What is Case CX210C Fault Code 602?

Fault Code 602 on the Case CX210C excavator indicates a Pump Solenoid Valve Circuit Malfunction in the hydraulic system's electronic control circuit. This Diagnostic Trouble Code (DTC) is triggered when the Engine Control Module (ECM) detects an abnormal voltage or current reading from the hydraulic pump solenoid valve, which regulates hydraulic flow and pressure throughout the machine's systems.

This code is critical for the CX210C because the pump solenoid directly controls the variable displacement hydraulic pump's output. When this circuit malfunctions, the ECM cannot properly modulate hydraulic power delivery, affecting boom, arm, bucket, and swing functions. On used excavators, this fault often stems from electrical degradation rather than mechanical pump failure, making proper diagnosis essential before costly component replacement.

Common Symptoms

• Reduced hydraulic power across all functions, with noticeably slower cycle times for boom and arm movements
• Erratic hydraulic response where implements may operate normally then suddenly lose power or respond sluggishly
• Warning light activation on the instrument cluster, often accompanied by a diagnostic code display
• Machine may enter derate mode, limiting engine RPM to protect the hydraulic system from damage
• Intermittent fault behavior where the code appears during cold starts or after prolonged operation, then clears temporarily

Potential Causes

The most common causes for Code 602 on used CX210C excavators include:

• Damaged wiring harness near the hydraulic pump area where cables rub against the pump housing or frame—a known wear point on machines with 3,000+ hours
• Corroded or loose connector pins at the pump solenoid valve connection, especially on machines operated in wet or coastal environments
• Failed pump solenoid valve coil, typically showing resistance outside the 8-15 ohm specification range
• ECM internal circuit failure affecting the solenoid driver circuit (less common but possible on older machines)
• Voltage supply issues from the main power harness, including poor grounds at the pump mounting bracket
• Previous repair attempts using non-OEM solenoids with incorrect electrical specifications

How to Troubleshoot and Fix Code 602

Step 1: Visual Inspection and Connector Check Begin by accessing the hydraulic pump solenoid valve located on the main pump assembly. Disconnect the electrical connector and inspect for corrosion, bent pins, or moisture intrusion. Clean contacts with electrical contact cleaner and check for physical damage to the wiring harness, particularly where it routes near moving components or sharp edges.

Step 2: Electrical Testing with Multimeter Using a digital multimeter, measure the solenoid coil resistance directly at the valve terminals (connector disconnected). The specification should read between 8-15 ohms at room temperature. Next, check for supply voltage at the harness connector with the key on—you should see approximately 12 volts. Test the ground circuit by measuring resistance between the ground pin and a known good chassis ground (should be less than 1 ohm).

Step 3: Dynamic Circuit Testing Reconnect the solenoid and use a Case diagnostic software tool (ServiceMaster or equivalent) to command the solenoid on/off while monitoring actual current draw. The ECM should show 0.8-1.2 amps when energized. If voltage and resistance are correct but current draw is abnormal, the ECM driver circuit may be faulty. For used excavators, also perform a "wiggle test" on the harness while monitoring the code—intermittent shorts often reveal themselves during movement.

Step 4: Component Replacement and Verification If testing confirms a failed solenoid, replace with an OEM Case solenoid valve (aftermarket units often have incorrect electrical characteristics causing repeat failures). When installing, apply dielectric grease to connector pins and secure the harness with new zip ties away from wear points. Clear codes, perform a hydraulic system calibration using diagnostic software, and operate the machine through full function cycles to verify repair.

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Disclaimer: This guide provides general troubleshooting information for Case CX210C excavators. Hydraulic and electrical system diagnostics require proper training and specialized tools. Always consult the manufacturer's service manual and consider professional assistance for complex repairs, especially on used equipment where multiple underlying issues may exist.