There is a fault in the program on the auto cruise control unit, and therefore, during automatic braking is engaged by the ACC (Adaptive Cruise Control, which is a constant speed driving/inter-vehicular distance controlling device), either if the driver performs a braking operation or if the CMBS (collision mitigation brake system) engages, the cruise control program will not detect the end of these braking operations. As a result, the brake lights will keep illuminating until the vehicle stops.