What is Komatsu PC110-8M0 Fault Code CA351?

Fault Code CA351 on the Komatsu PC110-8M0 excavator indicates a malfunction in the hydraulic pump solenoid valve circuit, specifically detecting an abnormal electrical signal or open circuit condition in the pump control system. This code is triggered when the Electronic Control Module (ECM) detects voltage irregularities or fails to receive proper feedback from the pump flow control solenoid.

This fault directly impacts the machine's ability to regulate hydraulic pump output, which is critical for coordinating engine speed with hydraulic demand. The PC110-8M0 uses an electronically-controlled variable displacement pump system that relies on precise solenoid operation to optimize fuel efficiency and hydraulic performance. When CA351 activates, the system typically defaults to a mechanical backup mode, reducing operational efficiency and potentially causing erratic hydraulic response during multi-function operations.

Common Symptoms

• Amber or red warning light illuminated on the instrument cluster, often accompanied by a diagnostic trouble code display
• Reduced hydraulic power or sluggish operation, particularly noticeable during combined functions (boom + swing simultaneously)
• Increased fuel consumption as the system cannot optimize pump displacement based on load demand
• Intermittent loss of fine control during precision digging or grading work
• Engine may operate at higher RPM than necessary for the work being performed, indicating pump control failure

Potential Causes

The most common technical failures triggering CA351 on used PC110-8M0 machines include:

• Failed pump control solenoid valve due to internal coil deterioration or contaminated hydraulic oil causing stuck valve operation
• Damaged wiring harness at known rub points near the pump assembly, particularly where cables contact the pump housing during engine vibration
• Corroded or loose connector pins at the solenoid connector (C-352 connector) exposed to hydraulic oil mist or moisture intrusion
• ECM internal fault or corrupted software calibration, more common in machines with 8,000+ operating hours
• Low voltage supply issues from aging battery connections or alternator output problems affecting solenoid activation voltage
• Hydraulic contamination causing mechanical binding of the solenoid spool, creating electrical overcurrent conditions

How to Troubleshoot and Fix Code CA351

Step 1: Initial Electrical Verification

Connect a digital multimeter to the pump solenoid connector (disconnected from harness). Measure solenoid coil resistance; specification should be 10-15 ohms at 20°C. Values outside this range indicate solenoid replacement is necessary. On used excavators, also inspect the connector pins for green corrosion, bent terminals, or oil contamination—clean with electrical contact cleaner if found.

Step 2: Harness and Voltage Testing

With ignition on (engine off), backprobe the harness-side connector and verify supply voltage. You should see 24V (±2V) on the power supply pin. Check ground circuit resistance to chassis ground (should be less than 1 ohm). Inspect the wiring harness routing from the ECM to the pump, paying special attention to areas where the harness passes near rotating components or sharp edges—this model has known harness wear near the pump mounting bracket.

Step 3: Functional Testing and Hydraulic Inspection

If electrical tests pass, connect Komatsu KOMTRAX diagnostic software or compatible scanner to monitor real-time solenoid command versus actual current draw. The ECM should pulse the solenoid at varying duty cycles during operation. Compare actual current to commanded values. For used machines, drain a hydraulic oil sample and check for metallic contamination indicating pump wear—debris can jam the solenoid spool. If contamination is present, replace hydraulic oil filter, flush the system, and replace the solenoid assembly.

Step 4: ECM and Software Considerations

Clear the fault code and perform a cold start test cycle. If CA351 returns immediately without load, suspect ECM programming or internal module failure. Verify software version matches Komatsu's latest update for the PC110-8M0 platform, as earlier versions had known issues with pump control calibration.

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Disclaimer: This guide provides general diagnostic information. Hydraulic systems operate under extreme pressure and incorrect repairs can cause serious injury. Always consult the official Komatsu service manual for your specific serial number and consider professional assistance from a certified technician for complex electrical or hydraulic diagnostics.