Troubleshooting the Bell 850J Dozer: Error Code Left Coil Pump Open

[MikePhua]

The Bell 850J dozer is a heavy-duty piece of machinery widely used in construction, mining, and other earthmoving projects. Known for its rugged design and powerful performance, the 850J has become a trusted tool for operators around the world. However, like any complex machine, it can sometimes encounter errors that require troubleshooting to maintain optimal performance.
One common issue that operators might face is the "Left Coil Pump Open" error code, which can affect the functionality of the dozer’s hydraulic and transmission systems. In this article, we will explore the causes behind this error, how to troubleshoot it, and some practical steps to resolve the issue. We will also provide real-world insights on how proper maintenance and early diagnosis can keep your Bell 850J running smoothly.
Understanding the "Left Coil Pump Open" Error
The “Left Coil Pump Open” error typically points to an issue with the hydraulic system, specifically the left hydraulic pump coil. This error usually indicates that there is an electrical or hydraulic fault, which may involve issues such as:

1. Open Circuit: This could be due to a malfunctioning sensor or wiring issue that prevents the signal from reaching the left coil pump. An open circuit disrupts the proper operation of the hydraulic pumps, potentially affecting the dozer's ability to perform tasks like moving earth or controlling the blade.
   
2. Faulty Wiring or Connector: A loose, corroded, or damaged wire can cause an open circuit, leading to the left coil pump not receiving the necessary electrical input. In some cases, corrosion from environmental exposure or wear and tear over time can damage the connectors.
   
3. Pump Coil Malfunction: The issue could also stem from a malfunction within the pump coil itself, which may need to be replaced if it’s faulty or damaged.
   
4. Electrical Control System Failure: Sometimes, the problem might not be within the pump itself but in the electrical control system. The failure of the control system could stop the pump from operating at full capacity or even from activating at all.
   

How to Troubleshoot the Left Coil Pump Open Error
When confronted with the Left Coil Pump Open error on the Bell 850J, the first step is to carry out a systematic troubleshooting approach. Below are some steps that can help diagnose and resolve the issue:

1. Check for Faulty Wiring:
   Begin by inspecting the wiring that connects the left coil pump to the dozer’s electrical system. Look for any signs of wear, corrosion, or frayed wires. A loose or disconnected wire could be the cause of the error. If damaged, the wires should be replaced or reconnected.
   
2. Inspect the Electrical Connectors:
   Inspect all the electrical connectors, especially those around the pump coil. Look for signs of corrosion or dirt, which could interfere with the electrical signal. Clean the connectors and ensure they are securely connected.
   
3. Test the Pump Coil:
   If the wiring and connectors appear to be in good condition, the next step is to check the pump coil itself. Use a multimeter to check for continuity across the pump coil. If the coil is faulty, it may need to be replaced.
   
4. Examine the Hydraulic System:
   The issue could also be related to a fault in the hydraulic system, such as low fluid levels, contamination, or air in the lines. Check the hydraulic fluid levels and ensure that the fluid is clean and at the proper viscosity. If needed, flush the hydraulic system and replace the fluid.
   
5. Check the Electrical Control System:
   If the previous steps don’t resolve the issue, the problem might lie within the dozer’s electrical control system. Run diagnostic tests to check for any errors in the control module or sensors. Consult the machine’s user manual or a professional technician for further guidance.
   

Resolving the Left Coil Pump Open Error
Once you’ve pinpointed the issue, the next step is to resolve it. Here are some solutions based on common causes:

1. Repair or Replace Wiring and Connectors:
   If you find faulty wiring or connectors, repair or replace them as necessary. Ensure that the wiring is properly insulated and that connectors are corrosion-free and securely connected.
   
2. Replace the Pump Coil:
   If the pump coil is found to be defective, replacing it is the most effective solution. Ensure that you use genuine parts to maintain the integrity of the hydraulic system and prevent future issues.
   
3. Clean or Replace Electrical Components:
   Clean the connectors and electrical components to remove any dirt, debris, or corrosion. If cleaning does not resolve the issue, consider replacing the faulty components, such as the control relay or sensors, which could be causing the error.
   
4. Flush the Hydraulic System:
   If the issue is related to contamination or low hydraulic fluid, flush the system and replace the fluid with the recommended type. Regularly maintaining the hydraulic system can prevent buildup and ensure smooth operation.
   

Preventative Maintenance Tips for the Bell 850J
Preventative maintenance is crucial to keeping your Bell 850J dozer in top condition and preventing errors like the Left Coil Pump Open from occurring. Below are some maintenance practices that can help extend the lifespan of the machine:

1. Regular Hydraulic Fluid Checks:
   Keep an eye on the hydraulic fluid levels and condition. Dirty or low hydraulic fluid can cause the system to malfunction, leading to costly repairs and downtime. Always use the recommended hydraulic fluid type for optimal performance.
   
2. Clean Electrical Connectors:
   Regularly clean the electrical connectors and ensure they are securely connected. Corrosion or dirt on the connectors can lead to issues with electrical signals, which may affect the functionality of the pumps and other components.
   
3. Inspect and Replace Worn Parts:
   Periodically inspect key components such as hydraulic pumps, hoses, filters, and seals. Replacing worn parts before they fail will help prevent more serious issues from arising, reducing the risk of costly repairs.
   
4. Monitor Error Codes:
   Pay attention to error codes that may appear on the dozer’s control panel. These codes provide valuable information on potential issues, allowing for early diagnosis and preventive action.
   
5. Consult the Manual:
   Regularly refer to the machine’s user manual for maintenance schedules, recommended fluids, and troubleshooting tips. The manual provides essential information that can help you identify issues early and take appropriate action.
   

Real-World Example: Bell 850J in Action
A construction company in Texas experienced a Left Coil Pump Open error on their Bell 850J while working on a large earthmoving project. The machine had been running smoothly for hours when suddenly it stopped functioning, displaying the error code on the dashboard.
The operators quickly stopped the machine and conducted an initial check. They found some corrosion on the hydraulic pump connectors, which was likely the cause of the error. After cleaning and reattaching the connectors, the machine ran smoothly again, saving the company from costly downtime and keeping the project on schedule.
Conclusion: Addressing the Left Coil Pump Open Error
The Left Coil Pump Open error on the Bell 850J dozer can be a challenging issue, but with systematic troubleshooting and a methodical approach, operators can resolve it efficiently. By regularly maintaining the machine’s hydraulic and electrical systems, operators can prevent such errors and ensure smooth operation.
Understanding how to diagnose and address common issues is key to extending the lifespan of the dozer and maximizing its productivity. By following proper maintenance practices and addressing errors promptly, you can ensure that your Bell 850J continues to perform at its best, keeping your projects on track and minimizing downtime.