triggers when the ECM cannot properly receive or validate hydraulic load demand signals from the HPC via the CAN bus network, disrupting the critical engine-to-hydraulic power matching system.

This fault is particularly critical for the PC220-8 because this model relies on advanced proportional control between engine output and hydraulic demand. When communication fails, the excavator loses its ability to optimize fuel consumption and hydraulic performance, potentially causing significant operational inefficiency and component stress.

Common Symptoms

When code DWK0KB is active, operators typically experience:

• Engine hunting or surging during hydraulic operations, especially when multiple functions are used simultaneously
• Reduced hydraulic power across all circuits, with noticeably slower cycle times on boom, arm, and bucket functions
• Warning light activation on the monitor panel, often accompanied by a "Check Engine" or system fault indicator
• Increased fuel consumption due to inability to match engine RPM to actual hydraulic demand
• Intermittent performance issues that may improve or worsen with machine temperature changes

Potential Causes

The most common technical causes for DWK0KB in used PC220-8 excavators include:

• CAN bus wiring harness damage at known rub points near the hydraulic pump mounting bracket and behind the cab (common wear area on machines with 4,000+ hours)
• Corroded or moisture-contaminated connectors on the HPC controller located under the operator platform
• Failed hydraulic pump controller module, particularly in machines operating in high-heat or dusty environments
• ECM software corruption or outdated firmware versions requiring reflash procedures
• Intermittent ground circuit failures at chassis grounding points G101 or G102 (prone to corrosion)
• Damaged CAN bus termination resistors (120-ohm resistors at network endpoints)

How to Troubleshoot and Fix Code DWK0KB

Step 1: Initial Diagnostic Scan Connect Komatsu KOMTRAX diagnostic software or compatible scan tool to the 9-pin diagnostic port. Check for additional active codes that might indicate primary failures. Record all freeze frame data showing engine RPM and hydraulic pressure at fault occurrence.

Step 2: Physical Harness Inspection Inspect the CAN bus harness routing from the ECM (left side of engine block) to the HPC (mounted on hydraulic pump). On used excavators, carefully check the harness section passing through the rotating center joint—this is a critical wear point. Look for abraded insulation, pinched wires, or previous repair attempts using incorrect wire gauge.

Step 3: Connector and Voltage Testing Disconnect the 20-pin connector at the HPC. Inspect pins for corrosion, bent terminals, or moisture intrusion. Using a digital multimeter, verify CAN High and CAN Low voltage levels (should read approximately 2.5V with key on, engine off). Check for proper 120-ohm resistance across CAN High and CAN Low terminals when network terminators are intact.

Step 4: Controller Functionality Test With harness verified, reconnect all components and monitor live data during operation. If communication remains intermittent, perform a controller swap test if available. Replace the HPC if erratic data transmission continues with confirmed good wiring. For persistent issues after component replacement, an ECM reflash using latest Komatsu firmware may resolve software-related communication protocol errors.

---

Disclaimer: This guide provides general diagnostic procedures for experienced technicians. Always consult the official Komatsu PC220-8 service manual and consider professional diagnostic assistance for complex electrical issues. Improper troubleshooting can cause additional system damage.