Komatsu PC100-6 Fault Code E208: Complete Diagnostic Guide

What is Komatsu PC100-6 Fault Code E208?

Fault Code E208 indicates a malfunction in the hydraulic pump solenoid valve circuit, specifically detecting abnormal voltage or an open/short circuit condition in the pump control system. This code is generated when the engine control module (ECM) detects improper electrical signals from the proportional solenoid valve that regulates hydraulic pump displacement and flow.

This fault is critical for the PC100-6 because the pump control solenoid directly affects hydraulic system efficiency, fuel consumption, and overall machine performance. When E208 triggers, the ECM typically forces the hydraulic system into a default "limp mode," limiting pump output to protect components from damage.

Common Symptoms

• Yellow warning light illuminated on the instrument panel, often accompanied by reduced hydraulic power
• Noticeably sluggish boom, arm, or bucket movements due to restricted pump flow
• Increased fuel consumption as the system struggles to compensate for improper pump control
• Intermittent loss of hydraulic power, particularly during warm-up or under heavy load conditions
• Engine RPM fluctuations when operating multiple hydraulic functions simultaneously

Potential Causes

The most common technical failures triggering E208 on used PC100-6 excavators include:

• Solenoid coil failure due to age-related insulation breakdown or internal short circuits (resistance should measure 18-22 ohms)
• Harness chafing at the main pump area where wiring runs alongside the swivel joint—a known wear point on this model
• Corroded or loose connector pins at the solenoid plug (C-147 connector), especially in machines operating in wet conditions
• ECM internal driver circuit failure, less common but possible in high-hour units (8,000+ hours)
• Voltage supply issues from damaged main power harness or poor grounding at frame connection points

How to Troubleshoot and Fix Code E208

Step 1: Visual Inspection Inspect the pump solenoid wiring harness from the ECM to the solenoid valve. On used PC100-6 models, check for abraded insulation where the harness passes near the hydraulic pump mounting bracket. Examine the C-147 connector for corrosion, bent pins, or moisture intrusion.

Step 2: Electrical Testing Using a digital multimeter, disconnect the solenoid connector and measure coil resistance (should be 18-22 ohms at 20°C). Check for supply voltage at the harness side with ignition on (should read 12V). Measure resistance to ground on both solenoid wires—infinite resistance indicates proper insulation.

Step 3: Circuit Verification With the solenoid connected, backprobe the connector and monitor voltage while operating hydraulics. Voltage should fluctuate between 0-12V as the ECM modulates control. If voltage remains constant or reads 0V, suspect ECM driver failure. For used machines, verify ground continuity from ECM to chassis (should be <1 ohm).

Step 4: Component Replacement Replace the solenoid valve if resistance is out of specification. When installing on used excavators, apply dielectric grease to connector pins and secure harness away from abrasion points using new zip ties.

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Disclaimer: This guide provides general diagnostic information. Complex electrical issues may require Komatsu-specific diagnostic software (KOMTRAX) and trained technicians. Always consult qualified personnel for repairs involving ECM replacement or hydraulic system modifications.