Kobelco ED150 Two-Speed Travel Solenoid Failure and Diagnostic Strategy

[MikePhua]

Quick answer
A 2007 Kobelco ED150 Blade Runner excavator displaying intermittent loss of travel speed and a two-speed solenoid error likely suffers from a faulty solenoid coil, poor electrical connection, or hydraulic contamination. Locating and testing the solenoid near the travel valve block is the first step toward restoring consistent two-speed function.
Kobelco ED150 Blade Runner background and travel system design
The Kobelco ED150 Blade Runner is a specialized 15-ton class excavator equipped with a full-width dozer blade and enhanced undercarriage for grading and mobility. Introduced in the mid-2000s, it was designed for contractors needing both excavation and finish grading in a single machine.
Key features include:

• Isuzu 4-cylinder turbo diesel engine
  
• Two-speed travel system with electronic solenoid control
  
• Hydraulic pilot-operated joystick controls
  
• Blade integrated with the main frame for stability
  
• Travel valve block mounted near the center frame
  

The two-speed travel system allows the operator to switch between low torque/high traction and high speed for repositioning. This is controlled by a solenoid valve that shifts hydraulic flow to the travel motors.
Symptoms and intermittent failure behavior
In the reported case, the machine occasionally runs normally but later loses travel speed entirely. The onboard diagnostics display a two-speed solenoid error. This suggests that the solenoid is either:

• Not receiving electrical signal
  
• Failing to shift internally
  
• Stuck due to contamination or wear
  

Intermittent behavior points to a marginal failure—such as a cracked coil winding, corroded connector, or sticky spool.
Locating and testing the solenoid
The two-speed solenoid is typically mounted on or near the travel valve block, which is located under the cab or near the hydraulic pump manifold. To inspect:

• Remove the floor plate or side panel to access the valve block
  
• Identify the solenoid by its electrical connector and cylindrical coil body
  
• Disconnect the plug and inspect for corrosion or bent pins
  
• Use a multimeter to test coil resistance—should read 10–20 ohms
  
• Apply 12V power directly to the coil and listen for a click
  
• If no click is heard, the solenoid is likely seized or burned out
  

Replacement solenoids are available from Kobelco dealers or hydraulic component suppliers. Always match the part number and verify voltage rating.
Electrical and hydraulic troubleshooting tips

• Check fuse and relay associated with travel control circuit
  
• Inspect wiring harness for abrasion or loose connectors
  
• Clean solenoid spool and bore with brake cleaner if sticking is suspected
  
• Replace hydraulic filters and test for contamination
  
• Monitor travel pressure during operation—low pressure may indicate valve blockage
  

One technician in Alberta resolved a similar issue by replacing the solenoid and cleaning the valve block. He noted that the machine had been parked for months, and moisture had corroded the connector pins.
Preventive maintenance and reliability recommendations

• Cycle two-speed travel weekly to prevent spool sticking
  
• Use dielectric grease on electrical connectors
  
• Replace hydraulic fluid every 1,000 hours or annually
  
• Keep undercarriage clean to prevent debris from entering valve block
  
• Label solenoid connectors for easier future diagnostics
  

Conclusion
The two-speed travel error on a Kobelco ED150 is most often caused by a failing solenoid coil or poor electrical connection. With careful inspection, resistance testing, and hydraulic cleaning, the issue can be resolved without major disassembly. Preventive care and regular cycling of the travel system will ensure long-term reliability.