Resolving Auxiliary Hydraulic Malfunctions on the Bobcat T250

[MikePhua]

The T250 and Its Hydraulic Architecture
The Bobcat T250 compact track loader was introduced in the early 2000s as part of Bobcat’s high-performance lineup, offering a rated operating capacity of 2,500 lbs and a robust hydraulic system capable of powering demanding attachments. With a high-flow auxiliary circuit and electronic control integration, the T250 became a popular choice for contractors using augers, trenchers, and brush cutters. Its hydraulic system includes solenoid-controlled valves, pressure sensors, and a joystick interface that allows precise control over flow direction and speed.
Despite its reliability, the T250’s auxiliary hydraulics can develop quirks—especially when attachments are rarely used or when solenoids sit idle for extended periods.
Symptoms of Unintended Hydraulic Activation
A common issue occurs when an attachment, such as a post-hole auger, continues to operate even after the auxiliary function is turned off. In one case, the auger spun counterclockwise persistently—even after the machine was restarted and pressure was released. This behavior suggests a stuck or energized solenoid valve that fails to close properly, allowing fluid to bypass the control logic.
This type of malfunction can be confusing, especially when the joystick appears to be in the neutral position and the auxiliary switch is disengaged. It raises questions about whether there is a separate solenoid responsible for enabling the auxiliary circuit, or if the directional solenoids themselves are responsible for both flow initiation and direction.
Terminology Clarification

• Auxiliary Hydraulics: A secondary hydraulic circuit used to power attachments
  
• Solenoid Valve: An electrically actuated valve that controls fluid flow based on input signals
  
• PWM (Pulse Width Modulation): A method of controlling hydraulic flow by varying the duty cycle of voltage sent to a solenoid
  
• Joystick Control: The operator interface used to command hydraulic functions
  
• Flow Direction: The path hydraulic fluid takes through the attachment, determining rotation or movement
  

Diagnostic Codes and Joystick Behavior
When the malfunction persists, diagnostic codes may appear. In this case, codes 12-22 and 12-23 were triggered when the joystick was used while the auger spun on its own. These codes typically relate to joystick position errors or signal inconsistencies. While they may seem like the root cause, they are often symptoms of a deeper issue—such as a sticky valve stem or a solenoid that fails to de-energize.
Interestingly, the problem did not occur during initial operation, suggesting that the valve may have become stuck after its first use. This is common in machines where auxiliary hydraulics are rarely engaged, leading to varnish buildup or minor corrosion inside the valve body.
Field Repair and Resolution
The issue was resolved by removing and swapping the valve stems. This mechanical action freed the sticking components and restored normal function. The auger responded correctly to joystick input, and the persistent spinning ceased. While the diagnostic codes continued to appear intermittently, they were no longer associated with functional failure.
This outcome supports a broader principle in hydraulic troubleshooting: mechanical components that sit idle for long periods may require manual intervention to restore movement. Simply energizing the system may not be enough—physical cleaning or repositioning may be necessary.
Preventive Maintenance and Usage Tips
To prevent auxiliary hydraulic issues:

• Cycle auxiliary functions monthly, even if attachments are not in use
  
• Use dielectric grease on solenoid connectors to prevent corrosion
  
• Flush hydraulic fluid annually to remove varnish and moisture
  
• Exercise valve stems manually during service intervals
  
• Monitor diagnostic codes and address them before symptoms escalate
  

Operators who rarely use auxiliary attachments should still engage the system periodically to keep components moving and prevent internal sticking. This is especially important in humid climates or machines stored outdoors.
Final Thoughts
The Bobcat T250 remains a powerful and versatile loader, but its auxiliary hydraulic system demands attention—especially when attachments are used infrequently. A stuck solenoid or valve stem can lead to confusing behavior, including unintended movement and persistent diagnostic codes. With a combination of mechanical inspection, electrical awareness, and proactive maintenance, operators can restore full functionality and avoid downtime. In compact equipment, hydraulic precision is everything—and even a single sticky valve can throw the whole system off balance.