Troubleshooting Lift Pedal Lockup on the 2004 Bobcat S175

[MikePhua]

The Bobcat S175 and Its Place in Compact Equipment History
The Bobcat S175 skid steer loader was introduced in the early 2000s as part of Bobcat’s S-series, which revolutionized compact equipment with improved hydraulic performance, operator comfort, and electronic control systems. Bobcat, founded in 1947 in North Dakota, became synonymous with skid steers after launching the first compact loader in 1958. By the time the S175 hit the market, Bobcat had already sold hundreds of thousands of machines globally.
The S175 featured a 46-horsepower Kubota diesel engine, a rated operating capacity of 1,750 lbs, and a vertical lift path ideal for loading trucks and handling pallets. Its Advanced Control System (ACS) allowed operators to choose between hand and foot controls, and its integrated safety features—like the seat bar interlock and spool lock solenoids—were designed to prevent unintended movement.
Symptoms of a Locked Lift Pedal
A common issue reported in aging S175 units is the lift pedal becoming completely immobile, even when the safety bar is down and the system is activated. In contrast, the tilt pedal may still function, albeit inconsistently or for only a few seconds. This discrepancy often confuses operators and points to a deeper issue within the hydraulic control system.
Typical symptoms include:

• Left pedal (lift) remains locked regardless of safety bar position
  
• Right pedal (tilt) moves slightly even when it should be locked
  
• No fault codes appear on the display
  
• Green valve light illuminates correctly
  
• No audible alarm beeps indicating active faults
  

Terminology Clarification

• Spool Valve: A hydraulic component that directs fluid flow to actuate lift or tilt cylinders.
  
• Spool Lock Solenoid: An electrically controlled valve that locks the spool in place to prevent movement when the machine is not in operation.
  
• ACS (Advanced Control System): Bobcat’s electronic control interface that manages joystick and pedal inputs.
  
• Seat Bar Interlock: A mechanical safety feature that must be engaged for hydraulic functions to activate.
  

Root Cause Analysis and Diagnostic Strategy
The most probable cause of a locked lift pedal in the S175 is a failed spool lock solenoid. These solenoids are mounted on the hydraulic valve block and are responsible for locking or unlocking the lift and tilt spools. If the solenoid fails or becomes jammed, it prevents the pedal from moving, even though the rest of the system appears functional.
Diagnostic steps include:

• Verify whether the machine emits three short beeps when attempting to activate hydraulics. If not, no fault codes will be stored.
  
• Remove the spool lock solenoid from the lift spool and test pedal movement manually. This can be done with the engine off.
  
• Inspect the solenoid for debris, corrosion, or mechanical damage.
  
• Check the centering spring cap and float detent mechanism for internal obstructions.
  
• Confirm that the loader arms are fully lowered and the attachment is resting on the ground before disassembly.
  

In one case, a technician replaced the lift solenoid but didn’t test pedal movement before reassembly. Upon revisiting the issue, they found the new solenoid was functional, but debris inside the spool housing was preventing movement. Cleaning the internal components resolved the issue without further parts replacement.
Why the Tilt Pedal Still Moves
The tilt pedal’s partial movement, even when the safety bar is up, suggests that its corresponding spool lock solenoid may also be compromised—either physically broken or stuck in an unlocked position. While this might seem helpful, it actually poses a safety risk. Bobcat’s design ensures that both pedals should lock when the safety bar is raised. Any deviation from this behavior indicates a fault in the interlock system.
Recommendations:

• Replace both spool lock solenoids if one has failed, as they are wired together and often age similarly.
  
• Inspect wiring harnesses for frayed insulation or poor connections.
  
• Use dielectric grease on solenoid connectors to prevent moisture intrusion.
  
• Test pedal movement with solenoids removed to isolate mechanical from electrical faults.
  

Field Anecdotes and Operator Wisdom
A landscaping crew in Maryland reported that their S175’s lift pedal had been locked for weeks, forcing them to use only the tilt function for minor tasks. After replacing the solenoid and cleaning the spool housing, they regained full lift control. Interestingly, they noted that the tilt pedal had always been “a little loose,” suggesting the solenoid had been failing gradually.
In another case, a rental fleet manager in Tennessee discovered that several S-series machines had intermittent pedal lock issues due to corrosion in the seat bar switch. Replacing the switch and cleaning the contacts restored normal operation across the fleet.
Preventive Maintenance and Long-Term Solutions
To avoid pedal lock issues in the Bobcat S175:

• Replace spool lock solenoids every 2,000 hours or during major hydraulic service
  
• Keep loader arms down and attachments grounded during maintenance
  
• Clean and inspect seat bar interlock switches quarterly
  
• Use OEM solenoids and avoid aftermarket parts with inconsistent tolerances
  
• Train operators to recognize early signs of pedal resistance or inconsistent unlocking
  

For machines operating in wet or dusty environments, consider installing protective boots over pedal linkages and solenoid connectors. This simple upgrade can extend component life and reduce downtime.
Conclusion
Lift pedal lockup in the Bobcat S175 is typically caused by a failed spool lock solenoid or internal debris within the hydraulic valve. While the issue may seem electrical at first glance, mechanical inspection often reveals the true culprit. By understanding the interaction between safety interlocks, solenoids, and spool valves, operators and technicians can restore full functionality and keep these compact workhorses running reliably for years to come.