What is Komatsu PC200LC-8 Fault Code E10 CA757?

Fault Code E10 CA757 indicates a communication error between the main Engine Control Module (ECM) and the hydraulic pump controller (CLSS - Closed Center Load Sensing System) on the Komatsu PC200LC-8 excavator. This diagnostic trouble code specifically signals that the ECM has detected an abnormal or interrupted CAN bus communication signal from the hydraulic system's electronic control unit.

This code is critical for the PC200LC-8's performance because the CLSS controller continuously communicates pump flow and pressure data to optimize fuel efficiency and hydraulic response. When this communication link fails, the machine cannot properly coordinate engine output with hydraulic demand, resulting in reduced operational efficiency and potential power limitations.

Common Symptoms

When fault code E10 CA757 is active, operators typically experience:

• Warning light illumination on the monitor panel, often accompanied by a specific error message regarding hydraulic system communication
• Reduced hydraulic response or sluggish boom/arm/bucket movements, particularly under heavy loads
• Engine derate mode where maximum RPM is limited to protect the drivetrain from uncoordinated operation
• Intermittent loss of fine control during precision digging or grading operations
• Increased fuel consumption as the engine cannot optimize output based on hydraulic load feedback

Potential Causes

The most common technical causes for E10 CA757 on used PC200LC-8 excavators include:

• CAN bus wiring harness damage between the ECM and hydraulic pump controller, especially at known rub points near the engine mount brackets and along the main boom pivot area
• Corroded or loose connector pins at the CLSS controller (typically located near the hydraulic pump assembly) due to moisture intrusion over years of operation
• Failed hydraulic pump controller module itself, which becomes more common after 8,000+ operating hours
• ECM internal communication circuit failure, though less common than harness issues
• Low system voltage (below 22V on this 24V system) causing intermittent communication dropouts during high electrical load conditions

How to Troubleshoot and Fix Code E10 CA757

Step 1: Visual Inspection and Connector Check Begin by inspecting the wiring harness running from the engine bay ECM to the hydraulic pump area. On used excavators, check for harness wear at the engine mounting brackets and where cables route past moving components. Remove and inspect both the ECM connector and CLSS controller connector for corrosion, bent pins, or moisture. Clean contacts with electrical contact cleaner and apply dielectric grease.

Step 2: CAN Bus Continuity and Resistance Testing Using a digital multimeter, check continuity on the CAN-High and CAN-Low wires between the ECM and pump controller (typically pins identified in the service manual as CAN-H and CAN-L). Measure termination resistance across the CAN bus—it should read approximately 60 ohms with both controllers connected. Significantly higher readings indicate an open circuit or poor connection.

Step 3: Voltage Supply Verification With the ignition on, verify that the CLSS controller is receiving proper supply voltage (should be 22-26V). Check ground integrity at both the controller mounting point and the ECM. Poor grounding is extremely common on used machines due to paint buildup or corrosion at mounting surfaces.

Step 4: Advanced Diagnostics with Komatsu Software Connect Komatsu KOMTRAX or PC-compatible diagnostic software to monitor real-time CAN bus communication. This will show whether messages are being transmitted but corrupted, or if communication is completely absent. If the software shows intermittent communication, focus on harness flexing points and connector integrity rather than replacing controllers.

Step 5: Component Replacement Priority If all wiring and connections test good, replace components in this order: CLSS controller first (more failure-prone), then ECM if necessary. For used excavators, always source OEM Komatsu parts or verified remanufactured units, as aftermarket controllers often have incompatible firmware versions.

---

Disclaimer: This guide provides general troubleshooting information for the Komatsu PC200LC-8. Always consult the manufacturer's service manual for model-specific procedures, torque specifications, and safety precautions. If you're unfamiliar with electrical diagnostics or CAN bus systems, consult a certified Komatsu technician to prevent further damage to electronic components.