Komatsu PC210LC-8 Fault Code CA155: Complete Diagnostic Guide

What is Komatsu PC210LC-8 Fault Code CA155?

Fault Code CA155 indicates a communication error between the Engine Controller (ECM) and the Machine Controller in the Komatsu PC210LC-8 excavator. This code specifically identifies a CAN bus communication failure on the machine's integrated network system, which coordinates data exchange between the engine management system and the hydraulic control systems.

This fault is critical because the PC210LC-8 relies on constant communication between controllers to optimize fuel efficiency, hydraulic performance, and emissions control. When this communication breaks down, the machine cannot properly coordinate engine output with hydraulic demand, potentially triggering derate modes or complete operational shutdown to prevent component damage.

Common Symptoms

When CA155 is active on your Komatsu PC210LC-8, you may experience:

• Warning light illuminated on the instrument cluster with reduced engine power
• Machine enters limited operation mode with restricted hydraulic functions
• Intermittent loss of monitor display data (fuel consumption, operating hours)
• Engine rpm limiting to approximately 1,500 rpm regardless of throttle input
• Erratic hydraulic response or uncoordinated multi-function operation

Potential Causes

Several factors commonly trigger CA155 in used PC210LC-8 excavators:

• CAN bus wiring harness damage from rubbing against frame components near the engine firewall (known wear point on this model)
• Corroded or loose connector terminals at the ECM or machine controller, especially in machines operating in wet/coastal environments
• Failed 120-ohm terminating resistor on the CAN network
• ECM or machine controller internal failure (less common but possible in high-hour units)
• Water intrusion into harness connectors located under the operator platform
• Previous repair attempts using non-OEM wiring causing impedance mismatches

How to Troubleshoot and Fix Code CA155

Step 1: Visual Inspection Inspect the main wiring harness running from the engine compartment to the cab. On used PC210LC-8s, check for harness abrasion where it passes through the bulkhead grommet. Look for green corrosion on CAN-H and CAN-L wire terminals (typically orange and yellow wires).

Step 2: Connector Testing Disconnect the ECM connector (20-pin) and machine controller connector. Using contact cleaner, clean all pins. Check for bent pins or moisture. Measure resistance between CAN-H and CAN-L lines—should read approximately 60 ohms with controllers disconnected (indicating proper terminating resistors).

Step 3: Voltage and Signal Testing With ignition on, engine off, use a multimeter to verify CAN bus voltage at the ECM connector: CAN-H should read 2.5-3.5V, CAN-L should read 1.5-2.5V. Use Komatsu's KOMTRAX diagnostic software to monitor real-time communication packets and identify which controller is failing to respond.

Step 4: Harness Continuity Check For used excavators, perform a wiggle test while monitoring live data—flex the harness at known friction points while observing for communication drops. Replace any sections showing intermittent readings.

Step 5: Component Replacement If all wiring tests pass, the failure is likely internal. Replace the machine controller first (more common failure point), then ECM if issues persist.

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Disclaimer: This guide provides general troubleshooting information. Always consult the official Komatsu service manual for your specific machine serial number and consider professional diagnostics for complex electrical issues. Improper repairs can cause additional system damage.