A vehicle communication system that includes an antenna system for a vehicle and a method of determining a connectivity status of the antenna system. The antenna system includes a test antenna for transmitting a wireless diagnostic signal with a signature waveform and a primary antenna that receives the wireless diagnostic signal and provides a corresponding wired diagnostic signal to a diagnostic circuit. The diagnostic circuit is configured to determine a connectivity status of the antenna system based on the presence or absence of the signature waveform in the wired diagnostic signal received from the primary antenna. It is possible for the diagnostic circuit to include a finite state machine (FSM) for carrying out the connectivity status determination.