Resetting the Alternator Battery Warning Light on the John Deere 85D

[MikePhua]

The John Deere 85D is a powerful, compact excavator commonly used in construction and landscaping. It is equipped with a robust electrical system that includes a battery and alternator, both of which are crucial for ensuring the machine runs smoothly. However, operators may occasionally encounter an issue where the alternator or battery warning light remains illuminated on the dashboard, even after the issue has been resolved. In this article, we’ll explore the potential causes of this problem, how to reset or clear the warning light, and offer advice on maintaining the alternator and battery system to avoid future issues.
Understanding the Alternator and Battery Warning Light
The alternator and battery warning light on a John Deere 85D serves as an indicator that there may be an issue with the electrical system. When the light comes on, it typically signals that the alternator is not charging the battery properly, or that the battery itself may be failing. These issues can lead to problems such as poor engine performance, difficulty starting the machine, or even complete electrical failure.
Common reasons for the alternator battery warning light to appear include:

1. Alternator Failure: The alternator is responsible for charging the battery while the engine is running. If it’s malfunctioning or worn out, it may not provide enough charge to the battery, triggering the warning light.
   
2. Loose or Corroded Battery Connections: A loose or corroded battery terminal can prevent the battery from being charged properly, causing the warning light to turn on.
   
3. Faulty Voltage Regulator: The voltage regulator controls the amount of power being sent to the battery from the alternator. If the regulator fails, it can lead to undercharging or overcharging, both of which may trigger the warning light.
   
4. Low Battery Charge: A battery that is near the end of its lifespan may not hold a charge properly, which can cause the alternator to work harder than it should.
   

How to Reset or Clear the Warning Light
If the alternator or battery issue has been resolved but the warning light remains on, you may need to reset or clear the light manually. Here’s how you can do it:

1. Check the Electrical System
   Before attempting to reset the warning light, ensure that there are no underlying issues with the alternator or battery. Inspect the battery terminals for corrosion, ensure that all connections are tight, and check the alternator for any visible signs of damage or wear.
   
2. Turn Off the Ignition
   Begin by turning off the ignition and allowing the machine to sit for a few minutes. This can help reset the electrical system and may clear the warning light automatically.
   
3. Perform a Battery Disconnect
   If the light does not turn off after a few minutes, try disconnecting the battery. Begin by turning off the ignition, then remove the negative battery terminal. Wait for about 10-15 minutes before reconnecting the battery. After reconnecting, turn the ignition back on and check if the warning light has cleared.
   
4. Use the Diagnostic Tool
   If the light is still illuminated, it may require a diagnostic scan. John Deere machines typically come with a built-in diagnostic port that allows technicians to connect a diagnostic tool and clear the warning light. This tool can help identify any underlying electrical issues and reset the warning light if the problem has been resolved.
   
5. Check for Fault Codes
   In some cases, the warning light may be linked to a specific fault code. By using the diagnostic tool, you can read and clear any fault codes that may be stored in the machine's computer. This step is particularly useful if the light does not go off after you’ve addressed any potential mechanical issues.
   

Preventing Future Alternator and Battery Issues
To avoid encountering the alternator or battery warning light in the future, it’s important to regularly maintain the electrical system of the John Deere 85D. Here are a few maintenance tips to keep the alternator and battery running smoothly:

1. Inspect Battery Terminals Regularly
   Clean the battery terminals and check for any signs of corrosion or loose connections. Corroded terminals can impede the flow of electricity and cause charging issues. Cleaning the terminals with a wire brush and applying a thin coat of petroleum jelly can help prevent corrosion.
   
2. Test the Alternator and Battery
   Periodically test the alternator and battery to ensure that they are functioning properly. A simple battery load test can determine whether the battery is holding a charge, while an alternator test can confirm that it is charging the battery correctly. If either component is showing signs of wear or poor performance, they should be replaced.
   
3. Check the Voltage Regulator
   The voltage regulator is a critical component in maintaining a stable electrical system. Have it checked periodically to ensure that it’s regulating the alternator’s output correctly. If it’s malfunctioning, it can lead to issues with both the alternator and battery.
   
4. Monitor Electrical Components
   Keep an eye on all electrical connections, including wires, fuses, and relays. Over time, these components can wear out or become damaged, causing issues with the electrical system. Regular inspections can help detect any problems early and prevent costly repairs down the road.
   
5. Keep the Battery Charged
   If the excavator is not used for extended periods, consider using a battery maintainer or trickle charger to keep the battery at optimal charge levels. This will prevent the battery from losing its charge and ensure it’s ready for use when needed.
   

John Deere: A Legacy of Innovation
John Deere, a global leader in agricultural and construction machinery, has been producing reliable equipment for over 180 years. Founded in 1837, the company initially gained fame for its durable plows and farm equipment. Today, John Deere’s lineup includes a wide range of machinery, from tractors to excavators like the 85D.
The John Deere 85D is part of the company’s mid-sized excavator series and is known for its powerful performance, fuel efficiency, and advanced technology. It is widely used in construction, roadwork, and landscaping projects, offering operators both comfort and productivity.
Conclusion
The alternator and battery warning light on the John Deere 85D can be a source of frustration for operators, but in most cases, it’s a problem that can be easily resolved. By performing basic checks, such as inspecting the battery and alternator, or using diagnostic tools, operators can clear the warning light and get back to work quickly. Regular maintenance, including checking connections, testing components, and monitoring the voltage regulator, will help ensure that the electrical system remains in good condition, reducing the likelihood of future issues.