Komatsu PC400LC-6 Fault Code E208: Complete Diagnostic Guide

What is Komatsu PC400LC-6 Fault Code E208?

Fault Code E208 indicates a malfunction in the hydraulic pump control system, specifically related to the pump flow control solenoid valve circuit or its associated wiring harness. This code is triggered when the Electronic Control Module (ECM) detects an abnormal voltage or resistance reading from the pump control solenoid, which regulates hydraulic flow based on operational demands.

In the PC400LC-6 model, this system is critical for maintaining optimal hydraulic performance and fuel efficiency. The pump control solenoid adjusts the swash plate angle of the variable displacement hydraulic pump, directly affecting machine responsiveness and power delivery. When this circuit fails, the excavator may default to a fixed displacement mode, significantly impacting productivity.

Common Symptoms

When Code E208 is active, operators typically experience:

• Illuminated warning light on the monitor panel with error code display
• Reduced hydraulic power across all functions (boom, arm, bucket, swing)
• Sluggish machine response or delayed reaction to joystick inputs
• Increased fuel consumption due to inefficient pump operation
• Intermittent loss of hydraulic function during operation, particularly under heavy loads

Potential Causes

The most common technical reasons for E208 on used PC400LC-6 excavators include:

• Faulty pump control solenoid valve due to internal coil failure or mechanical wear
• Damaged wiring harness between the ECM and solenoid, especially at known rub points near the pump mounting area
• Corroded or loose electrical connectors at the solenoid or ECM interface
• Short circuit or open circuit in the solenoid valve wiring
• ECM internal fault (less common, but possible in high-hour machines)
• Low voltage supply from deteriorated battery or charging system issues

How to Troubleshoot and Fix Code E208

Step 1: Visual Inspection Begin by inspecting the pump control solenoid valve located on the main hydraulic pump. Check for physical damage, oil contamination on electrical connections, and verify the connector is fully seated. On used excavators, examine the wiring harness routing for signs of chafing against the pump body or frame—a common failure point on this model.

Step 2: Electrical Testing Using a digital multimeter, disconnect the solenoid connector and measure resistance across the solenoid coil terminals. Specification should be approximately 10-15 ohms (consult service manual for exact values). Next, check for voltage supply at the harness connector with ignition on—should read approximately 12-24V DC depending on system design.

Step 3: Circuit Continuity Check Test continuity between the ECM connector and solenoid harness. Check for shorts to ground or opens in the circuit. Pay special attention to connector pins for corrosion or bent terminals, common in machines operating in harsh environments.

Step 4: Component Replacement If resistance or voltage readings are out of specification, replace the faulty component. For used machines, always replace connector seals and apply dielectric grease to prevent future corrosion. Clear the code using Komatsu diagnostic software (KOMTRAX) or a compatible scan tool and perform a function test.

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