What is Kobelco SK210-6E Fault Code B-6?

Fault Code B-6 on the Kobelco SK210-6E indicates a malfunction in the Boom Raise Circuit, specifically a short circuit or abnormal electrical signal detected in the boom raise solenoid valve wiring or control circuit. This code is triggered when the excavator's Electronic Control Module (ECM) detects voltage levels outside the expected parameters in the boom raise control system.

This fault is critical for the SK210-6E because the boom circuit controls one of the most fundamental hydraulic functions of the machine. When this code is active, the ECM may limit boom operations to prevent hydraulic system damage or unpredictable machine behavior. On used excavators, this code frequently appears due to age-related deterioration of wiring harnesses and connectors exposed to harsh operating environments.

Common Symptoms

• Boom raise function becomes erratic or completely inoperative while other hydraulic functions may still work normally
• Intermittent loss of boom control, especially during initial startup or after the machine has been sitting idle
• Monitor panel displays warning light or error message specifically indicating a hydraulic system fault
• Reduced boom lift speed or weak lifting performance even when engine RPM is normal
• Solenoid clicking sounds near the main control valve without corresponding boom movement

Potential Causes

The most common technical causes for Code B-6 on used SK210-6E excavators include:

• Damaged or corroded wiring harness between the ECM and boom raise solenoid valve, particularly at known rub points near the swing bearing and along the boom base
• Failed boom raise solenoid valve coil due to internal short circuit or insulation breakdown (common in machines with 5,000+ operating hours)
• Corroded or loose electrical connectors at the solenoid valve or ECM terminals caused by water intrusion
• Faulty ECM output circuit for the boom raise function, though less common than wiring issues
• Grounding issues where chassis ground points have corroded or loosened over time

How to Troubleshoot and Fix Code B-6

Step 1: Visual Inspection Begin by inspecting the boom raise solenoid valve wiring harness from the ECM to the main control valve. On used excavators, pay special attention to areas where the harness routes near moving components or sharp edges. Check all connectors for corrosion, moisture, or bent pins. Clean connectors with electrical contact cleaner and ensure they click firmly into place.

Step 2: Resistance and Continuity Testing Disconnect the boom raise solenoid connector and measure coil resistance using a digital multimeter. Typical resistance should be between 20-50 ohms (consult your service manual for exact specifications). Check for continuity in all wiring from the solenoid back to the ECM connector. Any reading of infinite resistance indicates an open circuit requiring harness repair or replacement.

Step 3: Voltage Supply Testing With the ignition on and the boom raise control activated, measure voltage at the solenoid connector. You should see battery voltage (approximately 12-14V) when the control is engaged. No voltage indicates an ECM output problem or wiring fault. Inconsistent voltage suggests poor connections or damaged wiring.

Step 4: Solenoid Replacement and Verification If wiring tests pass but the solenoid shows incorrect resistance or fails to operate with proper voltage, replace the boom raise solenoid valve. For used machines, consider replacing the entire connector pigtail along with the solenoid to ensure reliable connections. After replacement, clear the fault code using Kobelco diagnostic software or by disconnecting the battery for 5 minutes, then test boom operation through full range of motion.

Disclaimer: This guide provides general troubleshooting information for experienced technicians. Always consult the official Kobelco service manual for your specific machine serial number and consider professional diagnostic assistance for complex electrical issues or if you're unfamiliar with hydraulic systems.