What is Komatsu PC1250-11R Fault Code DHSAMA?

Fault Code DHSAMA on the Komatsu PC1250-11R indicates a communication error or data mismatch between the main controller (VCMS - Vehicle Control Management System) and the hydraulic system's proportional pressure control solenoid valve circuit. This code specifically points to an abnormal signal detected in the hydraulic system's electronic control network, affecting the machine's ability to properly regulate hydraulic pressure for optimal attachment and swing function performance.

This fault is critical for the PC1250-11R because this mining-class excavator relies on precise hydraulic pressure modulation to manage its massive bucket forces and swing torque. When the VCMS cannot properly communicate with the proportional solenoid valves, the machine may enter a protective derate mode to prevent damage to hydraulic components or erratic machine behavior that could compromise jobsite safety.

Common Symptoms

• Hydraulic system warning lamp illuminated on the main monitor display with fault code stored in memory
• Reduced hydraulic response or sluggish operation in boom, arm, or swing functions
• Intermittent loss of fine control during precision digging or grading operations
• Machine may enter limited performance mode, restricting maximum hydraulic flow or pressure
• Erratic attachment speed or inconsistent breakout force during bucket loading cycles

Potential Causes

The DHSAMA code in used PC1250-11R excavators typically stems from several age-related failures:

• Corroded or damaged wiring harness connectors at the proportional solenoid valve assembly, particularly where harnesses route near the swing bearing
• Failed proportional pressure control solenoid valve due to contaminated hydraulic oil causing internal coil or spool damage
• ECU/VCMS internal communication fault from voltage irregularities or ground connection degradation
• Damaged CAN bus wiring between controllers, common at flex points near the cab mounting or counterweight
• Hydraulic oil contamination causing solenoid valve sticking and inconsistent electrical feedback signals
• Loose or corroded ground connections at the main controller mounting brackets

How to Troubleshoot and Fix Code DHSAMA

Step 1: Connect Komatsu Diagnostic Software Use KOMTRAX Plus or compatible Komatsu diagnostic software to read live data from the VCMS. Check for additional active or pending codes that may indicate related electrical issues. Record freeze frame data showing operating conditions when the fault occurred.

Step 2: Inspect Proportional Solenoid Valve Harness Physically inspect the wiring harness leading to the hydraulic pump's proportional pressure control solenoid valves. On used PC1250-11R machines, check for harness wear at the swing bearing passage and near hydraulic line routing points. Look for chafed insulation, corroded pins, or moisture intrusion in connectors.

Step 3: Test Solenoid Valve Electrical Values Disconnect the solenoid valve connector and measure coil resistance using a quality digital multimeter. Typical resistance should be 3-8 ohms (verify with Komatsu specifications). Check for voltage supply at the harness side—should read approximately 12-24V DC with key on. Any readings outside specifications indicate wiring faults or ECU output problems.

Step 4: Verify Ground Connections Inspect all ground terminals at the VCMS mounting location and hydraulic valve body. Clean contact surfaces and apply dielectric grease to prevent future corrosion. Poor grounds are extremely common in used excavators operating in mining environments.

Step 5: Check Hydraulic Oil Condition Sample and analyze hydraulic oil for contamination. Metal particles or water content can cause solenoid valves to stick, creating erratic electrical feedback that triggers DHSAMA codes. Replace filters and flush system if contamination is detected.

Disclaimer: This guide provides general troubleshooting information. Always consult Komatsu service manuals and qualified technicians for machine-specific procedures. Improper diagnostics on high-voltage systems can cause injury or equipment damage.