Abstract: A backup proximity sensor for a vehicle includes a first passive infrared sensor (PIR) and a second PIR vertically mounted with respect to one another on a pivotal support member. The first PIR and second PIR are angularly directed such that the respective fields of view converge, establishing a detection zone in a region behind a vehicle. A drive motor and scanning gear box are coupled to the pivotal support member and pivotally drive the first and second PIR in an oscillatory fashion about a predetermined arc. This establishes relative motion between the PIRs and a stationary warm body in the field of view of the two sensors, allowing the stationary body to be detected. A detection circuit receives output signals from the first PIR and second PIR and generates an output signal indicative of a warm body being detected by both the first and second PIRs. This eliminates false alarms generated by warm bodies outside the region of the desired detection zone.