2005 Ford Expedition Owner's Manual - Page 275

Driving The RSS detects obstacles up to six feet (two meters) from the rear bumper with a decreased coverage area at the outer corners of the bumper, (refer to the figures for approximate zone coverage areas). As you move closer to the obstacle, the rate of the tone increases. When the obstacle is less than 10 inches (25.0 cm) away, the tone will sound continuously. If the RSS detects a stationary or receding object further than 10 inches (25.0 cm) from the side of the vehicle, the tone will sound for only three seconds. Once the system detects an object approaching, the tone will sound again. While receiving a warning the radio volume will be reduced to a predetermined level. After the warning goes away, the radio will return to the previous volume. The radio volume may be overridden using the radio volume control. Whenever a warning is received, the radio volume will be lowered to a volume that will allow the tones to be heard. The radio volume will return to the previous level after the warning goes away. The system is automatically enabled when the gear selector is placed in R (Reverse) and the ignition is ON. The RSS control in the message center allows the driver to disable the system only when the ignition is ON and the gear selector in R (Reverse). Keep the RSS sensors (located on the rear bumper/fascia) free from snow, ice and large accumulations of dirt (do not clean the sensors with sharp objects). If the sensors are covered, it will affect the accuracy of the RSS. If your vehicle sustains damage to the rear bumper/fascia, leaving it misaligned or bent, the sensing zone may be altered causing inaccurate measurement of obstacles or false alarms. 275 2005 Expedition (exd) Owners Guide (post-2002-fmt) USA (fus)