SR250 ATS Fail: Understanding, Diagnosing, and Fixing the Problem

[MikePhua]

The Bobcat SR250 skid steer loader is a popular machine in the heavy equipment industry, known for its power and versatility. However, like any complex piece of machinery, it can encounter issues that affect its performance. One of the common issues reported by operators is a failure in the ATS (Automatic Traction System), which can lead to the loader’s drive system malfunctioning. In this article, we will dive into what causes an SR250 ATS fail, how to diagnose the issue, and the steps to resolve it, helping you restore your machine’s optimal performance.
What is the ATS in the Bobcat SR250?
The ATS (Automatic Traction System) is an essential component in the Bobcat SR250’s drive system. It is designed to enhance the machine’s traction, especially in challenging terrain. When the system detects that one of the wheels is slipping or losing traction, it automatically adjusts the drive to the other wheels to maintain stability and prevent the loader from getting stuck.
This system relies on sensors, hydraulics, and the machine’s electronic control unit (ECU) to function smoothly. It automatically adjusts the power delivered to each wheel based on the traction needs, ensuring the loader operates efficiently even in difficult conditions.
Signs of an ATS Failure
Before diving into troubleshooting and fixing the ATS failure, it’s important to recognize the signs of a malfunction. Some common symptoms that indicate an issue with the ATS in the Bobcat SR250 include:

• Uneven or erratic movement: If the loader seems to be having trouble maintaining traction or operates unevenly, the ATS could be malfunctioning. You may notice the machine jerking or hesitating as it moves.
  
• Loss of power to one side: If one side of the loader seems weaker or is not receiving adequate power, it could indicate that the ATS is not properly distributing power to the wheels.
  
• Warning lights or error codes: The Bobcat SR250 is equipped with a display panel that will show error codes when there is a problem with the ATS. A check engine light or an ATS warning light is a direct indicator of system failure.
  
• Hydraulic pressure fluctuations: A failure in the ATS may lead to erratic hydraulic pressure or the inability to adjust traction as needed.
  

If you notice any of these symptoms, it’s time to investigate further and address the issue.
Common Causes of ATS Failures
Several factors can lead to an ATS failure in the Bobcat SR250. Below are some of the most common causes:

1. Faulty Sensors
   The ATS relies on sensors to detect wheel slippage and adjust traction accordingly. If the sensors malfunction or become clogged with dirt, mud, or debris, they may not send the correct signals to the system, causing the ATS to fail.
   • Solution: Inspect the sensors for any visible damage or debris buildup. Clean them thoroughly or replace them if necessary. It’s also a good idea to check the electrical connections to ensure they are secure and free of corrosion.
     
2. Hydraulic System Issues
   The ATS system depends on the hydraulic system to adjust the power distribution to the wheels. If there is a leak in the hydraulic lines, low fluid levels, or a failing hydraulic pump, it could cause the ATS to malfunction.
   • Solution: Check the hydraulic fluid levels and ensure they are within the recommended range. If the fluid is low or dirty, replace it. Inspect all hydraulic hoses and fittings for leaks and repair or replace any damaged components.
     
3. Electrical or Wiring Problems
   The ATS system is controlled by the Bobcat SR250’s electronic control unit (ECU), which receives input from the sensors and relays the information to the hydraulic system. If there is a problem with the wiring, connectors, or ECU, the ATS may fail to function.
   • Solution: Inspect the wiring and connectors leading to the ATS system. Look for signs of wear, corrosion, or loose connections. If the ECU is suspected to be faulty, you may need to have it tested or replaced.
     
4. Faulty Traction Control Valves
   The traction control valves play a crucial role in adjusting the power sent to each wheel. If these valves become clogged, damaged, or worn out, the ATS system may fail to adjust traction properly.
   • Solution: Inspect the traction control valves and clean or replace them if necessary. Regular maintenance of these components is essential to keeping the ATS functioning properly.
     
5. Software or Calibration Issues
   In some cases, the ATS may fail due to software glitches or calibration errors in the ECU. Over time, the ECU may need to be recalibrated to ensure that it’s correctly interpreting sensor signals and controlling the hydraulic system.
   • Solution: Perform a diagnostic check on the ECU to identify any software errors or calibration issues. Recalibrating the system or updating the software may resolve the issue.
     

Diagnosing the ATS Failure
Once you’ve identified the symptoms, the next step is to diagnose the ATS failure. Here’s a step-by-step process for diagnosing the issue:

1. Check the Display Panel for Error Codes
   The Bobcat SR250 features a display panel that shows error codes related to various systems, including the ATS. Use the diagnostic tool to read the error codes and identify the specific problem with the ATS. This will guide you in narrowing down the potential causes.
   
2. Inspect the Sensors
   Start by checking the sensors in the ATS system. Look for signs of dirt, damage, or malfunction. Clean or replace the sensors as needed and check the wiring for any loose connections.
   
3. Check Hydraulic Fluid and Pressure
   Inspect the hydraulic fluid levels and ensure there are no leaks in the system. If the fluid is low or contaminated, replace it with fresh fluid. Additionally, check for any issues with the hydraulic pump that could affect pressure distribution to the wheels.
   
4. Test the Electrical System
   Examine the wiring and electrical connections leading to the ATS system. Look for damaged or corroded connectors. If you suspect a wiring issue, use a multimeter to test for continuity and voltage at the sensors and ECU.
   
5. Test the Traction Control Valves
   The traction control valves should be tested for functionality. If they are clogged, they may not be able to regulate the hydraulic pressure properly. Clean or replace any malfunctioning valves.
   
6. Recalibrate the ECU
   If the ATS system still fails after checking the sensors, hydraulics, and electrical system, it may be necessary to recalibrate the ECU or update the software. This can usually be done using a diagnostic tool or by visiting an authorized Bobcat service center.
   

Preventive Maintenance to Avoid ATS Failures
To minimize the risk of an ATS failure in the future, it’s important to implement a regular maintenance schedule. Here are some key preventive maintenance tips:

1. Regular Sensor Inspections
   Regularly inspect the sensors in the ATS system to ensure they are free from dirt and debris. Cleaning the sensors periodically can help prevent false readings and ensure that the system functions properly.
   
2. Hydraulic System Maintenance
   Maintain proper hydraulic fluid levels and perform routine checks for leaks or contamination in the hydraulic lines. Replace fluid and seals as necessary to prevent system failures.
   
3. Check Electrical Connections
   Inspect the wiring and connectors for signs of wear, corrosion, or loose connections. Tighten or replace damaged connectors to ensure that the electrical system is working as intended.
   
4. Traction Control Valve Checks
   Inspect and clean the traction control valves regularly. This will help ensure smooth power distribution to the wheels, preventing ATS failures.
   
5. Routine ECU Diagnostics
   Perform routine diagnostics on the ECU to check for any software glitches or calibration issues. Keeping the ECU updated and properly calibrated will help prevent failures in the ATS system.
   

Conclusion
The ATS failure in the Bobcat SR250 can cause significant issues with the loader's traction and performance, but with careful diagnostics and maintenance, you can identify and fix the problem. Whether the issue is with the sensors, hydraulics, electrical system, or traction control valves, taking the time to troubleshoot and resolve the issue will help restore your machine's functionality. Regular maintenance and proactive care are essential to keeping the ATS system in good working condition and avoiding future failures.