What is Komatsu PC210LC-10 Fault Code 989N00?

Fault Code 989N00 on the Komatsu PC210LC-10 indicates a communication error between the machine's Engine Controller (ECM) and the Pump Controller (PMC). This diagnostic trouble code signals that the Controllers Area Network (CAN) communication line has detected an abnormal signal or complete loss of data exchange between these critical control modules.

This code is particularly serious for the PC210LC-10 because the ECM and PMC must constantly communicate to optimize engine performance with hydraulic pump output. When this communication fails, the machine cannot properly match engine speed with hydraulic demand, resulting in poor fuel efficiency, reduced digging force, and potential safety concerns. The PC210LC-10's advanced hydraulic management system relies on this constant data exchange to deliver the precise control operators expect from this 21-ton class excavator.

Common Symptoms

• Dashboard warning lamp illuminated (typically the engine or hydraulic system icon) with reduced machine responsiveness
• Noticeable loss of hydraulic power during digging or lifting operations, even at full throttle
• Engine may enter derate mode, limiting RPMs to 1,500 or lower to protect components
• Erratic or sluggish swing function and inconsistent boom/arm speed
• Machine may intermittently return to normal operation, then suddenly lose power again (indicating an intermittent connection issue)

Potential Causes

The most common technical causes for Code 989N00 on used PC210LC-10 excavators include:

• CAN bus wiring harness damage – particularly at stress points near the engine mounting brackets or behind the cab where harnesses flex during swing operation
• Corroded or moisture-contaminated connector pins on the ECM or PMC modules (common on machines operating in wet or coastal environments)
• Failed or failing ECM or PMC controller due to age, vibration damage, or previous electrical surges
• Voltage supply issues to either controller from the main electrical harness or battery connections
• Physical damage to the CAN communication lines (twisted-pair orange/brown wires) from rodent damage or improper previous repairs

How to Troubleshoot and Fix Code 989N00

Step 1: Visual Inspection of Harness and Connectors Begin by thoroughly inspecting all wiring between the ECM (located near the engine) and PMC (typically mounted on the main pump). On used excavators, check specifically where harnesses pass through the swing bearing area and along the engine mounts—these are known rub points. Look for chafed insulation, crushed wires, or connector corrosion. Clean all connector pins with electrical contact cleaner and apply dielectric grease.

Step 2: Verify CAN Bus Communication Lines Using a digital multimeter, check the CAN-High and CAN-Low lines (orange and brown wires). With the key on but engine off, you should measure approximately 2.5V on CAN-High and 2.5V on CAN-Low at rest. The resistance between these two lines should read 60 ohms with controllers disconnected, indicating proper termination resistors. Any significant deviation suggests a short, open circuit, or termination resistor failure.

Step 3: Test Individual Controller Function Connect Komatsu KOMTRAX diagnostic software or a compatible CAN diagnostic tool to isolate which controller isn't responding. Clear the code and observe if it returns immediately or only during operation. If the code reappears instantly, suspect a controller failure. For used machines over 8,000 hours, ECM capacitor aging is common—controllers may need refurbishment or replacement.

Step 4: Check Power Supply and Grounds Verify that both controllers receive proper battery voltage (12-14V) and have clean, tight ground connections. Corroded ground straps are especially common on older PC210LC machines. Check ground resistance—it should be less than 0.5 ohms to the chassis.

Professional Disclaimer: This guide provides general troubleshooting direction for experienced technicians. Always consult the official Komatsu service manual for your specific machine serial number, and consider engaging a certified Komatsu technician for controller replacement or complex electrical diagnostics, as improper repairs may cause additional damage to expensive electronic components.