What is Komatsu PC220-10 Fault Code CA325?

Fault Code CA325 on the Komatsu PC220-10 excavator indicates a communication error between the engine controller (ECM) and the hydraulic system controller (ECOM/CLSS), specifically related to the pump control system data transmission failure. This code is part of Komatsu's advanced Controller Area Network (CAN) bus communication protocol that coordinates engine power output with hydraulic pump demand.

The PC220-10 uses a sophisticated closed-center load-sensing (CLSS) hydraulic system that requires constant communication between the engine and hydraulic controllers to optimize fuel efficiency and performance. When the ECM cannot receive proper pump load signals from the hydraulic controller, it triggers CA325 and may force the machine into a protective derate mode. This disruption prevents the system from matching engine speed to hydraulic load demand, which is critical for maintaining the PC220-10's fuel-efficient operation and preventing component damage from improper loading conditions.

Common Symptoms

• Yellow warning light illuminated on the instrument cluster with reduced machine responsiveness
• Loss of power matching between engine RPM and hydraulic functions, causing sluggish operation
• Intermittent loss of hydraulic power during combined functions (boom and swing simultaneously)
• Engine running at fixed RPM regardless of joystick input or load changes
• Fault code stored in memory even after machine appears to operate normally

Potential Causes

The most common technical causes for CA325 on used PC220-10 excavators include:

• CAN bus harness damage at known wear points near the engine mounting bracket and along the right-side frame rail where cable routing creates friction against metal edges
• Corroded or moisture-contaminated connectors at the C102 connector junction box located behind the cab, particularly on machines operating in high-humidity environments
• Failed ECOM controller module due to vibration damage or capacitor degradation (common after 8,000+ operating hours)
• Low voltage supply to controllers caused by deteriorating main harness grounds at G201 (engine block ground point)
• Damaged termination resistor on the CAN bus network (120-ohm resistor failure)
• ECM software version mismatch after controller replacement without proper programming synchronization

How to Troubleshoot and Fix Code CA325

Step 1: Initial Visual Inspection and Data Capture

Connect Komatsu KOMTRAX Plus diagnostic software or a compatible CAN bus scanner to retrieve all active and inactive codes. Check freeze-frame data to identify when communication loss occurs (idle vs. operation). Physically inspect the CAN-H and CAN-L wiring (typically yellow and green twisted-pair wires) along the engine-to-cab harness route. On used excavators, look specifically for harness abrasion near the right-side pivot point and at the engine firewall penetration where rubber grommets may have deteriorated.

Step 2: Electrical Testing of CAN Bus Network

Using a digital multimeter, measure CAN bus resistance between CAN-H and CAN-L terminals with ignition off and all controllers connected—you should read approximately 60 ohms (two 120-ohm terminating resistors in parallel). Readings above 100 ohms or below 40 ohms indicate termination resistor failure or harness short circuits. Test voltage levels with ignition on: CAN-H should measure approximately 2.5-3.5V, and CAN-L around 1.5-2.5V at rest. Check for proper grounding at G201 engine ground—clean and tighten if resistance exceeds 0.5 ohms.

Step 3: Controller and Connector Testing

Disconnect the C102 connector behind the operator's cab and inspect for green corrosion, bent pins, or moisture intrusion—extremely common on used machines. Clean with electrical contact cleaner and apply dielectric grease before reconnection. If harness and connections test properly, perform a controller substitution test starting with the ECOM hydraulic controller, as this component experiences more vibration stress than the ECM. For used excavators with 6,000+ hours, consider testing the alternator output under load (should maintain 27-29V on this 24V system) as voltage fluctuations can cause intermittent communication errors that manifest as CA325.

Professional Disclaimer: While these troubleshooting steps address the most common CA325 causes, complex CAN bus communication issues may require factory-level diagnostic equipment and software calibration. Always consult Komatsu technical support or a certified technician when controller replacement or reprogramming is necessary, as improper ECM/ECOM synchronization can create additional fault codes.