A method for controlling antennas in a vehicle having an external antenna and an internal antenna (221, 223, 320), the external antenna comprising an external mobile communication antenna (203, 311) and an external GPS antenna and the internal antenna comprising an internal mobile communication antenna and an internal GPS antenna, the external and internal mobile communication antennas connected through a first switch with a mobile communication module, the external and internal GPS antennas connected through a second switch with a GPS module and the first and second switches (330, 340) being controlled by a controller executing a mobile communication antenna diagnosis algorithm and a GPS antenna diagnosis algorithm, the method comprising: the controller executing the mobile communication antenna diagnosis algorithm by 1.1 triggering an eCall service function upon sensing an accident occurrence event; 1.2 measuring a quality of a wireless signal received through the external mobile communication antenna of the external antenna; and 1.3 switching the first switch from the external mobile communication antenna to the internal mobile communication antenna and performing the eCall service through the internal mobile communication antenna of the internal antenna when the measured quality of the wireless signal is less than a reference quality value; and the controller executing the GPS antenna diagnosis algorithm by 2.1 judging whether or not normal acquisition of position information through the external GPS antenna (201, 313) of the external antenna (200, 310) is possible; and 2.2 switching the second switch from the external GPS antenna to the internal GPS antenna and acquiring a current position information through the internal GPS antenna of the internal antenna when the normal acquisition of the position information through the external GPS antenna of the external antenna is unavailable. the controller executing the mobile communication antenna diagnosis algorithm by 1.1 triggering an eCall service function upon sensing an accident occurrence event; 1.2 measuring a quality of a wireless signal received through the external mobile communication antenna of the external antenna; and 1.3 switching the first switch from the external mobile communication antenna to the internal mobile communication antenna and performing the eCall service through the internal mobile communication antenna of the internal antenna when the measured quality of the wireless signal is less than a reference quality value; and 1.1 triggering an eCall service function upon sensing an accident occurrence event; 1.2 measuring a quality of a wireless signal received through the external mobile communication antenna of the external antenna; and 1.3 switching the first switch from the external mobile communication antenna to the internal mobile communication antenna and performing the eCall service through the internal mobile communication antenna of the internal antenna when the measured quality of the wireless signal is less than a reference quality value; and the controller executing the GPS antenna diagnosis algorithm by 2.1 judging whether or not normal acquisition of position information through the external GPS antenna (201, 313) of the external antenna (200, 310) is possible; and 2.2 switching the second switch from the external GPS antenna to the internal GPS antenna and acquiring a current position information through the internal GPS antenna of the internal antenna when the normal acquisition of the position information through the external GPS antenna of the external antenna is unavailable. 2.1 judging whether or not normal acquisition of position information through the external GPS antenna (201, 313) of the external antenna (200, 310) is possible; and 2.2 switching the second switch from the external GPS antenna to the internal GPS antenna and acquiring a current position information through the internal GPS antenna of the internal antenna when the normal acquisition of the position information through the external GPS antenna of the external antenna is unavailable.