Embodiments of the present invention relate to a wireless appliance for monitoring a vehicle. In an embodiment, the appliance includes: (1) a microprocessor; (2) a vehicle-communication circuit; (3) a GPS module; and (4) a wireless transmitter. The wireless transmitter receives and transmits location-based data generated by the GPS module and diagnostic data collected by the vehicle-communication circuit. The vehicle-communication circuit is integrated into a single ASIC that includes modules for managing different vehicle-communication protocols, such as, for example, J1850 PWM, J1850 VPWM, ISO 9141-2, CAN, Keyword 2000, and J170S.