What is Komatsu PC110-8M0 Fault Code DHSJMA?

Fault Code DHSJMA on the Komatsu PC110-8M0 excavator indicates a hydraulic system communication error between the machine's main controller (ECM) and the hydraulic pump control module. This diagnostic trouble code (DTC) is triggered when the Electronic Control Module (ECM) detects an abnormal signal or loss of communication with the hydraulic pump's electronic control unit, which regulates pump displacement and system pressure.

This code is particularly critical for the PC110-8M0 because this model relies on precise electronic feedback to optimize fuel efficiency and hydraulic performance. When communication fails, the machine may enter a protective derate mode to prevent damage to the hydraulic system, significantly reducing operational productivity.

Common Symptoms

When fault code DHSJMA is active, operators typically experience:

• Illuminated warning light on the instrument panel, often accompanied by a wrench or diagnostic icon
• Reduced hydraulic power across all functions (boom, bucket, swing) as the system enters safe mode
• Sluggish or erratic response from hydraulic controls, particularly during combined operations
• Intermittent loss of auxiliary hydraulic functions, such as breaker or grapple attachments
• Engine may continue running normally, but with limited hydraulic capability

Potential Causes

The most common technical causes for DHSJMA on used PC110-8M0 excavators include:

• Corroded or damaged wiring harness connectors between the ECM and hydraulic pump controller (check near the swing bearing where harnesses experience frequent flexing)
• Failed hydraulic pump solenoid or internal control valve position sensor
• Low voltage supply to the pump control module due to aging battery or poor ground connections
• ECM software corruption or outdated firmware requiring reprogramming
• Physical damage to CAN bus communication lines, especially on machines with previous collision or rollover history
• Moisture intrusion into sealed connectors from failed gaskets or damaged wire loom protection

How to Troubleshoot and Fix Code DHSJMA

Step 1: Visual Inspection Begin by thoroughly inspecting the wiring harness running from the main ECM (located under the operator's cab) to the hydraulic pump control module. On used excavators, focus on areas where the harness passes through the swing bearing assembly and near the engine firewall—these are common rub points on the PC110-8M0. Look for chafed insulation, crushed wires, or corroded connectors with green/white oxidation.

Step 2: Electrical Testing Using a digital multimeter, verify the power supply voltage at the hydraulic pump controller connector (should read 12-14V with key on, engine off). Check the ground circuit resistance—it should be below 0.5 ohms. Test the CAN bus communication lines (typically yellow and green wires) for continuity and proper termination resistance (approximately 60 ohms between CAN-High and CAN-Low).

Step 3: Diagnostic Software Analysis Connect Komatsu KOMTRAX diagnostic software or a compatible scanner to retrieve freeze frame data. Check for additional simultaneous codes that might indicate whether the issue originates from the ECM or pump controller. Clear the code and perform an active test of the hydraulic solenoid valve through the software to verify command response.

Step 4: Component-Level Diagnosis If electrical systems test normal, suspect the hydraulic pump control module itself. On used machines, internal solder joint failures or capacitor degradation are common after 5,000+ operating hours. Before replacing expensive components, swap the suspect module with a known-good unit if available, or send for professional bench testing.

Critical Note for Used Excavators: Always check service history for previous hydraulic system repairs. Aftermarket or incorrectly programmed replacement parts may cause persistent communication errors even when physically functional.

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Disclaimer: This guide provides general troubleshooting information. Always consult the official Komatsu service manual for your specific machine serial number, and consider professional diagnostic assistance for complex electrical issues. Improper repairs may void warranties or create safety hazards.