Komatsu PC850SE-8R Fault Code E10CA757: Technical Guide

What is Komatsu PC850SE-8R Fault Code E10CA757?

Fault Code E10CA757 indicates a communication error or data transmission failure within the machine's CAN (Controller Area Network) bus system, specifically related to the engine controller (ECM) and hydraulic system controller communication pathway.

This diagnostic trouble code (DTC) signals that the Engine Control Module (ECM) is not receiving proper data signals from one or more controllers on the network, or there's an interruption in the CAN bus communication line. For the PC850SE-8R, this is critical because the integrated control system relies on constant data exchange between the engine management system and hydraulic controllers to optimize performance, fuel efficiency, and emissions control. When this communication breaks down, the machine cannot properly coordinate engine output with hydraulic demand, potentially causing operational inefficiencies or complete system shutdowns.

Common Symptoms

When Code E10CA757 is active, operators typically experience:

• Warning lights illuminated on the monitor panel, specifically communication error indicators or check engine lights
• Reduced engine power or derate mode activation, limiting machine performance to protect components
• Erratic hydraulic response or delayed actuator movements due to loss of coordinated control
• Intermittent system shutdowns or failure to start, particularly after the machine has warmed up
• Multiple fault codes appearing simultaneously as various controllers lose communication

Potential Causes

The most likely technical reasons for E10CA757 on used PC850SE-8R excavators include:

• CAN bus wiring harness damage from rubbing against frame components, particularly near the engine bay and swing bearing area where harnesses experience repeated flexing
• Corroded or loose connector pins at the ECM, hydraulic controller, or junction box connections due to moisture intrusion
• Failed termination resistors on the CAN network causing signal reflection and data corruption
• ECM or controller module failure, more common in high-hour machines with exposure to extreme temperatures
• Voltage supply issues to controllers from failing alternators or damaged power distribution circuits
• Aftermarket component interference from non-OEM parts disrupting network protocols

How to Troubleshoot and Fix Code E10CA757

Step 1: Initial Diagnostic Scan Connect Komatsu KOMTRAX diagnostic software or a compatible scan tool to retrieve all active and pending codes. Document freeze frame data to identify which specific controller lost communication. Check battery voltage—ensure it maintains 24-26V during cranking, as low voltage can cause false communication errors.

Step 2: Physical Harness Inspection Perform a thorough visual inspection of the CAN bus harness routing from the ECM (located behind the operator cab) to all network controllers. On used excavators, pay special attention to harness sections near the swing bearing, engine mounts, and hydraulic pump area where vibration and movement cause wear. Look for abraded insulation, pinched wires, or evidence of previous repairs with improper splicing.

Step 3: Connector and Resistance Testing Disconnect and inspect all CAN High and CAN Low wire connectors. Clean pins with electrical contact cleaner and check for bent or corroded terminals. Using a digital multimeter, measure resistance between CAN High and CAN Low lines with all controllers disconnected—you should read approximately 60 ohms if termination resistors are functioning correctly. Measure continuity of each CAN wire individually to verify no opens or shorts to ground.

Step 4: Controller Power Supply Verification Verify each controller receives proper supply voltage (typically 24V) and clean ground connections. Check voltage drop across ground circuits—anything above 0.2V indicates resistance from corrosion or loose connections, common in older machines.

Step 5: Component Replacement and Verification If physical inspection and electrical testing reveal damaged harnesses or connectors, repair using OEM-spec shielded twisted-pair wire and heat-shrink solder connections. Replace any controllers only after confirming wiring integrity. After repairs, clear codes, operate the machine through full work cycles, and rescan to verify the fault doesn't return.

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Disclaimer: This guide provides general troubleshooting information for experienced technicians. Always consult the official Komatsu service manual for your specific serial number and consider professional diagnostic services for complex electrical issues. Improper repairs to CAN bus systems can cause additional controller damage.