Disclosed are a method for recognizing whether an Adaptive Cruise Control (ACC) system operates abnormally based on information on a turn-on state of a brake lamp of a preceding vehicle, and a vehicle terminal therefor. One or more of a vehicle, a vehicle terminal, and an autonomous vehicle disclosed in the present invention may work in conjunction with Artificial Intelligence (AI), Unmanned Aerial Vehicle (UAV), a robot, an Augmented Reality (AR) device, a Virtual Reality (VR) device, a 5G service related device, etc.