What is Komatsu PC110-8M0 Fault Code DHSHMA?

Fault Code DHSHMA on the Komatsu PC110-8M0 excavator indicates a hydraulic system malfunction related to the main control valve or hydraulic pressure sensor communication error. This code typically signals that the machine's electronic control module (ECM) has detected abnormal hydraulic pressure readings or a failure in the data transmission between the hydraulic monitoring system and the main controller.

This code is critical for the PC110-8M0 because proper hydraulic pressure regulation directly affects attachment performance, swing functions, and overall operational safety. When the ECM cannot accurately monitor hydraulic pressures, the machine may enter a protective derate mode to prevent catastrophic component damage or unsafe operating conditions.

Common Symptoms

When fault code DHSHMA is active, operators typically experience:

• Hydraulic function sluggishness or complete loss of certain operations (boom, arm, or bucket movements may become unresponsive or extremely slow)
• Warning lights illuminated on the instrument cluster, specifically the hydraulic system alert indicator
• Intermittent machine derate where engine power is automatically reduced to protect the hydraulic system
• Erratic attachment performance with inconsistent speed or force during digging, lifting, or swinging operations
• Audible warning alarms from the cabin monitoring system when hydraulic pressure thresholds are exceeded or not met

Potential Causes

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

• Hydraulic pressure sensor failure due to internal wear, contamination, or electrical component degradation common in machines with 4,000+ operating hours
• Damaged wiring harness near the main control valve—a known rub point on this model where the harness passes over the swing bearing assembly
• Corroded electrical connectors at the pressure sensor interface, particularly on machines operated in high-moisture or coastal environments
• Main control valve solenoid malfunction preventing proper pressure regulation signal transmission
• ECM communication errors caused by voltage irregularities or software glitches in older firmware versions
• Contaminated hydraulic fluid affecting sensor accuracy and creating false pressure readings

How to Troubleshoot and Fix Code DHSHMA

Step 1: Initial Diagnostic Scan Connect Komatsu-specific diagnostic software (KOMTRAX compatible tool or KDW—Komatsu Diagnostic Wizard) to the machine's diagnostic port. Record all active and inactive fault codes, freeze frame data, and current hydraulic pressure sensor readings. Compare sensor values against factory specifications (typically 280-320 bar for main system pressure on PC110-8M0).

Step 2: Physical Inspection of Sensors and Wiring For used excavators, visually inspect the hydraulic pressure sensor mounted on the main control valve block. Check for oil leaks, physical damage, or loose mounting. Critically examine the wiring harness from the sensor to the ECM, paying special attention to the swing bearing area where harness chafing is common. Look for frayed wires, exposed copper, or burnt insulation.

Step 3: Electrical Testing Using a digital multimeter, perform resistance checks on the pressure sensor (typically 250-350 ohms at 20°C for this model). Check voltage supply at the sensor connector—should read 5V ± 0.5V with key on, engine off. Test continuity through the entire harness circuit to identify any open circuits or high-resistance connections.

Step 4: Connector and Ground Verification Clean all electrical connectors with contact cleaner, checking specifically for corrosion on pins. Verify ground circuits have less than 0.2 ohms resistance to chassis. On used machines, corrosion at ground points near the hydraulic tank is particularly common and can cause intermittent communication errors.

Step 5: Component Replacement and Calibration If testing confirms sensor failure, replace with genuine Komatsu parts (aftermarket sensors often cause recurring codes). After replacement, perform ECM calibration through diagnostic software to ensure proper sensor baseline values. Clear codes and conduct operational testing under load to verify repair.

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Disclaimer: This guide provides general troubleshooting information. Hydraulic system diagnosis requires specialized tools and training. Always consult a certified Komatsu technician or the official service manual for your specific machine serial number before performing repairs. Improper hydraulic system work can result in serious injury or equipment damage.