FORD 2010 Expedition v.3 - Manual (Page 310)

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 value.
Audible Warnings
Distance to Object Warning
Speed above 2.5 mph (4 km/h)
up to 1.6 ft (.5 m) Solid
1.6 ft (.5 m) to 3.1 ft (1 m) Fast beep
3.1 ft (1 m) to 5.7 ft (1.8 m) Medium/fast beep
5.7 ft (1.8 m) to 9 ft (2.8 m) Medium beep
9 ft (2.8 m) to 13 ft (4 m) Medium/slow beep
13 ft (4 m) to 19.6 ft (6 m) Slow beep
Speed below 2.5 mph (4 km/h)
up to 1.4 ft (.4 m) Solid
1.4 ft (.4 m) to 3 ft (.9 m) Fast beep
3 ft (.9 m) to 4.5 ft (1.4 m) Medium beep
4.5 ft (1.4 m) to 6.3 ft (1.9 m) Medium/slow beep
6.3 ft (1.9 m) to 8.7 ft (2.6 m) Slow beep
8.7 ft (2.6 m) to 16.4 ft (5 m) No sound
The reverse sensing system is automatically enabled when the gearshift
lever is placed in R (Reverse) and the ignition is on. A control in the
message center allows the driver to disable the system, refer to Message
center in the Instrument Cluster chapter for more information.
Note: If the system cannot be turned off, refer to MyKey™ in the Locks
and Security chapter for more information.
The message center will indicate the system is off and will not allow the
driver to switch the system on to indicate a failure of the reverse sensing
system.
The radar sensor is located behind the rear bumper/fascia. Always
keep the rear bumper/fascia free from snow, ice and large
accumulations of dirt. These elements may cause the system to
operate inaccurately.
If the 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.
Driving
310
2010 Expedition (exd)
Owners Guide, 3rd Printing
USA (fus)