Komatsu PC750LC-7 Fault Code E315: Complete Diagnostic Guide

What is Komatsu PC750LC-7 Fault Code E315?

Fault Code E315 indicates a malfunction in the hydraulic pump control system, specifically related to the pump flow control solenoid valve circuit. This code is triggered when the Electronic Control Module (ECM) detects an abnormal voltage or current reading from the pump control solenoid, which regulates hydraulic flow based on operational demands.

In the PC750LC-7, this system is critical for maintaining optimal hydraulic performance and fuel efficiency. The pump flow control solenoid modulates hydraulic output to match load requirements, and any disruption can significantly impact machine productivity and increase fuel consumption. This fault directly affects the excavator's ability to deliver precise hydraulic power to attachments and travel functions.

Common Symptoms

When Code E315 is active, operators typically experience:

• Reduced hydraulic power across all functions, with noticeably slower cycle times
• Warning light illumination on the monitor panel with fault code display
• Erratic hydraulic response or inconsistent flow during combined operations
• Increased engine RPM without corresponding hydraulic output (pump compensation failure)
• Potential derate mode where machine limits maximum performance to prevent damage

Potential Causes

The most common technical causes for E315 on used PC750LC-7 excavators include:

• Solenoid valve coil failure due to age-related deterioration or overheating
• Wiring harness damage at known rub points near the pump assembly or main frame pivot
• Corroded or loose connector pins at the solenoid valve connection (common in high-hour machines)
• ECM internal circuit degradation affecting solenoid driver output
• Hydraulic contamination causing mechanical binding of the solenoid spool
• Voltage supply issues from damaged power distribution harnesses

How to Troubleshoot and Fix Code E315

Step 1: Visual Inspection Begin by inspecting the pump control solenoid and associated wiring harness for obvious damage. On used excavators, check for harness wear at the pump mounting area and where cables route along the frame. Look for oil contamination on connectors, which indicates seal failures.

Step 2: Electrical Testing Using a multimeter, measure solenoid coil resistance (typically 3-7 ohms for Komatsu solenoids). Disconnect the solenoid connector and check for supply voltage (should read 12-24V depending on system). Test ECM output using Komatsu diagnostic software (KOMTRAX or KDW) to verify command signals.

Step 3: Circuit Verification Inspect connector pins for corrosion or bent terminals—a frequent issue in older machines. Check ground continuity from solenoid body to chassis. Measure harness resistance between ECM and solenoid (should be less than 5 ohms).

Step 4: Component Replacement If electrical tests pass but the code persists, replace the pump control solenoid valve. For used excavators with high hours, consider replacing the entire connector pigtail to eliminate intermittent connection issues caused by terminal fatigue.

Disclaimer: This guide provides general diagnostic information. Always consult the official Komatsu service manual and consider professional technician assistance for complex electrical diagnostics and hydraulic system repairs.