Diagnosing and Replacing the Wiper Motor on a Bobcat S185

[MikePhua]

The Bobcat S185 and Its Electrical Systems
The Bobcat S185 skid steer loader, manufactured by Bobcat Company (a division of Doosan Group), was introduced in the early 2000s as part of the S-series lineup. With a rated operating capacity of 1,850 lbs and a 56 hp diesel engine, the S185 became one of the most popular compact loaders in North America and Europe. Its enclosed cab option included a basic electrical system for lighting, HVAC, and windshield wipers—features that added comfort and safety for operators working in harsh conditions.
The wiper system on the S185 is powered by a 12V DC motor mounted behind the front cab panel. It drives a single-arm wiper mechanism through a gear assembly, sweeping across the curved windshield to maintain visibility in rain, snow, or mud. While simple in design, the wiper motor is prone to failure if obstructed or overloaded.
Common Failure Scenario and Initial Symptoms
One of the most frequent issues occurs when the wiper arm becomes physically stuck—either due to ice buildup, mechanical damage, or a broken linkage. If the motor continues to run while the arm is jammed, it can overheat and burn out. In such cases, the motor may stop functioning entirely, even after the obstruction is cleared.
Operators often assume that cycling the machine’s power will reset the motor, but this rarely works if the internal windings have been damaged. A telltale sign of motor burnout is the absence of any sound or movement when the wiper switch is engaged, despite all fuses testing good.
Locating the Wiper Switch and Troubleshooting Access
The wiper switch on the S185 is notoriously awkward to reach—positioned over the operator’s left shoulder near the rear of the cab. This placement has been criticized for years, as it requires the operator to twist uncomfortably to activate or deactivate the wiper.
When diagnosing a non-functional wiper motor:

• Confirm that the switch is in the “on” position
  
• Check the fuse panel for blown fuses (typically 10A or 15A)
  
• Inspect wiring harnesses for corrosion or loose connectors
  
• Test voltage at the motor terminals using a multimeter
  
• Listen for motor hum or vibration when switch is engaged
  

If voltage is present but the motor does not respond, it is likely internally damaged and requires replacement.
Replacement Options and Cost Considerations
OEM wiper motor assemblies for the S185 can cost upwards of $200, depending on the dealer and region. These assemblies typically include the motor, gear housing, and mounting bracket. However, many operators have found success sourcing aftermarket or cross-compatible motors from agricultural equipment.
For example:

• Bosch wiper motors used in combines or tractors often share mounting patterns and gear ratios
  
• Sweep angle can be adjusted by repositioning a pin on the internal gear
  
• Motors with part numbers stamped on the housing can be matched online or through salvage yards
  

One operator sourced a used Bosch motor from a combine for under $50 and modified the gear sweep to match the S185’s windshield arc. This approach saved significant cost and restored full functionality.
Understanding Sweep Angle and Gear Adjustment
The sweep angle—the arc through which the wiper moves—is controlled by a pin or cam inside the gear housing. If the replacement motor has a different default sweep, it may cause the wiper to overshoot or undershoot the windshield. Adjusting the pin position allows fine-tuning of the motion.
Steps to adjust sweep angle:

• Remove gear cover from motor housing
  
• Locate sweep control pin or cam
  
• Reposition to desired angle (typically 90° to 120° for skid steers)
  
• Reassemble and test before final installation
  

This adjustment is critical when using motors from other equipment, as agricultural machines often have wider windshields and different sweep requirements.
Field Anecdotes and Practical Advice
A Wisconsin operator once broke his wiper arm during a snowstorm and left the motor running for several minutes before shutting down the machine. After repairing the arm, he found the motor completely dead. Rather than paying full dealer price, he sourced a compatible Bosch motor from a salvage yard and restored operation with minor modifications.
Another technician in Illinois noted that many Bobcat wiper motors share components with Massey Ferguson and New Holland tractors. By cross-referencing part numbers, he was able to stock replacements at half the cost of OEM units.
These stories highlight the value of resourcefulness and mechanical understanding when dealing with electrical failures in compact equipment.
Recommendations for Long-Term Reliability
To prevent wiper motor failure and extend system life:

• Always turn off the wiper switch before shutting down the machine
  
• Clear ice and debris from the wiper arm before operation
  
• Lubricate pivot points and linkage annually
  
• Inspect wiring for corrosion, especially in humid environments
  
• Consider installing a relay to reduce switch load and improve longevity
  

For machines operating in winter conditions, adding a wiper arm heater or using silicone blades can reduce ice buildup and prevent mechanical jams.
Conclusion
Wiper motor failure on the Bobcat S185 is often caused by mechanical obstruction and continuous load on the motor. While OEM replacements are available, savvy operators can source compatible motors from agricultural equipment and adjust sweep angles to match. With proper maintenance and a bit of ingenuity, the wiper system can be restored affordably—ensuring clear visibility and safe operation in all weather conditions.