Komatsu PC100-6 Fault Code E315: Complete Diagnostic Guide

What is Komatsu PC100-6 Fault Code E315?

Fault Code E315 indicates a malfunction in the hydraulic pump solenoid valve circuit, specifically detecting an abnormal voltage or open/short circuit condition in the solenoid control system. This code is generated when the ECM (Engine Control Module) detects that the electrical signal to the hydraulic pump's pressure control solenoid is outside the specified range of 10-14 volts during operation.

This fault is critical for the PC100-6 because the hydraulic pump solenoid regulates system pressure and flow distribution. When this circuit fails, the excavator cannot properly modulate hydraulic power to the boom, arm, bucket, and swing functions, severely impacting productivity and potentially causing erratic machine behavior.

Common Symptoms

• Reduced hydraulic power across all functions, with noticeably slower cycle times
• Engine RPM fluctuations or hunting, especially under load
• Warning light illumination on the instrument panel (typically amber hydraulic indicator)
• Intermittent loss of specific functions, particularly bucket curl or arm crowd operations
• Machine enters derate mode, limiting maximum engine speed to approximately 1,800 RPM

Potential Causes

The most common root causes for E315 on used PC100-6 excavators include:

• Solenoid coil failure due to heat exposure and age-related insulation breakdown (resistance typically measures below 15 ohms when failed)
• Harness chafing at the pump mounting area where cables route along the engine block—a known wear point on this model
• Corroded connector pins at the 6-pin solenoid connector, particularly in machines operated in coastal or high-moisture environments
• ECM relay malfunction affecting 12V power supply to the solenoid circuit
• Broken or damaged wiring between ECM pin B23 and the solenoid connector, often from improper service access

How to Troubleshoot and Fix Code E315

Step 1: Visual Inspection Begin by inspecting the solenoid valve connector located on the main hydraulic pump (left side of engine). Check for green corrosion, bent pins, or moisture intrusion. On used machines, examine the wiring harness where it passes near the engine mount—look for insulation wear or exposed copper.

Step 2: Electrical Testing Using a digital multimeter, measure solenoid coil resistance. Disconnect the connector and test across the two solenoid terminals. Proper resistance should read 18-22 ohms at 20°C. Values below 15 ohms indicate a shorted coil; infinite resistance means an open circuit.

Step 3: Voltage Supply Check With the key on and engine off, measure voltage at the harness-side connector. You should read battery voltage (12-14V) on the power supply wire. If voltage is absent, trace back to the ECM and check fuse F7 (15A) in the main fuse panel.

Step 4: Harness Continuity Test continuity between ECM connector pin B23 and the solenoid connector. Any reading above 2 ohms suggests damaged wiring requiring repair or replacement.

For used excavators, always inspect connector seals and grommets for age-related cracking before replacing expensive components. Clean all connections with electrical contact cleaner and apply dielectric grease.

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Disclaimer: This guide provides general troubleshooting procedures. Always consult Komatsu service documentation and qualified technicians for complex repairs. Improper diagnosis can lead to additional damage or safety hazards.