2004 JEEP GRAND CHEROKEE wheel size

units. A large quantity of nontoxic gas is generated to
inflate the front airbags. Different airbag inflation rates
are possible, these rates are determined by the front
airbag control module based on collision severity. The
steering wheel hub trim cover and the upper right side
of the instrument panel separate and fold out of the
way as the bags inflate to their full size. The bags fully
inflate in about 30±70 milliseconds. This is about half
of the time it takes to blink your eyes. The bags then
quickly deflate while helping to restrain the driver and
front passenger.
The driver front airbag gas is vented through the
airbag material towards the instrument panel. The
passenger front airbag gas is vented through the
airbag material on the sides of the airbag. In this way,
the airbags do not interfere with your control of the
vehicle.²TheSide Impact SRS Window Bagsare designed to
activate only in certain side collisions. When the airbag
control module (ACM), along with the remote side
impact sensors detects a side impact collision requir-
ing the window bags to inflate, it signals the inflators
on the crash side of the vehicle. A quantity of nontoxic
gas is generated to inflate the window bag. The
inflating window bag pushes the outside edge of the
headliner out of the way and covers the window. The
airbag inflates in about 30 milliseconds (about one
quarter of the time it takes to blink your eyes) with
enough force to injure you if you are not belted and
seated properly, or if items are positioned in the area
where the window bag inflates. This especially applies
to children. The window bag is only about 3
1¤2inches
(9 cm) thick when it is inflated.
²TheKnee Impact Bolstershelp protect the knees of
the driver and the front passenger's, and position
everyone for the best interaction with the front airbag.
THINGS TO KNOW BEFORE STARTING YOUR VEHICLE 41
2

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 if you leave the
vehicle unattended with the transfer case in the N
(Neutral) position without first fully engaging the
parking brake. The transfer case N (Neutral) position
disengages both the front and rear driveshafts from
the powertrain and will allow the vehicle to move
regardless of the transmission position. The parking
brake should always be applied when the driver is
not in the vehicle.
Shift Positions
For additional information on the appropriate use of each
transfer case mode position, see the information below:
2WD
Rear Wheel Drive High Range Ð Normal street and
highway driving. Dry hard surfaced roads.
4 PART TIME
Part Time 4 Wheel Drive High Range Ð Locks the
transfer case inter-axle differential. Forces the front and
rear wheels to rotate at the same speed. Additional
traction for loose, slippery road surfaces only.
4 FULL TIME
Full Time 4 Wheel Drive High Range Ð Employs inter-
axle differential. Allows front and rear wheels to rotate at
different speeds. All roads surfaces.
188 STARTING AND OPERATING

5 km/h). Avoid attempting to engage or disengage 4LO
with the vehicle moving faster than 2 to 3 mph (3 to 5
km/h).
Quadra-Trac IITOperating
Instructions/Precautions Ð If Equipped
The Quadra-Trac IIttransfer case is fully automatic in the
normal driving 4 ALL TIME mode. The Quadra-Trac IIt
transfer case provides three mode positions Ð four wheel
drive high range, neutral, and four wheel drive low
range.
This transfer case is fully automatic in the 4 ALL TIME
mode. The 4 ALL TIME mode transmits torque to the rear
axle during normal driving, similar to a rear wheel drive
vehicle. When speed difference is increased between the
front and rear driveshafts the majority of engine torque
can be transmitted to the front driveshaft.
When additional traction is required, the 4LO position
can be used to lock the front and rear driveshafts togetherand force the front and rear wheels to rotate at the same
speed. The 4LO position is intended for loose, slippery
road surfaces only. Driving in the 4LO position on dry
hard surfaced roads may cause increased tire wear and
damage to driveline components.
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).
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.
STARTING AND OPERATING 191
5

ANTI-LOCK BRAKE SYSTEM
The Anti-Lock Brake System (ABS) is designed to aid the
driver in maintaining vehicle control under adverse
braking conditions. The system operates with a separate
computer to modulate hydraulic pressure to prevent
wheel lock-up and help avoid skidding on slippery
surfaces.
All vehicle wheels and tires must be the same size and
type and tires must be properly inflated to produce
accurate signals for the computer.
WARNING!
Significant over or under inflation of tires, or mixing
sizes of tires or wheels on the vehicle can lead to loss
of braking effectiveness.
The Anti-Lock Brake System conducts a low-speed self-
test at about 12 mph (20 km/h). If you have your foot
lightly on the brake while this test is occurring you may
feel slight pedal movement. The movement can be more
apparent on ice and snow. This is normal.
The Anti-Lock Brake System pump motor runs during
the self-test at 12 mph (20 km/h) and during an ABS stop.
The pump motor makes a low humming noise during
operation, which is normal.
WARNING!
Pumping of the Anti-Lock Brakes will diminish
their effectiveness and may lead to an accident.
Pumping makes the stopping distance longer. Just
press firmly on your brake pedal when you need to
slow down or stop.
STARTING AND OPERATING 197
5

WARNING!
²Do not use a tire, wheel size or rating other than that
specified for your vehicle. Some combinations of
unapproved tires and wheels may change suspen-
sion dimensions and performance characteristics,
resulting in changes to steering, handling, and brak-
ing of your vehicle. This can cause unpredictable
handling and stress to steering and suspension com-
ponents. You could lose control and have an accident
resulting in serious injury or death. Use only the tire
and wheel sizes with load ratings approved for your
vehicle.
²Never use a tire smaller than the minimum tire size
listed on your vehicle's tire label. Using a smaller tire
could result in tire overloading and failure. You
could lose control and have an accident.
²Failure to equip your vehicle with tires having
adequate speed capability can result in sudden tire
failure and loss of vehicle control.
²Overloading your tires is dangerous. Overloading
can cause tire failure. Use tires of the recommended
load capacity for your vehicle - never overload them.
CAUTION!
Replacing original tires with tires of a different size
may result in false speedometer and odometer read-
ings. Check with your dealer before replacing tires
with a different size.
216 STARTING AND OPERATING

Alignment and Balance
The suspension components of your vehicle should be
inspected and aligned when needed, to obtain maximum
tire tread life.
Poor suspension alignment may result in:
²reduced tread life;
²uneven tire wear, such as feathering and one-sided
wear;
²vehicle pull to the right or to the left.
Tires may also cause the vehicle to pull left or right.
Alignment will not correct this problem. See your dealer
for proper diagnosis of the problem.
Improper alignment will not normally cause vehicle
vibration, which may be a result of tire and wheel
out-of-balance. Proper balancing will reduce vibration
and avoid tire cupping and spotty wear.
TIRE PRESSURE MONITOR SYSTEM Ð IF
EQUIPPED
The Tire Pressure Monitor System (TPM) monitors the
pressure in all 4 road tires and the full size spare (5 Tire
TPM System Only). The TPM system uses wireless
technology to monitor tire pressure levels. Sensors,
mounted to each wheel as part of the valve stem, transmit
tire pressure readings to a receiver located in the over-
head console. The tire pressure status is shown in the
Electronic Vehicle Information Center (EVIC) display.
Refer to ªOverhead Consoleº in Section 3 for more
information. The TPM system functions even when the
EVIC is not set on the tire pressure display screen.
The TPM system informs you of a low or high tire
pressure condition. If this occurs, correct your tire infla-
tion pressure as soon as possible, and inspect all of your
tires. Be sure to use a high quality gauge when adjusting
pressure. The TPM system is designed to monitor your
tire pressure but will not function as a tire pressure
STARTING AND OPERATING 217
5

gauge. There will be a delay between the instant you
adjust the air pressure in a tire and when the system
updates the display. The TPM system is not intended to
provide you with notification of rapid air loss.
The following chart indicates the TPM system pressure
levels. A threshold is the level at which the TPM system
provides you with an indication.
High Pressure Threshold 45 psi (310 kPa )
Placard Pressure (Cold) 33 psi (227 kPa)
Low Pressure Threshold 25 psi (172 kPa)
NOTE: A TPM system does not replace normal tire
maintenance.
CAUTION!
The TPM system has been optimized for the original
equipment tires and wheels. TPM system pressures
have been established for the tire size equipped on
your vehicle. Undesirable operation or sensor dam-
age may result when using replacement equipment
that is not of the same size, type, and/or style.
Aftermarket wheels can cause sensor damage. Do
not use tire sealant or balance beads if your vehicle
is equipped with TPM system as damage to the
sensors may result.
Tire Pressure Monitor System Tire/Wheel
Rotation and Sensor Replacement Ð If Equipped
With the 5 Tire TPM System, if a road tire and wheel is
replaced by the spare, the TPM system will detect the
swap automatically (after the ignition has been cycled)
218 STARTING AND OPERATING

Supplemental Restraint System - Airbag........ 35
System, Navigation...................... 152
Tachometer............................ 129
Tape Player............................ 147
Temperature Control, Automatic............. 167
Temperature Gauge, Engine Coolant.......... 131
Tether Anchor, Child Restraint............... 47
Theft System Arming...................... 23
Theft System Disarming.................... 23
Tie Down Hooks, Cargo................... 119
Tilt Steering Column...................... 84
Time Delay, Headlight..................... 80
Tire and Loading Information Placard......... 207
Tire Identification Number (TIN)............. 206
Tire Markings.......................... 203
Tire Safety Information.................... 203
Tires ...............................53,211
Air Pressure.......................... 212Alignment and Balance.................. 217
Chains.............................. 220
Changing.........................238,242
Compact Spare........................ 241
General Information.................... 211
High Speed.......................... 213
Inflation Pressures..................... 212
Jacking............................. 242
Load Capacity.....................207,208
Pressure Monitor System...............92,217
Radial.............................. 214
Replacement......................... 215
Rotation..........................218,220
Safety............................53,203
Sizes............................... 204
Spare Tire........................... 239
Spinning............................ 214
Tread Wear Indicators................... 215
Wheel Mounting....................... 244
342 INDEX