Komatsu PC200-10 Fault Code DHSAMA: Complete Diagnostic Guide

What is Komatsu PC200-10 Fault Code DHSAMA?

Fault Code DHSAMA indicates a Hydraulic System Abnormal Main Pump Angle sensor malfunction on the Komatsu PC200-10 excavator. This diagnostic trouble code (DTC) signals that the Electronic Control Module (ECM) has detected inconsistent or out-of-range voltage signals from the main hydraulic pump swash plate angle sensor.

This sensor is critical for the PC200-10's advanced CLSS (Closed-Center Load Sensing System), which monitors pump displacement angle to optimize hydraulic flow and fuel efficiency. When the ECM cannot accurately read pump angle positioning, it affects the machine's ability to match hydraulic output to operational demand, potentially causing performance loss and increased fuel consumption.

Common Symptoms

When fault code DHSAMA is active, operators typically experience:

• Hydraulic system derate or reduced pump output, resulting in slow cycle times and weak digging/lifting force
• Monitor panel warning displaying the DHSAMA code with amber or red caution lights
• Erratic hydraulic response where attachment speed varies unexpectedly under consistent joystick input
• Increased engine RPM without corresponding increases in work output due to pump control mismatch
• Intermittent fault activation especially during temperature changes or after machine warm-up on used equipment

Potential Causes

The most common technical causes for DHSAMA on used PC200-10 excavators include:

• Angle sensor internal failure due to age-related wear, contamination, or thermal cycling damage
• Wiring harness damage at known rub points near the main pump mounting bracket where vibration causes insulation breakdown
• Connector corrosion on the 4-pin sensor connector, especially on machines operating in high-moisture or marine environments
• ECM power supply issues providing inconsistent reference voltage (typically 5V) to the angle sensor circuit
• Mechanical pump problems where the swash plate position doesn't match sensor output due to worn servo pistons or control valves

How to Troubleshoot and Fix Code DHSAMA

Step 1: Connect Diagnostic Software Use Komatsu KOMTRAX Plus or compatible diagnostic software to capture live sensor data. Monitor the angle sensor voltage output (normal range: 0.5-4.5V) while observing pump angle changes during engine idle and load conditions.

Step 2: Inspect Sensor and Harness Locate the main pump angle sensor on the pump's servo control assembly. For used excavators, carefully inspect the wiring harness for abrasion points where it contacts the pump housing or frame rails—this is a common failure point after 5,000+ operating hours. Check the sensor connector for corrosion, moisture intrusion, or bent pins.

Step 3: Perform Electrical Testing Using a digital multimeter, verify the ECM reference voltage at the sensor connector (should read 4.8-5.2V with key on, engine off). Check sensor ground continuity (less than 1 ohm resistance to chassis ground). Measure sensor output voltage while manually moving the pump angle control—voltage should change smoothly without dropouts.

Step 4: Component Replacement If testing reveals sensor failure, replace with genuine Komatsu parts (part number specific to PC200-10 serial number range). On used machines, always replace the connector pigtail simultaneously, as internal connector corrosion often contributes to intermittent faults. After replacement, calibrate the sensor using diagnostic software calibration procedures.

Disclaimer: This guide provides general diagnostic information. Always consult the official Komatsu PC200-10 service manual and consider professional technician assistance for complex hydraulic system repairs. Improper diagnosis may cause additional damage or safety hazards.