Jeep 2004 Grand Cherokee Owner's Manual page 187

mode allows the front and rear wheels to rotate at
different speeds which eliminates driveline binding and
component wear that is normally associated with driving
the vehicle in the 4 PART TIME position on dry hard
surfaced roads. This feature provides the safety, security,
and convenience of operating in 4 wheel drive at all times
regardless of road conditions.
When additional traction is required, the 4 PART TIME
and 4LO positions can be used to lock the front and rear
driveshafts together through the transfer case inter-axle
differential and force the front and rear driveshafts to
rotate at the same speed. This is accomplished by simply
moving the shift lever to these positions. The 4 PART
TIME and 4LO positions are intended for loose, slippery
road surfaces only. Driving in the 4 PART TIME and 4LO
positions on dry hard surfaced roads may cause in-
creased tire wear and damage to driveline components.
STARTING AND OPERATING 187
The PART TIME indicator light, located in the instrument
panel, alerts the driver that a four wheel drive mode
which locks the front and rear driveshafts together has
been selected. This light illuminates when the transfer
case is shifted to either the 4 PART TIME or 4LO
positions. There is no light for the 2WD, 4 FULL TIME, or
N (Neutral) positions.
NOTE: Do not attempt to make a shift while only the
front or rear wheels are spinning. The Selec-Trac trans-
fer case is not equipped with a synchronizer and there-
fore the front and rear driveshaft speeds must be equal
for the shift to take place. Shifting while only the front or
rear wheels are spinning can cause damage to the trans-
fer case.
When operating your vehicle in 4LO, the engine speed is
approximately three times that of the 4 ALL TIME
position at a given road speed. Take care not to overspeed
the engine and do not exceed 25 mph (40 km/h).
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