Komatsu PC70-8 Fault Code DHSAMA: Complete Diagnostic Guide

What is Komatsu PC70-8 Fault Code DHSAMA?

Fault Code DHSAMA on the Komatsu PC70-8 indicates a communication error or data transmission failure within the machine's electronic control system, typically between the main controller and hydraulic system modules. This code is part of Komatsu's proprietary diagnostic system and signals that critical operational data is not being properly exchanged between control units.

The DHSAMA code specifically affects the integrated control network that manages hydraulic functions, engine performance parameters, and safety systems. When this communication breakdown occurs, the excavator's ECM (Engine Control Module) cannot properly coordinate with hydraulic controllers, potentially compromising machine efficiency and operator safety. For the PC70-8 model, this is particularly critical as it relies on precise electronic-hydraulic coordination for optimal performance.

Common Symptoms

When fault code DHSAMA is active, operators typically experience:

• Warning lights illuminated on the instrument panel, often accompanied by audible alarms
• Reduced hydraulic response or sluggish boom/arm movements due to safety derate mode
• Intermittent loss of function in specific hydraulic circuits or attachments
• Engine power limitation as the system enters protective mode to prevent damage
• Display screen errors or complete loss of monitor functionality showing operational parameters

Potential Causes

The most common technical reasons for DHSAMA code activation in used PC70-8 excavators include:

• Corroded or damaged wiring harnesses, particularly at connection points near the hydraulic pump where vibration and heat exposure are highest
• Failed CAN bus termination resistors or damaged communication cables between control modules
• Moisture intrusion into controller connectors, common in machines with compromised cab seals
• Faulty main controller or hydraulic control unit due to age-related component degradation
• Voltage irregularities from aging batteries or failing alternators affecting data transmission integrity
• Loose or oxidized ground connections at the chassis grounding points

How to Troubleshoot and Fix Code DHSAMA

Step 1: Initial Inspection Begin with a thorough visual inspection of all wiring harnesses between the main controller (located under the operator's seat) and hydraulic control modules. On used excavators, check for harness wear at known rub points near the swing bearing and along the boom base. Use a multimeter to verify battery voltage (should read 12.5-14.5V with engine running).

Step 2: Connector Examination Disconnect and inspect all controller connectors for corrosion, bent pins, or moisture. Pay special attention to the main CAN bus connectors (typically green or yellow colored). Clean contacts with electrical contact cleaner and apply dielectric grease before reconnection. Check termination resistors at both ends of the CAN bus network (should measure 60 ohms across CAN-H and CAN-L).

Step 3: Diagnostic Software Testing Connect Komatsu KOMTRAX or compatible diagnostic software to access real-time communication data. Monitor data transmission rates between modules while operating hydraulic functions. If communication drops occur during specific movements, this indicates harness damage at flex points.

Step 4: Ground Circuit Verification Verify all chassis ground connections are clean and tight. Measure resistance between controller ground pins and chassis ground (should be less than 0.5 ohms). Poor grounding is a frequent cause of communication errors in older machines.

Step 5: Component Replacement If diagnostics isolate a specific failed module, replace the controller unit or damaged harness sections. For used excavators, always replace associated connectors when installing new harnesses to prevent future corrosion issues.

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Disclaimer: This guide provides general diagnostic information. Complex electrical issues should be evaluated by certified Komatsu technicians with proper diagnostic equipment. Always consult the official service manual for your specific machine serial number before performing repairs.