Komatsu PC850SE-8R Fault Code AB00KE: Complete Diagnostic Guide

What is Komatsu PC850SE-8R Fault Code AB00KE?

Fault Code AB00KE indicates an abnormal signal or communication error in the machine's hydraulic system control circuit, specifically related to the pump flow control solenoid valve or its associated wiring harness. This code is generated when the Electronic Control Module (ECM) detects voltage irregularities, open circuits, or short circuits in the hydraulic pump control system.

In the PC850SE-8R, this fault directly impacts the machine's ability to regulate hydraulic pump output efficiently. The pump flow control system is critical for optimizing fuel consumption and matching hydraulic power to operational demands. When this code activates, the excavator may enter a protective derate mode to prevent damage to hydraulic components.

Common Symptoms

When Code AB00KE is active, operators typically experience:

• Hydraulic system warning light illuminated on the monitor panel
• Reduced swing speed and sluggish boom/arm movements due to limited pump flow
• Engine derate or power limitation, particularly under heavy load conditions
• Intermittent loss of hydraulic responsiveness during operation
• Error message displayed on the multi-function monitor indicating hydraulic system malfunction

Potential Causes

The most common technical causes for AB00KE in used PC850SE-8R excavators include:

• Damaged or corroded wiring harness connecting the ECM to the pump flow control solenoid valve (common wear point near the pump mounting area)
• Failed pump flow control solenoid valve due to internal coil breakdown or mechanical seizure
• Connector corrosion at the solenoid valve plug, especially in machines operating in wet or coastal environments
• Intermittent short circuit caused by harness chafing against the pump housing or hydraulic lines
• ECM internal fault (less common) affecting the output driver circuit for pump control
• Low voltage supply to the solenoid due to poor ground connections or battery issues

How to Troubleshoot and Fix Code AB00KE

Step 1: Visual Inspection Begin by inspecting the wiring harness routing from the ECM to the hydraulic pump area. Look for obvious damage, chafing points where the harness contacts metal surfaces, or signs of heat damage. On used excavators, pay special attention to harness protection sleeves that may have deteriorated over time.

Step 2: Connector and Resistance Testing Disconnect the solenoid valve connector and inspect for corrosion, bent pins, or moisture intrusion. Using a digital multimeter, measure the solenoid coil resistance (typically 10-30 ohms for Komatsu systems—verify with service manual specifications). Check harness continuity from the ECM connector to the solenoid plug.

Step 3: Voltage Supply Verification With the ignition on and engine running, measure voltage at the solenoid connector using Komatsu diagnostic software (KOMTRAX Plus) or a multimeter. Verify the ECM is sending proper command signals (typically 12-24V PWM signal). Check ground circuit integrity with less than 0.5 ohms resistance.

Step 4: Component Replacement If testing reveals a failed solenoid valve, replace it with a genuine Komatsu pump control solenoid. For harness damage, repair using proper gauge wire and weatherproof connectors, ensuring adequate strain relief. Clear codes using diagnostic software and perform operational testing under load.

Disclaimer: This guide provides general diagnostic information. Always consult the official Komatsu service manual for your specific serial number and consider professional assistance from certified Komatsu technicians for complex electrical diagnostics.