Support personnel such as Dealer mechanics and Technicians may not have the necessary skill set to diagnose vehicle level CAN issues, especially when there are multiple buses, and upwards of 40 modules per vehicle. CAN issues may occur only once in a while, not allowing one to remember what they did last time to fix the issue. Many tools are available such as Service Manual, CAN Tool, Diagnostic Tools, CAN message list, and Diagnostic Specification, to make matters even more complicated. How can a new Mechanic or Technician be asked to troubleshoot such a complicated networked vehicle? Where should one begin? Training can help, but network communication is black magic to most. In an effort to quickly and accurately solve all vehicle level CAN issues, a Network Diagnostic Flow Chart, NDFC, for Nissan and Infinity vehicles was created. The NDFC reduces labor, summarizes experience, and if followed, will help solve all vehicle level CAN issues. The NDFC is a troubleshooting flow chart, similar to one you would find for any module but dedicated to the CAN network. The NDFC can and has diagnosed any vehicle level CAN and Diag-On-CAN diagnostic issues. All failure modes including but not limited to U1000's, configuration, CAN wiring issues, termination resistance, open grounds, and Gateway issues are covered. A concise, easy to follow flow chart will help the inexperienced and experienced troubleshoot CAN networks.