2009 Mercury Mariner Owner's Manual - Page 213

Driving The RSS detects obstacles up to 6 feet (1.8 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. The RSS automatically turns on when the gear selector is placed in R (Reverse) and the ignition is on. An RSS control located on the instrument panel allows the driver to turn the RSS on and off. To turn the RSS off, the ignition must be on. The system will remain off until either the RSS control is pressed again or the ignition is turned off, then on again. An indicator light on the control will illuminate when the system is turned off. If the indicator light illuminates when the RSS is not turned off, it may indicate a failure in the RSS. 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. 213 2009 Mariner (mrn) Owners Guide, 2nd Printing USA (fus)