Komatsu PC70-8 Fault Code DW45KA: Complete Diagnostic Guide

What is Komatsu PC70-8 Fault Code DW45KA?

Fault Code DW45KA indicates a malfunction in the hydraulic pump control system, specifically related to abnormal pressure sensor readings or pump displacement control circuit issues. This code is triggered when the Electronic Control Module (ECM) detects voltage irregularities or signal discrepancies from the hydraulic system's pressure monitoring components.

In the Komatsu PC70-8, this fault directly affects the machine's ability to regulate hydraulic flow and pressure efficiently. The pump control system is critical for optimizing fuel consumption and hydraulic performance across all functions—boom, arm, bucket, and swing operations. When DW45KA appears, the excavator may enter a protective derate mode to prevent catastrophic pump or hydraulic system damage.

Common Symptoms

When fault code DW45KA is active, operators typically experience:

• Hydraulic system warning light illuminated on the instrument panel
• Noticeably reduced hydraulic power across all functions, particularly during combined operations
• Sluggish response when operating multiple hydraulic circuits simultaneously
• Intermittent loss of hydraulic pressure during heavy load conditions
• ECM may limit engine RPM to protect the hydraulic pump from over-pressurization

Potential Causes

The most common technical causes for DW45KA on used PC70-8 excavators include:

• Hydraulic pressure sensor failure due to internal contamination or electrical degradation
• Damaged or corroded wiring harness connections at the pump control solenoid (common wear point near the pump mounting area)
• Failed pump displacement control solenoid valve causing erratic pressure regulation
• ECM voltage supply issues or poor ground connections
• Contaminated hydraulic oil affecting sensor accuracy and valve operation
• Worn harness routing clips allowing cable chafing against the pump housing (known issue on high-hour machines)

How to Troubleshoot and Fix Code DW45KA

Step 1: Visual Inspection Begin by inspecting the hydraulic pump area for obvious damage. Check all wiring harnesses running to the pump control solenoid and pressure sensors for abrasion, corrosion, or oil contamination. On used excavators, pay special attention to connector pins—clean with electrical contact cleaner if corrosion is present.

Step 2: Electrical Testing Using a digital multimeter, verify voltage supply to the pressure sensor (typically 5V reference) and check ground continuity. Test the sensor's output signal voltage under static conditions—compare readings against Komatsu specifications (usually 0.5-4.5V range). Inspect solenoid resistance (typically 10-30 ohms).

Step 3: Hydraulic System Check Test actual hydraulic pressure using a diagnostic pressure gauge at the pump test port. Compare readings with sensor output—discrepancies indicate sensor failure. Check hydraulic oil condition and filter status, as contamination can cause sensor malfunction.

Step 4: Component Replacement If diagnostics confirm sensor or solenoid failure, replace the faulty component using genuine Komatsu parts. Always apply dielectric grease to connectors during reassembly to prevent future corrosion.

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Disclaimer: This guide provides general diagnostic information. Always consult the official Komatsu service manual and consider professional technician assistance for complex repairs, especially on used equipment with unknown service history.