What is Komatsu PC100-6 Fault Code E-7?

Komatsu PC100-6 Fault Code E-7 indicates a hydraulic pump solenoid valve malfunction or electrical circuit abnormality in the main pump control system. This code specifically relates to the proportional pressure control solenoid that regulates hydraulic pump displacement based on load demand. The Electronic Control Unit (ECU) detects either an open circuit, short circuit, or abnormal resistance in the pump control solenoid circuit, which directly impacts the excavator's ability to match engine power with hydraulic output efficiently.

This fault is critical for the PC100-6 because it compromises the load-sensing hydraulic system that optimizes fuel consumption and operational performance. When this code activates, the machine typically defaults to a fail-safe mode with reduced hydraulic flow.

Common Symptoms

• Illuminated warning lamp on the instrument panel with simultaneous loss of hydraulic power
• Reduced swing and digging force across all hydraulic functions, particularly noticeable during combined operations
• Engine overspeeding during light loads due to improper pump displacement control
• Erratic hydraulic response with inconsistent cycle times and jerky movements
• Increased fuel consumption as the system cannot properly match pump output to actual demand

Potential Causes

On used PC100-6 excavators, E-7 typically stems from age-related deterioration. The pump solenoid connector located near the main hydraulic pump frequently suffers from corrosion due to hydraulic oil mist and moisture infiltration. Harness chafing against the pump housing is common at approximately 5,000-8,000 operating hours, causing intermittent short circuits.

The solenoid coil itself may develop internal breaks or resistance changes (normal specification: 18-22 ohms at 20°C). ECU relay failures within the controller can also trigger this code. In used machines, previous repair attempts sometimes leave inadequate wire splices that fail under vibration stress.

How to Troubleshoot and Fix Code E-7

Step 1: Visual Inspection Inspect the pump solenoid connector and wiring harness for physical damage, oil contamination, or corrosion. Check for harness routing issues where cables contact moving parts or hot surfaces.

Step 2: Electrical Testing Using a digital multimeter, measure solenoid resistance at the connector (should read 18-22 ohms). Check supply voltage from the ECU (should be 12V with key on). Verify ground circuit continuity (less than 1 ohm resistance).

Step 3: Connector Service Clean connector terminals with electrical contact cleaner and apply dielectric grease. On used excavators, corrosion at pin connections accounts for 40% of E-7 codes without actual component failure.

Step 4: Solenoid Replacement If resistance or voltage readings fail specification, replace the pump control solenoid (Komatsu part number 702-21-55901). Ensure proper torque specifications and secure harness routing.

Step 5: System Reset Clear fault codes using Komatsu diagnostic software (KOMTRAX or compatible scanner) and perform functional testing under load.

Disclaimer: This guide provides general diagnostic procedures. Always consult certified Komatsu technicians for complex hydraulic system repairs and refer to the official service manual for your specific machine serial number.