Check Engine Light on John Deere 110

[MikePhua]

The John Deere 110 series tractors, introduced in the early 1980s as part of Deere’s compact utility line, were designed for small farms and landscaping applications. Despite their reliability, a persistent issue that owners sometimes encounter is the illumination of the check engine light (CEL), signaling a problem with the engine or electronic monitoring systems.

Understanding the John Deere 110 Engine System
The JD 110 was typically equipped with a liquid-cooled gasoline engine, though some later variants included diesel models. The tractor features a basic electronic engine monitoring system, which connects to sensors that measure oil pressure, temperature, and ignition conditions. The CEL is triggered when one or more readings fall outside acceptable ranges.
Key components include:

• Oil Pressure Sensor: Monitors lubrication system; triggers warning if pressure drops below ~12 psi.
  
• Coolant Temperature Sensor: Activates warning if engine temperature exceeds 220°F (104°C).
  
• Ignition Coil & Module: Provides spark; faults here can simulate a CEL.
  
• Throttle Position & Governor Linkage: Irregular fuel input can mimic engine faults.
  

Common Causes for Check Engine Light Activation
Owners and technicians have observed several recurring reasons for CEL activation on JD 110 tractors:

• Low Oil Pressure: Often due to dirty oil, worn pump, or leaks.
  
• Electrical Connection Issues: Corrosion at sensor terminals or loose wires.
  
• Faulty Sensors: Oil pressure or temperature sensors that fail intermittently.
  
• Fuel Delivery Problems: Air in fuel lines, clogged filters, or weak pump.
  
• Ignition Malfunctions: Worn spark plugs, bad coil, or aging ignition module.
  

Troubleshooting Steps

1. Check Fluids: Ensure oil and coolant levels are within specifications.
   
2. Inspect Electrical Connections: Clean and tighten all sensor wiring and terminals.
   
3. Test Sensors: Use a multimeter to verify resistance and output against manufacturer specs.
   
4. Fuel System Examination: Look for leaks, air in lines, or clogged filters.
   
5. Ignition Check: Examine spark plugs, wires, coil, and module for wear or damage.
   
6. Monitor Engine Behavior: Run the tractor under load and note if CEL triggers at specific RPMs or temperatures.
   

Tips and Best Practices

• Maintain regular oil changes (every 50–100 hours for gasoline engines) to prevent low-pressure triggers.
  
• Keep sensor connections clean and apply dielectric grease to prevent corrosion.
  
• Document occurrences of CEL, noting engine load and temperature — patterns help diagnose intermittent issues.
  
• Consider replacement of aging sensors even if readings appear normal, as old sensors often fail under load.
  

Technical Terms Explained

• Check Engine Light (CEL): Indicator for engine-related issues monitored by sensors.
  
• Governor Linkage: Mechanical system controlling engine speed; improper adjustment can affect fuel delivery.
  
• Dielectric Grease: Non-conductive grease used to protect electrical connections from moisture and corrosion.
  

Conclusion
A check engine light on the John Deere 110 does not always indicate catastrophic failure, but it signals that a monitored parameter is out of specification. Most cases involve oil pressure, coolant temperature, or electrical sensor issues. Following a systematic inspection of fluids, electrical connections, sensors, and fuel/ignition systems can identify and resolve the problem. Proper preventive maintenance, including fluid replacement and electrical care, can significantly reduce the likelihood of CEL activation and keep the JD 110 running reliably for decades.