What is Komatsu PC210LC-10 Fault Code CA187?

Fault Code CA187 on the Komatsu PC210LC-10 indicates an abnormality in the engine control system's communication circuit, specifically a CAN (Controller Area Network) communication error between the engine ECM (Engine Control Module) and the machine monitor. This fault typically means the ECM is not receiving or transmitting data properly through the CAN bus network, which is the digital nervous system connecting all electronic controllers on the excavator.

This code is critical for the PC210LC-10 because modern Komatsu excavators rely on continuous data exchange between the engine controller, hydraulic controller, and monitor panel to optimize fuel efficiency, emissions control, and performance. When CAN communication fails, the machine cannot properly coordinate these systems, potentially leading to reduced power output or safety shutdowns to protect the engine and hydraulics.

Common Symptoms

When CA187 is active on your PC210LC-10, operators typically experience:

• Warning light illumination on the instrument cluster, often accompanied by audible alerts
• Intermittent or complete loss of gauge readings (engine RPM, coolant temperature, fuel level may display incorrectly or not at all)
• Engine power derate or restricted operation mode where the excavator enters a "limp mode" with reduced hydraulic performance
• Inability to access diagnostic information through the monitor panel
• Erratic engine behavior including unexpected idle speed fluctuations or difficulty starting

Potential Causes

For used PC210LC-10 excavators, the most common technical causes include:

• Corroded or damaged CAN bus connectors between the ECM and monitor (particularly at the main harness connection behind the cab)
• Frayed or pinched wiring along harness routing points near the engine bay or cab pivot area where cables flex during operation
• Failed termination resistor in the CAN network circuit (a known wear item on older Komatsu machines)
• ECM or monitor controller failure due to voltage spikes, water intrusion, or age-related component degradation
• Poor ground connections at ECM mounting points, which become corroded in high-humidity operating environments
• Aftermarket radio or accessory installation that interfered with CAN bus wiring

How to Troubleshoot and Fix Code CA187

Step 1: Visual Inspection of Harnesses and Connectors Begin by inspecting all CAN bus harness connections between the engine ECM (located on the right side of the engine) and the cab monitor. Look for obvious damage, corrosion (green or white deposits), or connector pins pushed back in their housings. On used excavators, pay special attention to harness routing where cables contact metal surfaces or moving components—this is where insulation typically wears through.

Step 2: Test CAN Bus Voltage and Resistance Using a digital multimeter, check the CAN-High and CAN-Low voltage at the ECM connector. With the key on and engine off, you should read approximately 2.5V on CAN-High and 2.5V on CAN-Low (idle state). Next, measure resistance between CAN-High and CAN-Low terminals; proper termination resistance should read approximately 60 ohms. Readings significantly outside this range indicate failed termination resistors or short circuits.

Step 3: Check Ground Circuits and Power Supply Verify that the ECM has a solid ground connection by measuring voltage drop between the ECM ground pin and battery negative (should be less than 0.1V with engine running). Check that the ECM receives proper supply voltage (approximately 24V on this model). Corroded ground points are extremely common on used machines and often cause intermittent communication faults.

Step 4: Use Komatsu Diagnostic Software Connect Komatsu KOMTRAX or PC-based diagnostic software to access detailed fault information. This will show which specific controller is dropping communication and whether the fault is intermittent or constant. For used excavators without service history, this step reveals whether previous technicians attempted repairs that may have created new problems.

Step 5: Replace Faulty Components If diagnostics point to a specific failed component, replace the CAN termination resistor (located in the main junction box), damaged harness sections, or faulty controllers. Before replacing the expensive ECM or monitor, always verify the wiring and connections are perfect—approximately 70% of CA187 faults on used excavators are harness-related, not controller failures.

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Disclaimer: This guide provides general troubleshooting information for CA187 on Komatsu PC210LC-10 excavators. Always consult the manufacturer's service manual and consider professional diagnostic assistance for complex electrical issues. Improper repairs can cause additional damage to electronic systems.