2010 Buick LaCrosse Owner's Manual - Page 261

Driving and Operating Turning the System On and Off The URPA system can be turned on and off using the park assist button located next to the shift lever. 8-41 When the System Does Not Seem to Work Properly SERVICE PARK ASSIST: If this message occurs, take the vehicle to your dealer/retailer to repair the system. PARK ASSIST OFF: If the URPA system does not activate due to a temporary condition, the message displays on the DIC, see Driver Information Center (DIC) on page 4‑25 for more information. This can occur under the following conditions: . . An object was hanging out of the trunk during the last drive cycle. Once the object is removed, URPA will return to normal operation. The vehicle's bumper is damaged. Take the vehicle to your dealer/retailer to repair the system. Other conditions may affect system performance, such as vibrations from a jackhammer or the compression of air brakes on a very large truck. . . The park assist button lights up when the system is on and turns off when it has been disabled. URPA defaults to the on setting each time the vehicle is started. The driver has disabled the system. The ultrasonic sensors are not clean. Keep the vehicle's rear bumper free of mud, dirt, snow, ice and slush. For cleaning instructions, see Exterior Care on page 9‑84. . If the system is still disabled, after driving forward at least 40 km/h (25 mph), take the vehicle to your dealer/retailer.