Sumitomo SH220LC-6 Fault Code 1093: Technical Guide and Repair Solutions

What is Sumitomo SH220LC-6 Fault Code 1093?

Fault Code 1093 on the Sumitomo SH220LC-6 indicates a malfunction in the hydraulic pump solenoid valve circuit, specifically related to abnormal electrical resistance or an open/short circuit condition in the pump control system. This diagnostic trouble code (DTC) is generated when the Electronic Control Module (ECM) detects voltage or current values outside the manufacturer's specified parameters for the main hydraulic pump's proportional solenoid valve.

This code is critical because the hydraulic pump solenoid valve directly controls the pump displacement and flow rate, which affects all hydraulic functions including boom, arm, bucket, and swing operations. The Sumitomo SH220LC-6's load-sensing hydraulic system relies on precise electronic control to optimize fuel efficiency and performance. When this circuit fails, the machine may enter a protective derate mode to prevent damage to the hydraulic system or engine.

Common Symptoms

When Code 1093 is active, operators typically experience:

• Reduced hydraulic power across all functions, with sluggish boom and arm movements
• Illuminated warning lamp on the instrument panel (often amber/yellow)
• Erratic pump response or inconsistent flow during combined operations
• Engine over-revving without corresponding hydraulic output due to pump displacement control failure
• Complete loss of hydraulic function in severe cases where the system defaults to minimum displacement

Potential Causes

The most common technical failures triggering Code 1093 on used SH220LC-6 excavators include:

• Solenoid valve coil failure due to internal winding breakdown (resistance typically measures 8-12 ohms when functional)
• Wiring harness damage at flex points near the pump mounting area, particularly where the harness routes over the pump housing
• Connector corrosion at the 3-pin Deutsch connector on the pump solenoid valve assembly
• ECM internal driver circuit failure affecting the solenoid output channel
• Voltage supply issues from the main power relay or blown fuses in the control circuit
• Hydraulic contamination causing mechanical binding of the solenoid spool valve

How to Troubleshoot and Fix Code 1093

Step 1: Visual Inspection and Connector Check Begin by accessing the main hydraulic pump on the left side of the engine. Disconnect the 3-pin solenoid connector and inspect for bent pins, moisture intrusion, or green corrosion. On used machines, this connector frequently suffers from oil contamination. Clean with electrical contact cleaner and apply dielectric grease before reconnection.

Step 2: Resistance and Voltage Testing Using a digital multimeter (DMM), measure the solenoid coil resistance between the two power pins (with connector disconnected). Specifications should read 8-12 ohms at 20°C. Values below 5 ohms indicate a short circuit; readings above 15 ohms or infinite resistance confirm an open circuit requiring solenoid replacement. Next, check supply voltage at the connector with ignition on: you should see 12-14 volts DC on the power supply pin.

Step 3: Harness Continuity and Ground Testing Trace the solenoid harness from the pump back to the ECM connector (typically located under the operator's cab). Check for continuity on all three wires and verify less than 1 ohm resistance to confirm no breaks. Inspect harness routing for rub-through points where the harness contacts the pump body or hydraulic lines—a common failure point on machines with 5,000+ hours.

Step 4: Functional Testing and Code Clearing If all electrical values are within specification, the issue may be mechanical binding within the solenoid valve itself. Consider removing and bench-testing the solenoid with a 12V power supply to verify smooth plunger movement. After repairs, clear the fault code using Sumitomo diagnostic software or a compatible J1939 scan tool, then perform a full hydraulic function test under load.

For used excavators, always inspect harness protective sleeving and replace zip ties that may have degraded, allowing wire movement and chafing. Check the ECM ground connections at the frame mounting points, as poor grounds frequently cause intermittent solenoid codes.

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Disclaimer: This guide provides general diagnostic information for Sumitomo SH220LC-6 excavators. Always consult the manufacturer's service manual for model-specific procedures and torque specifications. If you're uncomfortable performing electrical diagnostics or hydraulic system repairs, contact a certified Sumitomo technician or qualified heavy equipment mechanic to prevent further damage or safety hazards.