2003 Buick Rendezvous Owner's Manual - Page 174

How the System Works Unless disabled, the URPA will turn on automatically when the shift lever is moved into REVERSE (R). When the system turns on, the three lights on the display will illuminate for one anda half seconds to let you know that the system is working. If your vehicle is moving in REVERSE (R) at a speed greater than 3 mph (5 km/h), the red light will flash to remind you that the system does not work at speed greater than 3 mph (5 km/h). When the System Does Not Seem to Work Properly The light may flash red when the vehicle is in REVERSE (R) if the ultrasonic sensors are not kept clean. So be sure to keep your rear bumper free of mud, dirt, snow, ice and slush. Other conditions that may affect system performance include things like the vibrations from a jackhammer or the compression of air brakes on a very large truck. If after cleaning the rear bumper and then driving forward at least 15 mph (25 km/h), the display continues to flash red, see your dealer. If an object is detected at a REVERSE (R) speed of less than 3 mph (5 km/h), one of the following will occur: continuous chime If a trailer was attached to your vehicle, or a bicycle or an object was on the back of, or hanging out of your liftgate during your last drive cycle, the light may also flash red. The light will continue to flash whenever in REVERSE (R) until your vehicle is driven forward at least 15 mph (25 km/h) without any obstructions behind the vehicle. I I I chime i I 1 I For cleaning instructions, see Cleaning the Outside of YL)I-!T Vehicle nn pace 5-90. A chime will sound the first time an object is detected between 20 inches (0.5 m) and 5 feet (1.5 m) away. URPA cannot detect objects that are above liftgate level. In order for the rear sensors to recognize an object, it must be within detection range behind the vehicle. 3-23