Jeep 2013 Wrangler - Manual (Page 431)

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. This is accom-
plished by simply moving the shift lever to one of these
positions. 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.
The “4WD Indicator Light” (located in 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.
NOTE: Do not attempt to shift when only the front or
rear wheels are spinning. The transfer case is not
equipped with a synchronizer, and the front and rear
driveshaft speeds must be equal for a shift to take place.
Shifting while only the front or rear wheels are spinning
can cause damage to the transfer case.
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.
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