Abstract: A backup aid system, for a vehicle, senses when the vehicle is in reverse gear. Ultrasonic sensors at the rear of the vehicle provide continuous range information to a control module for objects that are detected as being relatively close to the vehicle. A radar system provides range information to the control module for objects detected beyond the range of the ultrasonic system. At low speeds below a predetermined minimum speed level or when the system is placed in the "park" mode for parking, the radar information is ignored and only the ultrasonic information is used to warn the vehicle operator. At a relatively high threshold backup speed, the vehicle operator is immediately warned to slow down, whether or not an object is detected in the vehicle path. Between the lower and upper threshold speeds, both the ultrasonic system and the radar system are used to continuously range and detect any objects that enter their respective detection fields.