2010 Buick LaCrosse Owner's Manual - Page 260

8-40 Driving and Operating Object Detection Systems Ultrasonic Parking Assist For vehicles with the Ultrasonic Rear Parking Assist (URPA) system, it assists the driver with parking and avoiding objects while in R (Reverse). URPA operates at speeds less than 8 km/h (5 mph), and the sensors on the rear bumper detect objects up to 2.5 m (8 ft.) behind the vehicle, and at least 20 cm (8 in.) off the ground. { WARNING The Ultrasonic Rear Parking Assist (URPA) system does not replace driver vision. It cannot detect: . How the System Works URPA comes on automatically when the shift lever is moved into R (Reverse). A single tone sounds to indicate the system is working. URPA operates only at speeds less than 8 km/h (5 mph). An obstacle is indicated by audible beeps. The interval between the beeps becomes shorter as the vehicle gets closer to the obstacle. When the distance is less than 30 cm (12 in.) the beeps are continuous. To be detected, objects must be at least 20 cm (8 in.) off the ground and below trunk level. Objects must also be within 2.5 m (8 ft.) from the rear bumper. The distance objects can be detected may be less during warmer or humid weather. PARK ASSIST OFF displays on the Driver Information Center (DIC) to indicate that URPA is off. The message disappears after a short period of time. Objects that are below the bumper, underneath the vehicle, or if they are too close or far from the vehicle Children, pedestrians, bicyclists, or pets. . If you do not use proper care before and while backing; vehicle damage, injury, or death could occur. Even with URPA, always check behind the vehicle before backing up. While backing, be sure to look for objects and check the vehicle's mirrors.