An ultrasonic obstacle detection system that provides drivers with increased awareness when driving in reverse. The system sends out ultrasonic waves eight times per second, detecting obstacles within a 150-degree horizontal field behind the vehicle. A signal-processing algorithm in the microprocessor filters erroneous signals, reducing false signals. The system consists of a rugged, weather-resistant sensor mounted to the rear of the vehicle and a control unit that is spliced into the vehicle’s back-up lamp wiring.