Ford 2003 Excursion Owner's Manual page 165

To help avoid personal injury, please read and understand the
limitations of the reverse sensing system as contained in this
section. Reverse sensing is only an aid for some (generally large and
fixed) objects when moving in reverse on a flat surface at "parking
speeds". Inclement weather may also affect the function of the RSS;
this may include reduced performance or a false activation.
To help avoid personal injury, always use caution when in R
(Reverse) and when using the RSS.
This system is not designed to prevent contact with small or
moving objects. The system is designed to provide a warning to
assist the driver in detecting large stationary objects to avoid damaging
the vehicle. The system may not detect smaller objects, particularly
those close to the ground.
The RSS detects obstacles within
approximately 1.8 meters (5.9 ft.) of
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 distance to the
obstacle is less than 25.0 cm (10
in.), the tone will sound
continuously. If the system detects a
stationary or receding object further
than 25.0 cm (10 in.) 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.
Driving
165