Why the Bobcat 337 Track Speed Won’t Switch

[MikePhua]

The Bobcat 337 Compact Excavator
The Bobcat 337 is a mid-sized compact excavator introduced in the early 2000s by Bobcat Company, a brand long associated with durable, operator-friendly machines for construction, landscaping, and utility work. Bobcat, originally founded in 1947 in North Dakota, became a global leader in compact equipment by the 1990s. The 337 model featured a 33-horsepower diesel engine, zero tail swing, and selectable track speed—allowing operators to switch between high and low travel modes depending on terrain and task.
Sales of the 337 were strong across North America, particularly among small contractors and rental fleets. Its compact footprint and hydraulic versatility made it ideal for trenching, grading, and demolition in confined spaces. However, like many machines of its era, the 337 relied on analog electrical systems that can become problematic with age.
Symptoms of Track Speed Failure
Operators have reported a failure in the high/low track speed switch. Initially, the machine remained in high speed until shut down. Upon restart, it defaulted to low speed and refused to switch back. The indicator light failed to illuminate, and the “Switch Control” fuse blew immediately upon startup.
This behavior suggests an electrical fault in the control circuit responsible for energizing the solenoid valve that shifts hydraulic flow between speed modes.
Terminology annotation:

• Track Speed Selector: A switch that toggles between high and low travel speeds by redirecting hydraulic flow.
  
• Solenoid Valve: An electrically actuated valve that controls fluid direction or pressure.
  
• Fuse: A protective device that interrupts electrical flow when current exceeds safe limits.
  
• Relay: An electrically operated switch used to control high-current circuits with low-current signals.
  

Tracing the Electrical Fault
The immediate fuse failure points to a short circuit—most likely a positive wire contacting ground. This could occur due to:

• Chafed wiring harnesses near the switch or solenoid
  
• Moisture intrusion causing corrosion and bridging
  
• Internal failure of the solenoid coil, creating a direct path to ground
  

To diagnose:

• Inspect all wiring from the switch to the solenoid for abrasion or pinching
  
• Use a multimeter to check continuity and resistance across the solenoid terminals
  
• Disconnect the solenoid and observe whether the fuse still blows
  
• Swap relays with known-good units to rule out internal relay shorts
  

In one case from Ontario, a contractor discovered that a wire had rubbed against the frame near the operator’s footwell, exposing copper and grounding the circuit. After repairing the insulation and rerouting the harness, the fuse held and the switch resumed normal function.
Solenoid Valve Integrity and Replacement
The solenoid controlling track speed is typically mounted near the hydraulic valve block. If it is internally shorted, it will draw excessive current and blow the fuse. Solenoids can be tested by:

• Measuring coil resistance (should be between 10–40 ohms depending on model)
  
• Applying 12V directly and listening for actuation
  
• Checking for continuity between coil terminals and valve body (should be infinite)
  

If the solenoid fails any of these tests, replacement is recommended. Use OEM parts or verified aftermarket equivalents with matching voltage and thread specifications.
Relay Behavior and Misinterpretation
Some operators attempt to “move relays” to troubleshoot. This can mean swapping, tapping, or reseating. While tapping may temporarily restore contact in a corroded relay, it’s not a reliable fix. Relays should be tested using a relay tester or replaced outright if suspected.
Ensure the relay socket is clean and free of oxidation. Apply dielectric grease to prevent future corrosion.
Aftermarket Switch Options
For older Bobcat models like the 331X or early 337s, OEM switches may be discontinued. Operators have successfully retrofitted waterproof momentary switches, such as Otto P9 or generic 12mm marine-grade toggles. These can be wired into the existing harness with proper sealing and strain relief.
When retrofitting:

• Confirm switch voltage and current rating
  
• Use heat-shrink tubing and sealed connectors
  
• Mount the switch in a protected location to avoid accidental activation
  

Preventative Measures and Long-Term Reliability
To prevent recurrence of track speed issues:

• Inspect wiring harnesses annually, especially near moving components
  
• Replace fuses with correct amperage ratings—typically 10A or 15A for control circuits
  
• Clean and reseal electrical connectors during seasonal maintenance
  
• Keep the operator’s footwell dry and free of debris that could damage wiring
  

In high-humidity regions, consider adding a small desiccant pack inside the control panel to absorb moisture.
Conclusion
The Bobcat 337’s track speed switching failure is typically caused by electrical shorts, solenoid faults, or relay degradation. With systematic diagnostics and attention to wiring integrity, the issue can be resolved without major component replacement. As these machines age, proactive electrical maintenance becomes essential—not just for performance, but for safety and uptime. The 337 remains a capable excavator, and with a few targeted repairs, it can continue serving reliably for years to come.