Komatsu PC210-10 Fault Code DHS9MA: Complete Diagnostic Guide

What is Komatsu PC210-10 Fault Code DHS9MA?

Fault code DHS9MA on the Komatsu PC210-10 indicates a communication error between the main hydraulic pump controller and the engine ECM (Engine Control Module). This code specifically signals that the KOMTRAX telematics system has detected an abnormal data transmission failure in the CAN (Controller Area Network) bus communication line that links hydraulic and engine control systems.

This fault is critical for the PC210-10 because proper communication between these systems ensures optimal fuel efficiency, hydraulic response, and power matching. When this communication breaks down, the excavator cannot properly coordinate engine output with hydraulic demand, potentially leading to reduced performance and increased fuel consumption.

Common Symptoms

When fault code DHS9MA is active, operators typically experience:

• Warning light illumination on the monitor panel, often accompanied by a communication error message
• Reduced hydraulic response or sluggish movement during combined operations (swing with boom/arm)
• Engine power limitations where the machine feels underpowered despite normal RPM
• Intermittent monitor display failures showing incorrect or frozen operational data
• Increased fuel consumption due to improper engine-hydraulic matching

Potential Causes

The most common technical causes for DHS9MA on used PC210-10 excavators include:

• CAN bus wiring harness damage near the engine-to-cab routing points where harness rubs against frame members
• Corroded or loose connector pins at the ECM connector (particularly pins 18 and 19 on the 48-pin connector)
• Failed hydraulic pump controller PCB due to moisture intrusion or age-related capacitor failure
• ECM internal communication module failure (less common, but possible in high-hour machines)
• Grounding issues at chassis ground points G301 or G302, especially if corrosion is present
• Damaged termination resistor in the CAN bus network (120-ohm resistor failure)

How to Troubleshoot and Fix Code DHS9MA

Step 1: Visual Inspection of Wiring Harnesses Begin by thoroughly inspecting the main wiring harness running from the engine compartment to the cab. On used excavators, check for harness wear at common rub points: near the engine mount brackets, along the right-side frame rail, and where the harness enters the cab floor. Look for abraded insulation, crushed wires, or signs of previous repairs with electrical tape.

Step 2: Connector and Ground Point Verification Disconnect the ECM 48-pin connector and inspect for green corrosion, bent pins, or moisture. Pay special attention to CAN-High (pin 18) and CAN-Low (pin 19) terminals. Clean with electrical contact cleaner if needed. Verify chassis ground points G301 (behind cab) and G302 (engine block) show less than 0.5 ohms resistance to battery negative using a quality digital multimeter.

Step 3: CAN Bus Communication Testing Using Komatsu diagnostic software (KOMTRAX-PLUS or equivalent), monitor live CAN bus traffic. Check for communication packet loss or abnormal voltage levels. With ignition on, engine off, measure voltage between CAN-High and CAN-Low wires—should read approximately 2.5V differential. Check termination resistance across CAN-High to CAN-Low at the ECM connector—should measure 60 ohms (two 120-ohm resistors in parallel).

Step 4: Component Isolation If wiring and grounds test correctly, isolate the fault between the pump controller and ECM. Swap the pump controller with a known-good unit if available, or send the existing controller for bench testing. For used excavators with over 8,000 hours, consider ECM capacitor degradation as a potential cause requiring ECM replacement or professional refurbishment.

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