From the 2007 owner manual page 142:

4WD Low RangeFull Off
This is the normal operating mode for ESP in 4WD low
range. Whenever the vehicle is started in 4WD low range,
or the transfer case (if equipped) is shifted from 4WD
high range or neutral to 4WD low range, the ESP system
will be in this mode. In 4WD low range, ESP and TCS,
except for the “limited slip” feature described in the TCS
section, are turned off until the vehicle reaches a speed of
40 mph (64 km/h). At 40 mph (64 km/h), the normal ESP
stability function returns but TCS remains off. When the
vehicle speed drops below 35 mph (56 km/h), the ESP
system shuts off. ESP is off at low vehicle speeds in 4WD
low range so that it will not interfere with off-road
driving but ESP function returns to provide the stability
feature at speeds above 40 mph (64 km/h). The ESP/
TCS Indicator Light will always be illuminated in 4WD
low range when ESP is off.
NOTE: The “ESP OFF” message will display and the
audible chime will sound when the gear selector is
placed into the “P” (Park) position from any position
other than “P” (Park), and then moved out of the “P”
(Park) position. This will occur even if the message was
previously cleared
From the 2008 owner manual page 142-3:

4WD Low RangeFull Off
This is the normal operating mode for ESP in 4WD low
range. Whenever the vehicle is started in 4WD low range,
or the transfer case (if equipped) is shifted from 4WD
high range or neutral to 4WD low range, the ESP system
will be in this “Full Off” mode. In 4WD low range, ESP
and TCS, except for the “limited slip” feature described
in the TCS section, are turned off until the vehicle reaches
a speed of 40 mph (64 km/h). At 40 mph (64 km/h), the
normal ESP stability function returns but TCS remains
off. When the vehicle speed drops below 35 mph (56
km/h), the ESP system shuts off. ESP is deactivated at
low vehicle speeds in 4WD low range so that it will not
interfere with off-road driving but ESP function returns
to provide the stability feature at speeds above 40 mph
(64 km/h). The 9ESP/TCS Indicator Light9 will always be
illuminated in 4WD low range when ESP is off.
NOTE: The “ESP OFF” message will display and the
audible chime will sound when the gear selector is
placed into the “P” (Park) position from any other
position, and then moved out of the “P” (Park) position.
This will occur even if the message was previously
cleared