What is Komatsu PC110-7 Fault Code E-3?

Komatsu PC110-7 Fault Code E-3 indicates a malfunction in the hydraulic pump solenoid valve circuit or the proportional pressure control system. This diagnostic trouble code specifically relates to an electrical abnormality detected by the machine's Electronic Control Module (ECM) when monitoring the hydraulic system's proportional control solenoid. The code triggers when the controller detects an open circuit, short circuit, or abnormal resistance in the pump control solenoid wiring or valve itself.

This fault is critical for the PC110-7 because the proportional pressure control solenoid directly regulates hydraulic pump output based on operator input. When this system fails, the excavator loses precise hydraulic control, dramatically affecting productivity and operational safety on used machines where electrical connections may have deteriorated over time.

Common Symptoms

When Code E-3 is active on your Komatsu PC110-7, operators typically experience:

• Loss of hydraulic power or sluggish boom, arm, and bucket response across all functions
• Erratic hydraulic performance with inconsistent swing or digging force
• Warning indicator light illuminated on the monitor panel, often accompanied by error message display
• Intermittent electrical fault that may come and go, especially when the machine vibrates or operates on uneven terrain
• Complete hydraulic system shutdown in severe cases, forcing the operator to restart the machine

Potential Causes

The most common technical causes for E-3 fault codes on used PC110-7 excavators include:

• Corroded or damaged wiring harness connectors at the pump solenoid valve, particularly where the harness routes near the hydraulic pump mounting area
• Failed proportional pressure control solenoid valve due to internal coil breakdown or mechanical wear from contaminated hydraulic oil
• Broken or frayed wires in the main engine harness, especially at known rub points near the pump assembly
• Faulty ECM connections or poor ground circuits causing voltage irregularities
• Water intrusion into electrical connectors from damaged seals or cab leaks common in older machines
• Aftermarket repair damage from previous owners attempting DIY fixes without proper wiring diagrams

How to Troubleshoot and Fix Code E-3

Step 1: Initial Diagnostic Scan Connect a Komatsu diagnostic tool (KOMPCS or compatible aftermarket scanner) to retrieve active and pending codes. Record freeze frame data showing voltage readings when the fault occurred. This baseline information is essential for used equipment diagnosis.

Step 2: Visual Harness Inspection Physically inspect the wiring harness from the ECM to the hydraulic pump solenoid valve. On used PC110-7 machines, check the harness routing along the engine mount side for wear points where cables contact metal brackets. Look for chafed insulation, oil contamination, or burned wires indicating short circuits.

Step 3: Connector and Ground Testing Disconnect the solenoid valve connector at the pump assembly. Inspect pins for corrosion, bent terminals, or moisture intrusion—extremely common in 10+ year-old excavators. Clean connections with electrical contact cleaner and apply dielectric grease. Test the ground circuit resistance; it should read less than 1 ohm to chassis ground.

Step 4: Solenoid Resistance Testing Using a digital multimeter, measure resistance across the solenoid terminals. Typical specification for the PC110-7 pump solenoid is 3-5 ohms at 20°C. Readings outside this range indicate solenoid coil failure requiring valve replacement.

Step 5: Live Voltage Testing With the ignition on (engine off), backprobe the solenoid connector to measure supply voltage. You should see approximately 12V battery voltage. If voltage is present but the solenoid doesn't activate when commanded through the diagnostic tool, replace the solenoid valve assembly.

Step 6: Advanced ECM Testing If all external circuits test correctly, the fault may lie within the ECM output driver circuit. This requires specialized testing equipment and often warrants professional consultation, especially for used machines where ECM replacement costs can exceed $2,000.

For used excavators, always verify that hydraulic oil contamination hasn't damaged internal solenoid components before replacing electrical parts. Metal particles from worn pumps can jam solenoid plungers while showing normal electrical resistance.

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Disclaimer: This guide provides general troubleshooting information for informational purposes. Always consult the official Komatsu service manual for your specific serial number and consider professional diagnostic assistance for complex electrical issues. Improper repairs may cause additional damage or safety hazards.