Sumitomo SH210-6 Fault Code 1621: Complete Diagnostic Guide

What is Sumitomo SH210-6 Fault Code 1621?

Fault Code 1621 on the Sumitomo SH210-6 excavator indicates a malfunction in the pump control solenoid circuit, specifically related to abnormal voltage or current flow in the main hydraulic pump's electronic control system. This code is triggered when the Engine Control Module (ECM) detects an electrical issue preventing proper communication with the pump's proportional solenoid valve.

This fault is critical because the pump control solenoid directly regulates hydraulic flow and pressure based on operator input and load demands. When this circuit fails, the excavator's hydraulic performance becomes compromised, affecting everything from swing speed to digging force. On older SH210-6 models, this code often appears due to wiring degradation or connector corrosion rather than actual solenoid failure.

Common Symptoms

When Code 1621 activates, operators typically experience:

• Reduced hydraulic power across all functions, with noticeably slower cycle times
• Erratic pump response or inconsistent pressure during combined operations (e.g., boom lift while swinging)
• Check engine light or warning indicator illuminated on the instrument cluster
• Intermittent loss of hydraulic power that may restore temporarily after machine restart
• Unusual hydraulic whine or pressure fluctuations during normal operation

Potential Causes

The most common technical causes for Code 1621 on used SH210-6 excavators include:

• Damaged wiring harness near the main pump, particularly where the harness contacts the engine block or frame (known wear point on this model)
• Corroded or loose connector pins at the pump solenoid connection, especially on machines operated in wet or coastal environments
• Failed pump control solenoid due to internal coil breakdown or contamination from hydraulic fluid ingress
• ECM voltage supply issues affecting the 12V reference circuit to the solenoid
• Shorted or open circuit in the solenoid control wiring between the ECM and pump assembly

How to Troubleshoot and Fix Code 1621

Step 1: Visual Inspection Begin by inspecting the wiring harness running from the ECM to the main hydraulic pump. On used excavators, check for rubbing points where the harness passes near the engine or hydraulic lines. Look for cracked insulation, exposed wires, or signs of previous repairs. Examine the connector at the pump solenoid for corrosion, bent pins, or moisture intrusion.

Step 2: Electrical Testing Using a digital multimeter, disconnect the pump solenoid connector and measure resistance across the solenoid coil. Typical specifications are 8-15 ohms (consult your service manual for exact values). Next, check for continuity in the wiring harness from the ECM connector to the pump solenoid. Measure voltage supply at the connector with the key on—you should see approximately 12V on the power supply wire.

Step 3: Component Testing and Replacement If wiring and voltage checks pass, test the solenoid function using Sumitomo's diagnostic software or a compatible scan tool to command the solenoid on/off while monitoring current draw. Abnormal current (typically should be 0.8-1.2A) indicates solenoid failure. For used machines, always clean connectors with electrical contact cleaner and apply dielectric grease before reconnecting. Replace the solenoid only after confirming wiring integrity, as premature component replacement is common with this code.

Disclaimer: This guide provides general troubleshooting information. Always consult the manufacturer's service manual for your specific machine serial number and seek qualified technician assistance for complex electrical diagnostics or repairs.