What is Komatsu PC110-8M0 Fault Code E-23?

Fault Code E-23 on the Komatsu PC110-8M0 indicates a hydraulic pump solenoid valve circuit malfunction, specifically related to the main pump control system's electrical circuit.

This diagnostic trouble code (DTC) signals that the Electronic Control Module (ECM) has detected an abnormal voltage or current flow in the hydraulic pump's proportional solenoid valve circuit. The PC110-8M0 utilizes an electronically-controlled hydraulic system where the ECM modulates pump displacement based on load demand. When the solenoid valve circuit fails to respond within manufacturer-specified parameters (typically 0.5-4.5 volts), Code E-23 triggers. This is critical because improper pump control directly affects hydraulic flow management, leading to reduced digging force, sluggish operation, and potential damage to the pump control servo piston assembly.

Common Symptoms

• Warning lamp illumination on the monitor panel with simultaneous hydraulic performance reduction
• Sluggish or erratic hydraulic response during boom, arm, or bucket operations, especially under load
• Intermittent loss of hydraulic power that may reset after machine restart but returns during operation
• Automatic engine RPM limitation (derate mode) preventing operation above 1800 RPM
• Excessive hydraulic system heat due to improper pump displacement control

Potential Causes

The most common technical failures causing E-23 on used PC110-8M0 excavators include:

• Proportional solenoid valve coil failure – internal winding open circuit or short (resistance should measure 8-12 ohms)
• Wiring harness damage at known rub points near the main pump mounting area where harness contacts frame members
• Corroded or moisture-contaminated connectors at the 6-pin solenoid connector (common in machines with 3,000+ operating hours)
• ECM internal driver circuit failure preventing proper solenoid energization
• Hydraulic pump control valve contamination causing mechanical binding that increases electrical load beyond ECM limits
• Damaged or pinched wiring between ECM (located under operator seat) and pump solenoid valve

How to Troubleshoot and Fix Code E-23

Step 1: Visual Inspection and Connector Check Begin by disconnecting the battery negative terminal. Locate the hydraulic pump solenoid connector on the right side of the main pump assembly. Inspect for corrosion, bent pins, or moisture intrusion. Clean contacts with electrical contact cleaner and apply dielectric grease. On used excavators, check the entire harness routing from ECM to solenoid for abraded insulation, particularly where harness passes through bulkheads.

Step 2: Solenoid Resistance Testing Using a digital multimeter (DMM), measure solenoid coil resistance at the valve connector (harness disconnected). Specification for PC110-8M0 is 8-12 ohms at 20°C. If reading shows open circuit (OL) or significantly lower resistance (<5 ohms), replace the proportional solenoid valve assembly (Komatsu Part #723-56-12101 or equivalent).

Step 3: Circuit Voltage and Wiring Verification Reconnect solenoid connector. With ignition ON/engine OFF, backprobe the solenoid supply wire (typically red/white stripe). You should measure approximately 12 volts DC. Start engine and observe voltage during operation – it should modulate between 0.5-4.5 volts as hydraulic demand changes. If voltage remains constant or shows no signal, suspect ECM output driver failure requiring ECM replacement or professional reprogramming.

Step 4: Harness Continuity Test If solenoid tests good but code persists, check harness continuity from ECM connector to solenoid connector using wiring diagram. Pay special attention to ground circuits – poor grounding is extremely common in used machines due to corrosion at chassis ground points.

Disclaimer: This guide provides general troubleshooting procedures. Always consult the official Komatsu PC110-8M0 service manual and follow proper lockout/tagout safety procedures. Complex electrical diagnostics may require factory-trained technicians with Komatsu diagnostic software (KOMTRAX Plus) for definitive ECM testing.