CAT 345BL Won’t Walk or Swing: Diagnosing Hydraulic and Electrical Causes

[MikePhua]

Introduction
A Caterpillar 345BL excavator that starts and runs but won’t walk or swing can be frustrating and costly. Operators and mechanics often troubleshoot a combination of hydraulic and electrical issues to get the machine moving again.
Symptoms

• Engine starts and runs normally.
  
• No response from travel motors or swing motor.
  
• Hydraulic pumps may still be running but with no output to these circuits.
  

Possible Causes
Hydraulic Control Problems
If the main control valve is stuck or a pilot line is blocked, hydraulic flow to the travel and swing circuits may be interrupted. Contaminated fluid or failed solenoids are common culprits.
Electrical or Safety Interlock Issues
Modern excavators have electronic interlocks that prevent functions if safety switches are triggered. A failed seat switch, travel lock, or a bad wiring connection can disable travel and swing.
Pump Control Failure
If the pump is not stroking properly, hydraulic pressure won’t build for the swing or travel functions. This can be caused by stuck regulators or failed sensors.
Troubleshooting Tips

• Verify that all safety switches are functioning.
  
• Inspect fuses and wiring to the control solenoids.
  
• Check hydraulic pilot pressures at the control valve.
  
• Inspect the control valve for stuck spools or debris.
  
• Confirm pump output and look for signs of regulator issues.
  

Conclusion
A 345BL that won’t walk or swing is usually suffering from an electrical interlock problem, a hydraulic control valve issue, or a pump control fault. Careful inspection of both electrical and hydraulic systems is necessary to pinpoint the failure and return the machine to full operation.