Komatsu PC210-10 Fault Code DHSJMA: Complete Diagnostic Guide

What is Komatsu PC210-10 Fault Code DHSJMA?

Fault Code DHSJMA indicates a communication error between the excavator's Engine Control Module (ECM) and the hydraulic system's Display Control Unit (DCU). This specific code signals that the CAN bus communication network has experienced a data transmission failure or timeout event between these critical control systems.

In the Komatsu PC210-10, this fault affects the integrated KOMTRAX telematics system and the machine's ability to properly coordinate engine performance with hydraulic demand. The ECM and DCU constantly exchange operational data—including engine load, hydraulic pressure requests, and temperature readings—to optimize fuel efficiency and machine responsiveness. When communication breaks down, the excavator may enter a protective derate mode to prevent potential damage from uncoordinated system operation.

This is particularly critical for the PC210-10's advanced hydraulic matching system, which relies on real-time data exchange to deliver the model's characteristic fuel efficiency and smooth combined operations.

Common Symptoms

• Amber warning light illuminated on the instrument cluster with communication error message displayed
• Reduced engine power or automatic derate to lower RPM ranges (typically limiting to 1,500-1,800 RPM)
• Sluggish hydraulic response, especially during combined functions like swing-and-boom operations
• Intermittent gauge failures or flickering display readings on the monitor panel
• KOMTRAX connectivity issues preventing remote monitoring or data upload

Potential Causes

The DHSJMA code typically stems from issues common in used excavators with significant operating hours:

• CAN bus wiring harness damage at known rub points near the upper structure/undercarriage junction where cable flex is constant
• Corroded or loose connector pins at the 38-pin ECM connector (C1) or the 24-pin DCU connector located behind the cab
• Failed termination resistor in the CAN network (120-ohm resistor failure disrupts entire communication network)
• ECM or DCU software corruption due to voltage spikes or incomplete software updates
• Damaged shielding on CAN-H and CAN-L data wires, allowing electrical interference from starter motor or alternator
• Moisture intrusion in junction boxes, particularly in machines operated in wet or coastal environments

How to Troubleshoot and Fix Code DHSJMA

Step 1: Visual Harness Inspection Begin with a thorough physical inspection of the main wiring harness running from the engine bay to the cab. Focus on the harness routing near the swing bearing, where repeated rotation creates wear points. Check for abraded insulation, pinched wires, or signs of heat damage. On used excavators, look specifically for previous repair attempts using incorrect wire gauge or improper splice techniques.

Step 2: Connector and Pin Testing Disconnect the ECM connector C1 and DCU connector (refer to service manual section 3-147 for exact locations). Inspect pins for corrosion, bent contacts, or backed-out terminals. Use electrical contact cleaner and compressed air. Measure terminal resistance between connector housing and each pin—any reading below 10 megohms indicates contamination requiring connector replacement.

Step 3: CAN Bus Electrical Testing Using a digital multimeter with the ignition OFF, measure resistance between CAN-H and CAN-L terminals at the ECM connector. You should read approximately 60 ohms (two 120-ohm terminating resistors in parallel). A reading of 120 ohms indicates one failed terminator; infinite resistance means open circuit or complete network failure.

Step 4: Dynamic Communication Testing Connect Komatsu diagnostic software (KETC) or compatible scan tool. Monitor live CAN bus traffic while operating the machine. Intermittent communication dropouts visible in the data stream indicate vibration-related harness failures. Check voltage levels: CAN-H should read 2.5-3.5V and CAN-L should read 1.5-2.5V during active communication.

Step 5: Software and Ground Verification Verify ECM and DCU software versions match compatibility charts in technical bulletin SEBR-9999. Update if necessary using only genuine Komatsu software files. Finally, test chassis ground resistance—critical ground point G301 (located on engine block) to battery negative should read less than 0.5 ohms.

For used excavators, replacing the entire engine-to-cab harness often proves more cost-effective than chasing intermittent failures in aged wiring.

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Disclaimer: This guide provides general diagnostic information. Always consult the official Komatsu PC210-10 service manual and consider professional diagnosis for complex electrical issues. Improper troubleshooting can damage electronic control modules.