Jeep Grand Cherokee 2013 Operating Information Manual page 238

DRIVE
This range should be used for most city and
highway driving. It provides the smoothest up-
shifts and downshifts, and the best fuel
economy. The transmission automatically up-
shifts through underdrive first and second
gears, direct third gear and overdrive fourth and
fifth gears. The DRIVE position provides opti-
mum driving characteristics under all normal
operating conditions.
To access all six available gears, you must use
the Electronic Range Select (ERS) shift control
(refer to "Electronic Range Select (ERS) Opera-
tion" in this section).
When frequent transmission shifting occurs
(such as when operating the vehicle under
heavy loading conditions, in hilly terrain, travel-
ing into strong head winds, or while towing
heavy trailers), use the Electronic Range Select
(ERS) shift control (refer to "Electronic Range
Select (ERS) Operation" in this section) to se-
lect a lower gear range. Under these conditions,
using a lower gear range will improve perfor-
mance and extend transmission life by reducing
excessive shifting and heat buildup.
234
If the transmission temperature exceeds normal
operating limits, the powertrain controller will
modify the transmission shift schedule and ex-
pand the range of torque converter clutch en-
gagement. This is done to prevent transmission
damage due to overheating.
If the transmission becomes extremely hot or is
in danger of overheating, the "Transmission
Temperature Warning Light" may illuminate and
the transmission may operate differently until
the transmission cools down.
NOTE:
Use caution when operating a heavily
loaded vehicle at low speeds (such as tow-
ing a trailer up a steep grade, or in stop-
and-go traffic) during hot weather. In these
conditions, torque converter slip can im-
pose a significant additional heat load on
the cooling system. Downshifting the trans-
mission to the lowest possible gear (when
climbing a grade), or shifting to NEUTRAL
(when stopped in heavy traffic) can help to
reduce this excess heat generation.
During cold temperatures, transmission opera-
tion may be modified depending on engine and
transmission temperature as well as vehicle
speed. This feature improves warm up time of
the engine and transmission to achieve maxi-
mum efficiency. Engagement of both the torque
converter clutch and the top overdrive gear are
inhibited until the transmission fluid is warm
(refer to the "Note" under "Torque Converter
Clutch" in this section). During extremely cold
temperatures (-16°F [-27°C] or below), opera-
tion may briefly be limited to first and direct
gears only. Normal operation will resume once
the transmission temperature has risen to a
suitable level.
Transmission Limp Home Mode
Transmission function is monitored electroni-
cally for abnormal conditions. If a condition is
detected that could result in transmission dam-
age, Transmission Limp Home Mode is acti-
vated. In this mode, the transmission remains in
direct gear regardless of which forward gear is
selected. PARK, REVERSE, and NEUTRAL will
continue to operate. The Malfunction Indicator
Light (MIL) may be illuminated. Limp Home
Mode allows the vehicle to be driven to an
authorized dealer for service without damaging
the transmission.