What is Komatsu PC210-10 Fault Code DHA4KA?

Fault Code DHA4KA on the Komatsu PC210-10 excavator indicates a communication error between the engine controller (ECM) and the hydraulic system controller (HSC), specifically related to the hydraulic pump control signal malfunction. This code triggers when the Engine Control Module (ECM) detects an abnormal or missing data signal from the Hydraulic System Controller, which manages pump displacement and flow control based on engine load conditions.

This communication fault is critical because the PC210-10 utilizes Komatsu's advanced Komtrax Plus closed-loop hydraulic system, where the ECM and HSC must constantly exchange data to optimize fuel efficiency and hydraulic performance. When this communication breaks down, the machine cannot properly match hydraulic pump output to operational demands, resulting in reduced performance and potential component stress.

Common Symptoms

When fault code DHA4KA is active, operators typically experience:

• Hydraulic system derate with noticeably slower boom, arm, or bucket movements, particularly under load
• Engine power limitation as the ECM enters a protective mode, preventing the machine from reaching full RPM
• Intermittent or constant warning light on the multi-information display showing hydraulic system errors
• Erratic hydraulic response where implement speeds vary unpredictably during operation
• Increased fuel consumption due to inefficient pump control and engine-hydraulic mismatch

Potential Causes

The DHA4KA code on used PC210-10 excavators typically stems from:

• Corroded or loose connector pins at the HSC module (located near the hydraulic pump), especially on machines with 3,000+ operating hours
• Damaged CAN bus wiring harness between ECM and HSC, commonly caused by rubbing against the engine mounting bracket near the fuel filter assembly
• Failing Hydraulic System Controller itself, particularly in machines operating in high-temperature or high-vibration environments
• ECM software version mismatch after controller replacements or incomplete firmware updates
• Poor ground connections at the HSC mounting bolts, which can oxidize on older machines stored outdoors

How to Troubleshoot and Fix Code DHA4KA

Step 1: Visual Inspection and Connection Check Begin by accessing the HSC module located on the main hydraulic pump. Disconnect the main 20-pin connector and carefully inspect all pins for corrosion, bent contacts, or moisture. Clean contacts with electrical contact cleaner and apply dielectric grease. On used excavators, check the harness routing for signs of wear, particularly where it passes near the engine block.

Step 2: CAN Bus Communication Testing Using Komatsu's KDPF diagnostic software or a compatible CAN bus analyzer, check for proper communication voltage between ECM pins 38/39 (CAN-H and CAN-L). You should measure approximately 2.5V on each line with ignition on, engine off. Test termination resistance between CAN-H and CAN-L; it should read 60 ohms. If readings deviate significantly, trace the harness for breaks or shorts.

Step 3: Controller and Ground Verification Verify the HSC ground circuit by measuring resistance from the controller case to battery negative; it should be less than 1 ohm. Remove, clean, and reinstall ground connections at mounting bolts. If all electrical checks pass but the code persists, the HSC may require replacement (Komatsu part #7835-46-1004). Before replacing controllers, verify ECM software version matches HSC compatibility using KDPF software—mismatched versions are common in used machines with replacement parts.

Step 4: Clear Code and Operational Test After repairs, clear codes using diagnostic software and perform a complete operational cycle test, monitoring real-time data between ECM and HSC during varied hydraulic loads.

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Disclaimer: This guide provides general diagnostic information for fault code DHA4KA. Always consult the official Komatsu PC210-10 service manual and consider professional diagnostic assistance for complex electrical issues. Improper troubleshooting can damage expensive electronic components.