2002 Cadillac Seville Owner's Manual - Page 172

If the URPA system is not functioning properly, the display will flash red, indicating that there is a problem. The light will also flash red while driving if a trailer is attached to your vehicle, or a bicycle or object is on the back of, or hanging out of your trunk. The light will continue to flash until the trailer or the object is removed and your vehicle is driven forward at least 15 mph (25 km/h). It may also flash red if the ultrasonic sensors are not kept clean. So be sure to keep your rear bumper free of mud, dirt, snow, ice and slush or materials such as paint or the system may not work properly. If after cleaning the rear bumper and driving forward at least 15 mph (25 km/h), the display continues to flash red, see your dealer. For cleaning instructions, see "Cleaning, Outside of Your Vehicle" in the Index. It may also flash red if your vehicle is moving in REVERSE (R) at a speed greater than 3 mph (5 km/h). 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. As always, drivers should use care when backing up a vehicle. Always look behind you, being sure to check for other vehicles, obstructions and blind spots. 2-115