What is Komatsu PC210LC-8 Fault Code E10 CA757?

Fault Code E10 CA757 indicates a communication error between the Engine Control Module (ECM) and the Hydraulic Control Module (HCM) on the Komatsu PC210LC-8 excavator. This code specifically points to a CAN bus communication failure or data transmission interruption between these two critical control systems.

The CAN (Controller Area Network) bus serves as the digital nervous system for modern excavators, allowing the ECM and HCM to share real-time operational data. When this communication link fails, the machine cannot properly coordinate engine power output with hydraulic demands. For the PC210LC-8, this is particularly critical because the integrated hydraulic system relies on constant feedback from the engine controller to optimize fuel efficiency and prevent overloading. This fault can trigger derate mode, severely limiting the machine's productivity and potentially causing unsafe operating conditions.

Common Symptoms

• Warning light illuminated on the monitor panel with "E10" or "CA757" displayed
• Reduced engine power or automatic derate to protect systems from uncoordinated operation
• Erratic hydraulic response including sluggish boom, arm, or swing functions
• Intermittent loss of throttle control or failure to respond to joystick commands
• Multiple simultaneous fault codes appearing alongside E10 CA757, indicating cascading system failures

Potential Causes

The most common technical causes for this communication fault on used PC210LC-8 excavators include:

• CAN bus wiring harness damage at known rub points near the engine-to-chassis transition and behind the operator's cab where harnesses flex during swing operations
• Corroded or loose connector pins at the ECM (located behind the battery box) or HCM (mounted near the hydraulic pump)
• Failed termination resistor on the CAN bus network (typically 120-ohm resistors at network endpoints)
• ECM or HCM internal failure, more common in high-hour machines (8,000+ hours)
• Voltage supply issues from worn alternator or weak battery causing ECM/HCM brownouts
• Water intrusion into control modules from damaged cab floor seals or failed cable glands

How to Troubleshoot and Fix Code E10 CA757

Step 1: Visual Inspection of Harnesses and Connectors

Begin by inspecting the CAN bus wiring harness between the ECM and HCM. On used excavators, focus on areas where the harness routes near sharp metal edges or moving components. Check specifically behind the battery tray and along the right-side engine compartment frame rail—these are known wear points on the PC210LC-8. Look for abraded insulation, pinched wires, or signs of rodent damage. Disconnect and inspect all connectors for green corrosion, bent pins, or moisture.

Step 2: Electrical Testing with Diagnostic Tools

Using a digital multimeter, verify CAN-High and CAN-Low voltage at both the ECM and HCM connectors (refer to Komatsu service manual for specific pin locations). With the key on and engine off, you should measure approximately 2.5V on CAN-High and 2.5V on CAN-Low (differential voltage around 0V at rest). Measure termination resistance across CAN-High and CAN-Low with all modules disconnected—you should read approximately 60 ohms (two 120-ohm resistors in parallel). Values outside 55-65 ohms indicate failed termination resistors or open circuits.

Step 3: Verify Power Supply and Ground Integrity

Check battery voltage (should be 12.5-14.5V with engine running) and test the ground connections for both control modules. Corroded grounds are extremely common on used machines. Measure voltage drop between the module ground pins and battery negative while cranking—anything over 0.3V indicates poor grounding requiring cleaning or replacement of ground straps.

Step 4: Advanced Diagnostics with Komatsu KOMTRAX or Diagnostic Software

Connect Komatsu diagnostic software (or compatible tools like Jaltest) to monitor live CAN bus traffic. This will identify whether the fault is intermittent or continuous and which module is failing to communicate. For used excavators with 5,000+ hours, perform a data snapshot during fault occurrence to determine if the issue correlates with specific operating conditions (high temperature, vibration, or electrical load).

Step 5: Component Replacement and Verification

If diagnostics point to a specific module failure, replace the ECM or HCM only after confirming harness integrity—installing new modules with damaged wiring will result in immediate failure. After any repairs, clear fault codes using diagnostic software, operate the machine through a full work cycle, and re-check for code recurrence.

Disclaimer: This guide provides general troubleshooting information. Always consult the official Komatsu service manual for your specific machine serial number and consider engaging a certified Komatsu technician for complex electrical diagnostics and repairs, especially when working with safety-critical control systems.