What is Kobelco SK140LC-8 Fault Code 20108?

Fault Code 20108 on the Kobelco SK140LC-8 excavator indicates a malfunction in the hydraulic pump solenoid control circuit, specifically related to the main pump's electronic proportional control system. This diagnostic trouble code (DTC) is triggered when the Engine Control Module (ECM) detects an abnormal voltage or resistance reading from the pump solenoid valve circuit, preventing optimal hydraulic flow regulation.

This code is critical for the SK140LC-8's performance because the hydraulic pump solenoid directly controls variable displacement pump output. When this circuit malfunctions, the excavator cannot properly adjust hydraulic pressure and flow based on operational demands, resulting in reduced efficiency, sluggish responses, and potential hydraulic system damage. For used excavators, this fault often stems from electrical degradation rather than mechanical pump failure.

Common Symptoms

Operators experiencing Code 20108 may notice:

• Reduced hydraulic power across all functions (boom, arm, bucket movements significantly slower than normal)
• Engine warning light or malfunction indicator illuminated on the instrument panel
• Erratic hydraulic response with inconsistent speeds during combined operations
• Engine derate mode where RPM is automatically limited to prevent system damage
• Increased fuel consumption due to improper pump displacement control

Potential Causes

The most frequent technical causes for this fault code include:

• Damaged wiring harness near the pump mounting area where vibration causes wire chafing (common wear point on SK140LC-8 models)
• Corroded electrical connectors at the pump solenoid, especially on machines operating in wet or coastal environments
• Failed proportional solenoid valve due to internal coil breakdown or contaminated hydraulic fluid affecting valve operation
• ECM voltage supply issues from degraded ground connections or power distribution problems
• Intermittent short circuits in the control harness from rodent damage or improper previous repairs

How to Troubleshoot and Fix Code 20108

Step 1: Visual Inspection and Connection Check Begin by disconnecting the battery and inspecting the pump solenoid connector for corrosion, moisture, or bent pins. On used excavators, this connector frequently shows green oxidation. Clean contacts with electrical contact cleaner and apply dielectric grease. Trace the wiring harness from the ECM to the pump, checking for abrasion points where the harness contacts the frame or hydraulic lines.

Step 2: Electrical Testing with Multimeter Using a digital multimeter, measure solenoid coil resistance at the pump connector (should typically read 8-15 ohms; consult service manual for exact specification). Test supply voltage from the ECM with ignition on (should show 12-14V). Check for continuity in both control wires and verify proper grounding with less than 1 ohm resistance to chassis ground.

Step 3: Advanced Diagnostics and Component Testing Connect Kobelco diagnostic software (TCMS or compatible scan tool) to monitor real-time solenoid command values versus actual performance. Perform an actuator test to command the solenoid while monitoring current draw (typically 0.8-1.2 amps). For used machines, replace the solenoid only after confirming wiring integrity—premature component replacement is common when harness issues are the actual culprit.

Disclaimer: This guide provides general troubleshooting information. Always consult the Kobelco SK140LC-8 service manual for exact specifications and safety procedures. Complex electrical diagnostics should be performed by certified technicians with proper equipment.