Jeep Wrangler2018 Owner's Manual page 322

320 STARTING AND OPERATING
For variable driving conditions, the 4WD AUTO mode can
be used. In this mode, the front axle is engaged, but the
vehicle's power is sent to the rear wheels. Four-wheel drive
will be automatically engaged when the vehicle senses a
loss of traction. Because the front axle is engaged, this
mode will result in lower fuel economy than the 2WD
mode.
In the event that additional traction is required, the transfer
case 4H and 4L positions can be used to lock the front and
rear driveshafts together, forcing the front and rear wheels
to rotate at the same speed. The 4H and 4L positions are
intended for loose, slippery road surfaces only and not
intended for normal driving. Driving in the 4H and 4L
positions on hard-surfaced roads will cause increased tire
wear and damage to the driveline components. Refer to
"Shifting Procedures" in this section for further informa-
tion on shifting into 4H or 4L.
The instrument cluster alerts the driver that the vehicle is
in four-wheel drive, and the front and rear driveshafts are
locked together. The light will illuminate when the transfer
case is shifted into the 4H position.
When operating your vehicle in 4L, the engine speed will
be approximately three times (four times for Rubicon
models) that of the 2H or 4H positions at a given road
speed. Take care not to overspeed the engine.
Proper operation of four-wheel drive vehicles depends on
tires of equal size, type, and circumference on each wheel.
Any difference will adversely affect shifting and cause
damage to the transfer case.
Because four-wheel drive provides improved traction,
there is a tendency to exceed safe turning and stopping
speeds. Do not go faster than road conditions permit.
WARNING!
You or others could be injured or killed if you leave the
vehicle unattended with the transfer case in the NEU-
TRAL (N) position without first fully engaging the
parking brake. The transfer case NEUTRAL (N) posi-
tion disengages both the front and rear driveshafts
from the powertrain, and will allow the vehicle to roll,
even if the automatic transmission is in PARK (or
manual transmission is in gear). The parking brake
should always be applied when the driver is not in the
vehicle.