Bobcat 864 Lift Arm Stuck Up: Diagnosing a One-Way Hydraulic Issue

[MikePhua]

Overview of the Problem
The Bobcat 864, a rubber-tracked skid steer loader with a reputation for strength and versatility, has encountered a frustrating hydraulic malfunction: the lift arms raise properly but refuse to lower. This condition renders the machine nearly inoperable for digging, grading, or bucket-related work. Although the problem seems mechanical at first glance, its origins are deeply rooted in the machine’s electro-hydraulic system—specifically in valve control, safety interlocks, and pressure regulation.
Understanding the Hydraulic Circuitry
Bobcat 864 machines are equipped with an electro-hydraulic spool valve system. The main valve block distributes flow to the tilt and lift cylinders based on joystick inputs. Each function—lift up, lift down, tilt back, tilt forward—has dedicated valve spools operated by solenoids. These solenoids respond to signals from the hand controls and must be properly energized to open their respective valves.
A lift arm that only moves in one direction, especially upward but not downward, generally indicates one of the following:

• A failed or stuck solenoid controlling the "lower" function
  
• A blocked return path or hydraulic restriction
  
• A safety interlock system (such as the seat bar or control panel) not completing the circuit
  
• A broken wire, short, or faulty signal from the joystick control system
  
• Mechanical binding in the valve spool or internal cylinder damage
  

First Signs and Diagnostic Attempts
Operators reported that the arms would raise fine but would not lower, regardless of whether the machine was running or in key-on, engine-off mode. Even pressing the override button yielded no movement. One key sign: when activating the lower function, there was no sound or hydraulic reaction—not even a relief valve hiss or attempt to build pressure. This immediately indicated that the solenoid for lowering was not engaging at all.
This behavior points to either a failed solenoid or a complete loss of electrical signal to the valve. It’s important to note that Bobcat’s system uses a specific ground-switching logic: the controller supplies voltage constantly, and the joystick completes the ground when an action is selected. A failed ground or broken wire can prevent activation.
Electrical Troubleshooting: Solenoid and Signal Testing
Operators and technicians began by swapping the “lift up” and “lift down” solenoids. After the swap, the “up” function stopped working and the “down” function worked—proving the solenoid itself was not the problem. Instead, the issue lay in the electrical signal being sent to that solenoid.
The following steps were taken:

• Confirmed power was present at the valve block harness
  
• Verified continuity of ground path during joystick actuation
  
• Checked for shorts or broken wires from joystick to the valve harness
  
• Inspected the controller under the seat for corrosion, damaged pins, or loose connectors
  

One recurring cause in many machines: frayed or pinched wires around the seat hinge or under the cab where they pass close to hydraulic fittings. Over time, vibrations and oil seepage can cause wire jackets to degrade or chafe through.
Bypass Attempts and Manual Lowering
With the lift arms stuck in the raised position, many operators face the challenge of how to lower them safely for repairs. Bobcat provides a manual override procedure using the BICS (Bobcat Interlock Control System) button and key-on engine-off conditions, but that only works if the solenoid circuit is functional.
In emergencies, hydraulic line ports can be cracked slightly to relieve pressure and allow gravity to lower the arms. This is dangerous and should only be performed with adequate support and safety blocks in place.
Valve Spool Mechanical Issues
In rare cases, a spool valve can become mechanically stuck due to contamination, rust, or internal scoring. If the electrical circuit checks out, and the solenoid is activating but nothing moves, it may be necessary to remove the valve block and inspect for physical obstructions or broken detent springs. Small metal shavings or O-ring debris can seize a spool in place.
Seat Bar and Safety Switch Malfunctions
The Bobcat 864 integrates several operator-presence switches including:

• Seat bar down switch
  
• Operator in seat sensor
  
• BICS override switch
  

If any of these are malfunctioning or not registering correctly, the system may lock out lift and tilt functions for safety. A faulty seat bar switch, for example, could allow the arms to raise but prevent them from lowering if the system interprets the operator as "not present." Cleaning contacts and testing continuity across these switches can eliminate these as potential causes.
Lessons from the Field
A mechanic once worked on a similar case involving a 763 where the arms would go up but not down. It turned out that mice had chewed through just one signal wire under the seat bar—barely visible. A small splice and re-insulation fixed the problem entirely.
Another operator shared an experience with a Case skid steer showing identical symptoms. In that case, it was a corroded pin on the joystick controller connector that was losing continuity under load. These examples show the importance of detailed electrical diagnostics and not rushing to replace hydraulic components prematurely.
Checklist for One-Way Hydraulic Operation
A practical checklist for troubleshooting this issue includes:

• Swap solenoids for the “up” and “down” functions
  
• Verify power and ground are present at the valve block harness
  
• Test continuity from joystick control to valve harness
  
• Check seat bar switch and seat sensor inputs
  
• Inspect connector terminals for corrosion or loose pins
  
• Trace wires for chafing or breakage, especially near the seat and undercarriage
  
• Test BICS override function
  
• Manually actuate valve spools (if safely accessible) to test for mechanical binding
  
• Review controller fault codes (if available)
  

Conclusion
The Bobcat 864 lift arm "won’t go down" issue is a classic case of intermittent or failed electrical actuation in a hydraulically sound machine. By focusing on logical diagnostic steps—starting with the simplest (solenoid swaps) and progressing to wiring and controller inputs—most operators can isolate the fault without costly part replacements. In nearly every case, patience and a multimeter are more valuable than guesswork and new valves.