A diagnostic tool that can communicate with a computing device such as smart phone is provided. The diagnostic tool can include a power management system that allows the dynastic tool to enter lower power state in order to prevent the power drain of vehicle battery. The diagnostic tool can also AutoID a vehicle or use a “fingerprinting” process to identify the vehicle. A crediting system is provided that can be used to credit a 3rd party for software purchased for use by the diagnostic tool or smart phone.