2010 Cadillac STS Owner's Manual - Page 143

When the System Does Not Seem to Work Properly If the URPA system will not activate due to a temporary condition a red light will be shown on the rear URPA display when the shift lever is moved into R (Reverse). This occurs under the following conditions: . . A trailer was attached to the vehicle, or a bicycle or an object was hanging out of the trunk during the last drive cycle, the red light may illuminate in the rear display. Once the attached 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 ultrasonic sensors are not clean. Keep your rear bumper free of mud, dirt, snow, ice and slush. For cleaning instructions, see Washing Your Vehicle on page 6‑111. The ultrasonic sensors are not clean. Keep the vehicle's rear bumper free of mud, dirt, snow, ice and slush. For cleaning instructions, see Washing Your Vehicle on page 6‑111. . . If the system is still disabled, after driving forward at least 15 mph (25 km/h), take the vehicle to your dealer/retailer. 3-43