What is Sumitomo SH240-6 Fault Code 602?

Fault Code 602 on the Sumitomo SH240-6 excavator indicates a malfunction in the hydraulic pump solenoid valve circuit, specifically related to abnormal electrical current or voltage detected by the machine's Electronic Control Unit (ECU). This code typically signals that the pump flow control solenoid is either receiving insufficient power, experiencing a short circuit, or has failed internally.

The Sumitomo SH240-6 relies on precise electronic control of its hydraulic pump displacement to optimize fuel efficiency and hydraulic performance. The solenoid valve modulates pump output based on operator demand and system pressure. When the ECU detects electrical irregularities in this circuit, it triggers Code 602 to prevent hydraulic system damage. This is critical because improper pump control can lead to overheating, reduced digging force, or complete hydraulic failure—severely impacting productivity on job sites.

Common Symptoms

When Code 602 is active, operators typically experience:

• Reduced hydraulic power across all functions (boom, arm, bucket, and swing movements feel sluggish)
• Illuminated warning light on the instrument panel, often accompanied by an audible alarm
• Engine derate mode where the machine limits RPM to protect the hydraulic system
• Erratic hydraulic response with inconsistent cycle times or jerky movements
• Increased fuel consumption due to inefficient pump operation trying to compensate for control issues

Potential Causes

The most common technical reasons for Code 602 on used SH240-6 excavators include:

• Failed pump solenoid valve due to internal coil burnout or mechanical sticking from contaminated hydraulic fluid
• Damaged wiring harness between the ECU and pump solenoid, particularly at flex points near the engine mount or pump housing where vibration causes conductor breakage
• Corroded electrical connectors on the solenoid valve plug, especially in machines operated in wet or coastal environments
• Low voltage supply from a weak battery or failing alternator affecting solenoid operation
• ECU calibration errors or software corruption (less common but possible after improper jump-starting)
• Hydraulic fluid contamination causing the solenoid spool to bind mechanically while electrical values remain normal

How to Troubleshoot and Fix Code 602

Step 1: Visual Inspection and Connector Check Begin by locating the hydraulic pump solenoid valve on the main pump assembly. Disconnect the electrical connector and inspect for corrosion, bent pins, or moisture intrusion. On used excavators, this connector often shows green corrosion due to years of heat cycling. Clean contacts with electrical contact cleaner and apply dielectric grease before reconnecting.

Step 2: Electrical Testing with Multimeter Using a digital multimeter, measure solenoid coil resistance at the valve connector (ECU side disconnected). Typical resistance should be 10-30 ohms (consult your service manual for exact specs). Infinite resistance indicates an open coil (failed solenoid). Next, check for supply voltage at the harness connector with the ignition on—you should see battery voltage (12V). No voltage indicates a wiring harness break or ECU output failure.

Step 3: Harness Continuity and Insulation Testing Trace the wiring from the solenoid back to the ECU, checking for chafed insulation at known rub points: near the engine vibration dampeners, along the pump mounting bracket, and where the harness passes through bulkhead grommets. Use the multimeter's continuity function to verify circuit integrity. For used machines, pay special attention to heat-damaged wiring near exhaust components.

Step 4: Solenoid Replacement or Hydraulic Fluid Service If electrical tests pass but the code persists, the solenoid may be mechanically stuck. Before replacement, check hydraulic fluid condition—contaminated oil with metal particles suggests the solenoid spool is binding. Perform a hydraulic fluid flush and filter replacement if contamination is present. If fluid is clean, replace the pump solenoid valve assembly with a genuine Sumitomo or OEM-equivalent part.

Step 5: Clear Codes and Functional Test After repairs, use Sumitomo diagnostic software (or a compatible scan tool) to clear Code 602 from ECU memory. Operate the machine through full hydraulic cycles under load, monitoring for code recurrence and verifying normal pump response.

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Disclaimer: This guide provides general diagnostic information for Code 602 on Sumitomo SH240-6 excavators. Hydraulic and electrical systems involve high pressures and voltages. Always consult the official Sumitomo service manual and consider professional assistance from certified heavy equipment technicians, especially when working on used machinery with unknown service history.