2009 JEEP GRAND CHEROKEE wheel torque

The least amount of accelerator pedal pressure to main-
tain the rocking motion, without spinning the wheels or
racing the engine, is most effective. Racing the engine or
spinning the wheels, due to the frustration of not freeing
the vehicle, may lead to transmission overheating and
failure. Allow the engine to idle with the shift lever in
NEUTRAL for at least one minute after every five
rocking-motion cycles. This will minimize overheating
and reduce the risk of transmission failure during pro-
longed efforts to free a stuck vehicle.
CAUTION!
When “rocking” a stuck vehicle by moving between
“First” and REVERSE, do not spin the wheels faster
than 15 mph (24 km/h), or drivetrain damage may
result.
FOUR-WHEEL DRIVE OPERATION
Quadra-Trac IOperating
Instructions/Precautions — If Equipped
The Quadra-Trac Iis a single-speed (HI range only)
transfer case, which provides convenient full-time four–
wheel drive. No driver interaction is required. The Brake
Traction Control System (BTC), which combines standard
ABS and Traction Control, provides resistance to any
wheel that is slipping to allow additional torque transfer
to wheels with traction.
NOTE:The Quadra-Trac Isystem is not appropriate
for conditions where 4WD LOW range is recommended.
Refer to “Off-Road Driving Tips” in this section.
296 STARTING AND OPERATING

Quadra-Drive IISystem — If Equipped
The optional Quadra-Drive IISystem features three
torque transfer couplings. The couplings include ELSD
(Electronic Limited-Slip Differential) front and rear axles
and Quadra-Trac IItransfer case. The optional ELSD
axles are fully automatic and require no driver input to
operate. Under normal driving conditions, the units
function as standard axles, balancing torque evenly be-
tween left and right wheels. With a traction difference
between left and right wheels, the coupling will sense a
speed difference. As one wheel begins to spin faster than
the other, torque will automatically transfer from the
wheel that has less traction, to the wheel that has traction.
While the transfer case and axle couplings differ in
design, their operation is similar. Follow the Quadra-Trac
IItransfer case shifting information, preceding this
section, for shifting this system.
ON-ROAD DRIVING TIPS
Utility vehicles have higher ground clearance and a
narrower track to make them capable of performing in a
wide variety of off-road applications. Specific design
characteristics give them a higher center of gravity than
ordinary cars.
An advantage of the higher ground clearance is a better
view of the road, allowing you to anticipate problems.
They are not designed for cornering at the same speeds as
conventional two-wheel drive vehicles any more than
low-slung sports cars are designed to perform satisfacto-
rily in off-road conditions. If at all possible, avoid sharp
turns or abrupt maneuvers. As with other vehicles of this
type, failure to operate this vehicle correctly may result in
loss of control or vehicle rollover.
STARTING AND OPERATING 301
5

Traction Downhill
Shift the transmission into a low gear, and the transfer
case into 4WD LOW range. Let the vehicle go slowly
down the hill with all four wheels turning against engine
compression drag. This will permit you to control the
vehicle speed and direction.
When descending mountains or hills, repeated braking
can cause brake fade with loss of braking control. Avoid
repeated heavy braking by downshifting the transmis-
sion whenever possible.
After Driving Off-Road
Off-road operation puts more stress on your vehicle than
does most on-road driving. After going off-road, it is
always a good idea to check for damage. That way you
can get any problems taken care of right away and have
your vehicle ready when you need it.
•Completely inspect the underbody of your vehicle.
Check tires, body structure, steering, suspension, and
exhaust system for damage.
•Check threaded fasteners for looseness, particularly on
the chassis, drivetrain components, steering, and sus-
pension. Retighten them, if required, and torque to the
values specified in the Service Manual.
•Check for accumulations of plants or brush. These
things could be a fire hazard. They might hide damage
to fuel lines, brake hoses, axle pinion seals, and
propeller shafts.
•After extended operation in mud, sand, water, or
similar dirty conditions, have brake rotors, wheels,
brake linings, and axle yokes inspected and cleaned as
soon as possible.
STARTING AND OPERATING 305
5

WARNING!
ABS (Anti-Lock Brake System) cannot prevent the
natural laws of physics from acting on the vehicle,
nor can it increase the traction afforded by prevailing
road conditions. ABS cannot prevent accidents, in-
cluding those resulting from excessive speed in
turns, driving on very slippery surfaces, or hydro-
planing. Only a safe, attentive, and skillful driver can
prevent accidents. The capabilities of an ABS-
equipped vehicle must never be exploited in a reck-
less or dangerous manner which could jeopardize the
user’s safety or the safety of others.
TCS (Traction Control System)
This system monitors the amount of wheel spin of each of
the driven wheels. If wheel spin is detected, brake
pressure is applied to the slipping wheel(s) and engine
power is reduced to provide enhanced acceleration andstability. A feature of the TCS system functions similar to
a limited-slip differential and controls the wheel spin
across a driven axle. If one wheel on a driven axle is
spinning faster than the other, the system will apply the
brake of the spinning wheel. This will allow more engine
torque to be applied to the wheel that is not spinning.
This feature remains active even if TCS and ESP are in
either the “Partial Off” or “Full Off” modes. Refer to “ESP
(Electronic Stability Program)” in this section for more
information.
BAS (Brake Assist System)
The BAS is designed to optimize the vehicle’s braking
capability during emergency braking maneuvers. The
system detects an emergency braking situation by sens-
ing the rate and amount of brake application and then
applies optimum pressure to the brakes. This can help
reduce braking distances. The BAS complements the
anti-lock brake system (ABS). Applying the brakes very
quickly results in the best BAS assistance. To receive the
STARTING AND OPERATING 313
5

wheel nut tightness is 95 ft lbs (130 N·m). If in doubt
about the correct tightness, have them checked with a
torque wrench by your authorized dealer or at a service
station.
10. Lower the jack to its fully closed position.
WARNING!
A loose tire or jack, thrown forward in a collision or
hard stop could endanger the occupants of the ve-
hicle. Always stow the jack parts and the spare tire in
the places provided.
11. Secure the tire, jack, and tools in their proper loca-
tions.
NOTE:A tire should be stowed with the “beauty” side
up. Storing the tire upside down may result in scratching
or damage to the wheel face. Continue winching up the
tire until you hear the winch “ratchet” three times.Double check to ensure the tire is snug against the
underbody of the vehicle. Damage to the winch cable
may result if the vehicle is driven with the tire loose.
WARNING!
Do not use power tools to winch the tire up or down.
Impact-type tools may damage the winch mecha-
nism.
12. Reinstall the plastic plug into the floor of the cargo
area.
JUMP-STARTING
If the vehicle has a discharged battery, booster cables may
be used to obtain a start from a booster battery or the
battery in another vehicle. This type of start can be
dangerous if done improperly, so follow this procedure
carefully.
398 WHAT TO DO IN EMERGENCIES

Safety.............................. 326
Sizes............................... 327
Spare Tire........................... 392
Spinning............................ 340
Tread Wear Indicators................... 340
Wheel Mounting...................... 397
Tongue Weight/Trailer Weight.............. 375
Torque Converter Clutch.................. 294
Tow Hooks, Emergency................... 400
Tow/Haul Indicator Light................. 190
Towing............................369,401
24-Hour Towing Assistance................ 97
Disabled Vehicle....................... 401
Guide.............................. 373
Recreational.......................... 382
Weight.............................. 373
Towing Assistance........................ 97
Traction Control......................... 313
Trailer Sway Control (TSC)................. 320Trailer Towing.......................... 369
Cooling System Tips.................... 382
Hitches............................. 372
Minimum Requirements................. 376
Trailer and Tongue Weight............... 375
Wiring.............................. 379
Trailer Towing Guide..................... 373
Trailer Weight.......................... 373
Transfer Case........................... 432
Maintenance......................... 432
Transmission
Automatic........................288,433
Maintenance......................... 433
Shifting............................. 286
Transmitter Battery Service
(Remote Keyless Entry).................... 25
Transmitter, Garage Door Opener (HomeLink) . . 154
Transmitter Programming
(Remote Keyless Entry).................... 21
INDEX 515
10