📋 Case Study

Case Study: CAN Bus Resets on John Deere 8R Tractor with AutoTrac Retrofit

Intermittent VT resets and GPS position loss during high-humidity field operations

🏗️ Project Overview

Precision farming fleet upgrade across 120,000-acre Midwest corn operation

🎯 Challenge

Intermittent VT resets and GPS position loss during high-humidity field operations

🔧 Design Approach

Redesigned star-ground topology with isolated VT power supply, relocated main ground lug to frame crossmember near cab mounting point, added ferrite-clamped shield termination at ECU end only

📐 Design Diagram

_noise ≤ 2.4 mV_pp @ 24V (0.1×) High Humidity CAN Bus Ground Path Ferrite Clamp Challenge

AI-generated project design illustration

📐 Key Calculations

Ground Noise Budget

Vnoise = 0.1 × Vsupply

Result: 2.4 mVpp @ 24V

Threshold for stable VT communication

Bond Resistance Target

R ≤ 0.5 mΩ per SAE J1113-11

Result: 0.32 mΩ measured

Validated low-impedance path

📊 Results

99.98% uptime improvement; zero VT resets over 6-month validation period; 42% reduction in service calls related to electronics

💡 Lessons Learned

•ECU ground reference must be electrically closer to VT than battery negative
•Shield drain wire must terminate at single point — not both ends
•Humidity exacerbates poor ground integrity via surface leakage paths

✅ Key Takeaways

1ECU ground reference must be electrically closer to VT than battery negative
2Shield drain wire must terminate at single point — not both ends
3Humidity exacerbates poor ground integrity via surface leakage paths