What is Komatsu PC200LC-7 Fault Code E-27?

Fault Code E-27 on the Komatsu PC200LC-7 indicates a malfunction in the pump control solenoid circuit within the hydraulic system. This code is triggered when the Engine Control Module (ECM) detects an abnormal voltage or current flow in the solenoid that regulates hydraulic pump displacement, directly affecting the machine's hydraulic output and fuel efficiency.

The pump control solenoid is critical to the PC200LC-7's performance because it modulates hydraulic flow based on load demand. When this solenoid circuit fails, the excavator cannot properly adjust pump output, leading to reduced operational efficiency and potential engine overload. This is particularly important in the PC200LC-7's variable displacement pump system, which is designed to match hydraulic power to work requirements while minimizing fuel consumption.

Common Symptoms

When Code E-27 is active, operators typically experience:

• Slow or sluggish hydraulic response across all functions (boom, arm, bucket, and swing)
• Intermittent loss of hydraulic power during operation, especially under heavy loads
• Warning light illumination on the monitor panel with accompanying error code display
• Increased engine RPM without corresponding increase in hydraulic performance
• Inconsistent hydraulic pressure causing jerky or erratic movements

Potential Causes

The most common technical reasons for Code E-27 on used PC200LC-7 excavators include:

• Worn or damaged pump control solenoid due to extended operating hours and internal coil degradation
• Corroded or loose electrical connectors at the solenoid harness connection point near the hydraulic pump
• Frayed wiring harness where the cable rubs against the pump housing or frame—a known wear point on this model
• Failed ECM relay or internal ECM circuit board damage affecting solenoid driver output
• Contaminated hydraulic oil causing solenoid valve sticking or reduced electrical conductivity through grounding issues
• Voltage drop in the machine's electrical system due to aging battery cables or poor chassis ground connections

How to Troubleshoot and Fix Code E-27

Step 1: Visual Inspection Begin by inspecting the pump control solenoid wiring harness running from the ECM to the hydraulic pump. On used excavators, check specifically where the harness passes near the pump mounting bracket—this is a common rub point. Look for abraded insulation, corroded connectors, or oil contamination on electrical connections.

Step 2: Electrical Testing Using a digital multimeter, perform resistance and voltage checks. Disconnect the solenoid connector and measure coil resistance (typically 3-7 ohms for this model). Then check for supply voltage at the harness connector with the ignition on (should read approximately 12-24V depending on system state). Test continuity from the solenoid ground terminal to chassis ground.

Step 3: Solenoid Function Test If electrical values are within specification, use Komatsu diagnostic software (KOMTRAX or PC service tool) to command the solenoid while monitoring current draw. Abnormal current (too high or too low) indicates internal solenoid failure. For used machines, remove and physically inspect the solenoid valve for contamination or mechanical binding.

Step 4: ECM and Relay Verification Check the pump control relay in the fuse/relay box. Swap with an identical relay to rule out failure. If the problem persists, the ECM solenoid driver circuit may be faulty—this requires professional ECM testing or replacement.

Step 5: Post-Repair Validation After repairs, clear codes using diagnostic software, operate the machine through full hydraulic cycles, and monitor for code recurrence. Check hydraulic oil quality and replace filters if contamination was a contributing factor.

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Disclaimer: This guide provides general troubleshooting information for Komatsu PC200LC-7 excavators. Hydraulic and electrical systems involve high pressures and voltages. Always consult the official Komatsu service manual and consider professional diagnostic services, especially for used machines with unknown maintenance history.