Komatsu PC70-8 Fault Code DA22KK: Complete Diagnostic Guide

What is Komatsu PC70-8 Fault Code DA22KK?

Fault Code DA22KK indicates a malfunction in the hydraulic pump control system, specifically related to the pump discharge pressure sensor circuit or abnormal pressure readings detected by the Electronic Control Module (ECM).

This code triggers when the ECM detects voltage signals outside the normal operating range from the main pump pressure sensor, or when actual hydraulic pressure readings don't match expected values during operation. For the PC70-8 model, this is critical because the ECM uses these pressure readings to optimize fuel efficiency and regulate hydraulic flow to attachments. Ignoring this code can lead to reduced digging force, erratic boom/arm movements, and potential damage to the hydraulic pump assembly.

Common Symptoms

When DA22KK is active, operators typically experience:

• Warning light illuminated on the instrument panel with reduced hydraulic power
• Noticeably slower cycle times during digging, lifting, or swing operations
• Intermittent loss of hydraulic pressure, especially under heavy loads
• Engine derate mode activation in severe cases, limiting RPM to protect the system
• Unusual whining or cavitation noises from the main hydraulic pump

Potential Causes

The most common technical reasons for DA22KK on used PC70-8 excavators include:

• Pressure sensor failure due to internal diaphragm wear or contamination from hydraulic fluid breakdown
• Damaged or corroded wiring harness connections at the sensor plug (common rub point near the pump mounting bracket)
• Hydraulic fluid contamination causing erratic pressure readings or sensor port blockage
• ECM calibration drift or software glitches in older machines with high operating hours
• Actual hydraulic system problems: worn pump components, relief valve malfunction, or internal leakage

How to Troubleshoot and Fix Code DA22KK

Step 1: Visual Inspection Begin by inspecting the pressure sensor located on the main hydraulic pump body. Check for oil leaks, damaged connectors, or corroded pins. On used excavators, examine the wiring harness routing for wear points where it contacts the frame or pump housing.

Step 2: Electrical Testing Using a multimeter, measure sensor supply voltage (should be 5V ±0.25V) and signal output voltage with the engine running. Compare readings against Komatsu specifications in the service manual. Check harness resistance between the sensor and ECM connector—readings above 5 ohms indicate wiring issues.

Step 3: Hydraulic System Verification Install a calibrated pressure gauge at the test port to verify actual system pressure matches sensor readings. If discrepancies exist but electrical tests pass, replace the pressure sensor. If actual pressure is low, investigate pump wear or relief valve settings.

Step 4: Component Replacement For used machines, always clean connector terminals with electrical contact cleaner before replacing sensors. After repairs, clear codes using Komatsu diagnostic software (KOMTRAX or compatible scan tool) and perform a function test under load.

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