What is Komatsu PC210LC-10 Fault Code DHA4KA?

Fault Code DHA4KA on the Komatsu PC210LC-10 excavator indicates a communication error between the Engine Controller (ECM) and the Hydraulic Controller (PMC - Pump Control Module). This diagnostic trouble code signals that the controllers cannot exchange data properly over the CAN (Controller Area Network) bus system.

This code is critical for the PC210LC-10's performance because the ECM and PMC must constantly communicate to optimize engine power output with hydraulic demand. When communication fails, the machine's intelligent load-sensing system cannot coordinate properly, resulting in reduced efficiency and potential automatic derating. The Komatsu KOMTRAX system uses this specific alphanumeric format (DHA-series codes) to identify network communication faults within the machine's electronic architecture.

Common Symptoms

When fault code DHA4KA is active, operators typically experience:

• Engine warning light illuminated on the monitor panel, often accompanied by a specific communication error message
• Reduced hydraulic performance with sluggish boom, arm, or bucket response due to safety mode activation
• Engine derating where maximum RPM is limited to protect components during uncertain operating conditions
• Intermittent loss of monitor display functions, including loss of hydraulic temperature readings or flow data
• Abnormal engine speed fluctuations when demanding hydraulic functions under load

Potential Causes

The most common technical causes for DHA4KA on used PC210LC-10 excavators include:

• CAN bus wiring harness damage between the engine compartment and main valve/pump area—particularly at flex points near the swing bearing where harnesses experience repeated movement
• Corroded or loose connector pins at the ECM (located behind the operator cab) or PMC (mounted near the hydraulic pumps)
• Faulty ECM or PMC module, often due to moisture intrusion in machines with compromised seals or those operated in high-humidity environments
• Poor grounding connections at chassis ground points, especially common in excavators with 5,000+ operating hours
• CAN bus termination resistor failure within either controller module
• Voltage supply issues to either controller caused by deteriorated main wiring harness or battery cable connections

How to Troubleshoot and Fix Code DHA4KA

Step 1: Visual Inspection of Wiring Harnesses Begin by thoroughly inspecting the CAN bus harness running from the ECM to the PMC. On used excavators, pay special attention to areas where the harness passes through the swing bearing area and along the right-hand side frame rail. Look for abrasion marks, cut insulation, or evidence of rubbing against metal surfaces. Check all connector boots for cracks or moisture intrusion.

Step 2: Connector and Ground Point Inspection Disconnect the ECM connector (typically a 48-pin or dual connector setup) and the PMC connector at the pump control module. Inspect each pin for corrosion, bent contacts, or green oxidation—extremely common in machines over 3-5 years old. Use electrical contact cleaner and verify connector lock mechanisms function properly. Check all chassis ground points (especially G101 and G102 on this model) for tightness and clean metal-to-metal contact.

Step 3: CAN Bus Resistance Testing Using a digital multimeter, measure the resistance between CAN-H and CAN-L terminals at the ECM connector (with harness disconnected). You should read approximately 60 ohms, indicating proper termination resistors in the network. A reading of 120 ohms suggests one termination resistor has failed; infinite resistance indicates an open circuit in the harness.

Step 4: Voltage Supply Verification With the ignition key ON (engine off), verify that both the ECM and PMC are receiving proper 24V supply voltage at their respective power pins. Check the Komatsu service manual for specific pin locations. Low voltage (below 22V) suggests battery, alternator, or main power harness issues common in used equipment.

Step 5: Diagnostic Software Analysis Connect Komatsu diagnostic software (KTEC or equivalent dealer-level tool) to read live data streams from both controllers. Monitor whether the software can communicate with each module independently. If one controller shows "no communication" while the other responds, the non-communicating module is likely faulty. For used excavators, reprogram both controllers with the latest software versions, as outdated firmware can cause intermittent communication errors.

Step 6: Component Replacement If all wiring, grounds, and voltage checks pass, suspect a failed controller. On used machines, the PMC fails more frequently than the ECM due to heat exposure near hydraulic components. Always verify part numbers match your machine's serial number range before ordering replacement controllers, as Komatsu used different hardware revisions throughout PC210LC-10 production.

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Disclaimer: This guide provides general troubleshooting information for experienced diesel mechanics. Always consult the official Komatsu service manual for your specific machine serial number and software version. If unfamiliar with high-voltage electrical systems or CAN bus diagnostics, contact an authorized Komatsu dealer or certified heavy equipment technician to prevent damage to sensitive electronic components.