What is Komatsu PC210LC-8 Fault Code CA428?

Fault Code CA428 on the Komatsu PC210LC-8 indicates a communication error between the Engine Control Module (ECM) and the Hydraulic Pump Controller (HPC). This diagnostic trouble code specifically signals that the ECM is unable to receive or transmit data properly with the pump controller over the CAN (Controller Area Network) bus system.

This code is critical for the PC210LC-8 because the ECM and HPC must communicate constantly to optimize engine power output with hydraulic pump demand. When this communication link fails, the machine cannot properly match engine RPM to hydraulic flow requirements, resulting in inefficient operation and potential power loss. The CAN bus system is the digital nervous system of modern excavators, and any disruption compromises the integrated performance that makes the PC210LC-8 efficient.

Common Symptoms

When CA428 is active on your PC210LC-8, operators typically experience:

• Warning light illumination on the monitor panel, often accompanied by a specific error message about controller communication
• Reduced hydraulic response or sluggish boom/arm/bucket movements due to improper pump flow regulation
• Engine derate mode where the machine limits maximum RPM to protect systems from uncoordinated operation
• Intermittent loss of power that may come and go, especially over rough terrain or during temperature changes
• Monitor display malfunctions showing incorrect hydraulic pressure or flow readings

Potential Causes

The most common technical causes for CA428 on used PC210LC-8 excavators include:

• Corroded or damaged CAN bus wiring harness between the ECM and HPC, particularly at connector points near the pump where vibration and hydraulic fluid exposure occur
• Faulty connectors at either the ECM (located in the cab area) or HPC (mounted near the hydraulic pumps), especially connector C-103 which is prone to moisture intrusion
• Failed Hydraulic Pump Controller itself, though less common than wiring issues in used machines
• ECM software corruption or version mismatch after previous repairs or reflashing attempts
• Damaged CAN bus termination resistors (120-ohm resistors at network endpoints) due to voltage spikes or age-related degradation
• Grounding issues specific to the hydraulic pump mounting points where paint or corrosion disrupts electrical continuity

How to Troubleshoot and Fix Code CA428

Step 1: Visual Inspection of Harness and Connectors

Begin by inspecting the wiring harness running from the cab-mounted ECM to the HPC near the hydraulic pumps. On used PC210LC-8s, check for harness routing where it passes over the swing bearing and near the right-side travel motor—these are known rub points. Look for abraded insulation, crushed wires, or evidence of hydraulic oil contamination. Disconnect and inspect connectors C-103 (HPC side) and C-47 (ECM side), checking pins for corrosion, bent terminals, or moisture.

Step 2: CAN Bus Electrical Testing

Using a digital multimeter, measure the resistance between the two CAN bus wires (typically yellow and green wires in the Komatsu harness). With the key off and connectors disconnected, you should read approximately 60 ohms between CAN-High and CAN-Low, indicating proper termination resistor function. Next, check for short circuits to ground—each CAN wire should show infinite resistance to chassis ground. If readings are incorrect, inspect termination resistors and wiring for damage.

Step 3: Advanced Diagnostics with Komatsu Software

Connect Komatsu diagnostic software (KOMTRAX Plus or an equivalent diagnostic tool) to the machine's diagnostic port. Monitor live CAN bus traffic while attempting communication with the HPC. The software will show whether messages are being sent but not acknowledged, which points to controller failure, or if no messages appear, indicating complete wiring failure. Check for additional stored codes that might indicate the failure sequence.

Step 4: Component Testing and Replacement

If wiring and connections test good, test the HPC power supply (should be battery voltage when key is on) and ground circuit (less than 0.5 ohms to chassis). For used excavators, remove the HPC and inspect its mounting area for corrosion that could create grounding problems. If all electrical tests pass, the controller itself may need replacement—ensure any replacement HPC is programmed with the correct software version matching your ECM's calibration.

Critical for Used Equipment: Before replacing expensive controllers, always address wear-related issues first. On machines with over 5,000 hours, harness flexing and connector corrosion account for approximately 70% of communication codes.

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