2008 Chevrolet Silverado 1500 Pickup Owner's Manual - Page 160

To be detected, objects must be at least 10 inches (25.4 cm) off the ground and below tailgate level. Objects must also be within 8 feet (2.5 m) from the rear bumper. This distance may be less during warmer or humid weather. A single beep will sound the first time an object is detected between 20 inches (0.5 m) and 8 feet (2.5 m) away. Beeping will occur for a short time when the vehicle is closer than 1 foot (0.3 m) from the object. The following describes what will occur with the URPA display as the vehicle gets closer to a detected object: Description amber light amber/amber lights amber/amber/red lights amber/amber/red lights flashing and beep for three seconds English 8 ft 40 in 23 in 1 ft Metric 2.5 m 1.0 m 0.6 m 0.3 m The system can be disabled by pressing the rear park aid disable button located next to the radio. The indicator light will come on and PARKING ASSIST OFF displays on the Driver Information Center (DIC) to indicate that URPA is off, see DIC Warnings and Messages on page 3-66 for information about clearing the message. Notice: If you use URPA while the tailgate is lowered, it may not detect an object behind your vehicle, and you might back into the object and damage your vehicle. Always verify the tailgate is closed when using URPA or turn off URPA when driving with the tailgate lowered. 2-66