What is Komatsu PC200LC-7 Fault Code E115?

Fault Code E115 on the Komatsu PC200LC-7 indicates a malfunction in the Engine Controller (ECM) communication circuit, specifically a timeout or loss of communication between the main controller and the engine control unit. This code triggers when the machine's monitoring system detects that critical data exchange between controllers has been interrupted or is taking longer than the programmed threshold allows.

The PC200LC-7 relies on continuous CAN (Controller Area Network) communication between its engine ECM and the machine controller to coordinate hydraulic functions, monitor engine parameters, and ensure optimal performance. When this communication fails, the excavator's integrated systems cannot properly synchronize, which can lead to reduced operational capability or complete shutdown to prevent potential damage. For used excavators, this fault often emerges due to age-related electrical degradation rather than catastrophic component failure.

Common Symptoms

• Warning light illumination on the instrument cluster, typically the engine or system malfunction indicator
• Reduced engine power (derate mode) where the machine operates at limited RPM to protect systems
• Intermittent loss of monitor panel functions, including blank displays or frozen gauge readings
• Erratic hydraulic response or delayed actuation of boom, bucket, or swing functions
• Engine starting difficulties or unexpected shutdowns during operation, particularly under load

Potential Causes

The most frequent causes of Code E115 on used Komatsu PC200LC-7 excavators include:

• Corroded or loose connectors at the ECM harness connection points, especially the 38-pin main connector which is prone to moisture intrusion in older machines
• Damaged CAN bus wiring between the engine ECM and machine controller, particularly where harnesses route near the engine mount or through the turntable passage (known rub points on this model)
• Failing engine ECM due to internal circuit board degradation, capacitor failure, or voltage spike damage common in high-hour used machines
• Poor ground connections at chassis grounding points G101 or G103, which deteriorate due to corrosion on aged equipment
• Voltage supply issues from the main power relay or battery connections providing inconsistent power to the ECM

How to Troubleshoot and Fix Code E115

Step 1: Visual Inspection and Connection Check Begin by inspecting all ECM connectors for corrosion, bent pins, or moisture. Disconnect the main 38-pin ECM connector and examine both the harness side and ECM side for green corrosion (common on used machines). Clean contacts with electrical contact cleaner and apply dielectric grease before reconnecting. Check that connector lock tabs are secure.

Step 2: Test Communication Circuit Integrity Using a digital multimeter, check for continuity on the CAN-High and CAN-Low wires (typically yellow and green wires in the harness). With ignition off, measure resistance between CAN terminals at the ECM connector—you should read approximately 60 ohms across the bus termination. Inspect harness routing near the swing circle and engine mounts for chafing or damage, as these are known wear points on the PC200LC-7.

Step 3: Voltage and Ground Verification With ignition on, verify the ECM receives stable 24V power at the supply pin (consult your service manual for specific pin locations). Check ground connections by measuring voltage drop between the ECM ground pin and battery negative—it should be less than 0.1V. For used excavators, remove ground connection bolts at chassis points, wire-brush contact surfaces to bare metal, and reinstall with star washers.

Step 4: Advanced Diagnostics with Komatsu Software If basic checks don't resolve the issue, connect Komatsu diagnostic software (KTMS or equivalent) to monitor real-time communication data. This will show specific communication dropout patterns that can pinpoint intermittent failures. On high-hour used machines, ECM replacement may be necessary if internal failures are confirmed, though verifying all wiring first prevents unnecessary parts replacement.

Disclaimer: This guide provides general troubleshooting information. Always consult the official Komatsu service manual for your specific machine serial number and consider professional diagnostic assistance for complex electrical issues.