2004 JEEP GRAND CHEROKEE catalytic converter

7. Oil Pressure Gage
Indicates the engine oil pressure. This gage does
not measure oil level. Pressure varies with engine
speed, temperature, and oil viscosity. Normal oil pressure
will be midway between the lowest and highest limit
marks.
8. Sentry Key Indicator Light Ð If Equipped
Refer to ªSentry Key Immobilizer Systemº in
Section 2 of this manual for more information.
9. Malfunction Indicator Light
This light is part of an onboard diagnostic system
called OBD II which monitors engine and auto-
matic transmission control systems. This light
will illuminate when the ignition is in the ON position
before engine start. If the bulb does not come on when
turning the ignition key from OFF to ON, have the
condition checked promptly.Certain conditions such has a loose or missing gas cap,
poor fuel quality, etc. may illuminate the light after
engine start. The vehicle should be serviced if the light
stays on through several typical driving cycles. In most
situations, the vehicle will drive normally and will not
require towing.
When the engine is running, the ªMalfunction Indicator
Lightº may flash to alert of serious conditions that could
lead to immediate loss of power or severe catalytic
converter damage. The vehicle should be serviced as
soon as possible if this occurs.
10. Cruise Indicator Light
This indicator lights when the electronic speed
control system is turned ON.
11. Check Gages Warning Light
This light illuminates when the voltmeter, oil
pressure, or temperature gages indicate a reading
130 UNDERSTANDING YOUR INSTRUMENT PANEL

MMT In Gasoline
MMT is a manganese containing metallic additive that is
blended into some gasoline to increase octane. Gasoline
blended with MMT provides no performance advantage
beyond gasoline of the same octane number without
MMT. Gasoline blended with MMT reduces spark plug
life and reduces emission system performance in some
vehicles. The manufacturer recommends that gasoline
without MMT be used in your vehicle. The MMT content
of gasoline may not be indicated on the gasoline pump,
therefore, you should ask your gasoline retailer whether
or not his/her gasoline contains MMT.
It is even more important to look for gasoline without
MMT in Canada because MMT can be used at levels
higher than allowed in the United States. MMT is pro-
hibited in Federal and California reformulated gasoline.
Sulfur In Gasoline
If you live in the northeast United States, your vehicle
may have been designed to meet California low emission
standards with clean burning, low sulfur, California
gasoline. Gasoline sold outside of California is permitted
to have higher sulfur levels which may affect the perfor-
mance of the vehicle's catalytic converter. This may cause
the ªMalfunction Indicator Lightº to illuminate.
Illumination of this light while operating on high sulfur
gasoline does not necessarily mean your emission control
system is malfunctioning. The manufacturer recom-
mends that you try a different brand of unleaded gaso-
line having lower sulfur to determine if the problem is
fuel related prior to returning your vehicle to an autho-
rized dealer for service.
STARTING AND OPERATING 223
5

WARNING!
Do not attempt to push or tow your vehicle to get it
started. Unburned fuel could enter the catalytic
converter and, once the engine has started, ignite and
damage the converter and vehicle.
EMERGENCY TOW HOOKS Ð IF EQUIPPED
If your vehicle is equipped with tow hooks, they will be
mounted in the front of the vehicle.
CAUTION!
Tow hooks are for emergency use only, to rescue a
vehicle stranded off road. Do not use tow hooks for
tow truck hookup or highway towing. You could
damage your vehicle.
WARNING!
Stand clear of vehicles when pulling with tow
hooks. Tow straps and chains may break, causing
serious injury.
TOWING A DISABLED VEHICLE
The manufacturer recommends towing with all four
wheels off the ground. Acceptable methods are to tow the
vehicle on a flatbed or with one end of the vehicle raised
and the other end on a towing dolly.
248 WHAT TO DO IN EMERGENCIES

MAINTAINING YOUR VEHICLE
CONTENTS
m4.0L Engine...........................251
m4.7L/4.7 HO Engine.....................252
mOnboard Diagnostic System Ð OBD II........253
mEmissions Inspection And Maintenance
Programs............................254
mReplacement Parts......................255
mDealer Service.........................255
mMaintenance Procedures..................256
NEngine Oil..........................256NDrive Belts - Check Condition And Tension . . . 261
NSpark Plugs.........................261
NCatalytic Converter....................261
NCrankcase Emission Control System........263
NFuel Filter..........................263
NAir Cleaner Filter.....................264
NMaintenance-Free Battery................264
NAir Conditioner Maintenance.............265
NPower Steering Fluid Check..............266
7

Drive Belts - Check Condition and Tension
At the mileages shown in the appropriate ªMaintenance
Schedule,º check all drive belts for condition and proper
tension. Improper belt tension can cause belt slippage
and failure.
Inspect the drive belt for evidence of cuts, cracks, or
glazing and replace them if there is any sign of damage
which could result in belt failure. If adjustment is re-
quired, adjust the belts according to the specifications
and procedures shown in the Service Manual.
Special tools are required to properly measure tension
and to restore belt tension to factory specifications. Also,
check belt routing to make sure there is no interference
between the belts and other engine components.
Spark Plugs
Spark plugs must fire properly to assure engine perfor-
mance and emission control. New spark plugs should be
installed at the specified mileage. The entire set should be
replaced if there is any malfunction due to a faulty spark
plug. Refer to the ªVehicle Emission Control Informa-
tionº label in the engine compartment for spark plug
information.
Catalytic Converter
The catalytic converter requires the use of unleaded fuel
only. Leaded gasoline will destroy the effectiveness of the
converter as an emission control device.
Under normal operating conditions, the catalytic con-
verter will not require maintenance. However, it is im-
portant to keep the engine properly tuned to assure
proper catalyst operation and prevent possible catalyst
damage.
MAINTAINING YOUR VEHICLE 261
7

CAUTION!
Damage to the catalytic converter can result if your
vehicle is not kept in proper operating condition. In
the event of engine malfunction, particularly involv-
ing engine misfire or other apparent loss of perfor-
mance, have your vehicle serviced promptly. Contin-
ued operation of your vehicle with a severe
malfunction could cause the converter to overheat,
resulting in possible damage to the converter and
vehicle.
WARNING!
A hot exhaust system can start a fire if you park over
materials that can burn. Such materials might be
grass or leaves coming into contact with your ex-
haust system. Do not park or operate your vehicle in
areas where your exhaust system can contact any-
thing that can burn.
In unusual situations involving grossly malfunctioning
engine operation, a scorching odor may suggest severe
and abnormal catalyst overheating. If this occurs, stop
the vehicle, turn off the engine and allow it to cool.
Service, including a tune up to manufacturer's specifica-
tions, should be obtained immediately.
262 MAINTAINING YOUR VEHICLE

To minimize the possibility of catalytic converter dam-
age:
²Do not shut off the engine or interrupt the ignition
when the transmission is in gear and the vehicle is in
motion.
²Do not try to start the engine by pushing or towing the
vehicle.
²Do not idle the engine with any spark plug wires
disconnected or removed, such as when diagnostic
testing.
²Do not idle the engine for prolonged periods during
very rough idle or malfunctioning operating condi-
tions.
²Do not allow vehicle to run out of fuel.NOTE:Intentional tampering with emissions control
systems can result in civil penalties being assessed
against you.
Crankcase Emission Control System
Proper operation of this system depends on freedom
from sticking or plugging due to deposits. As vehicle
mileage builds up, the PCV valve and passages may
accumulate deposits. If a valve is not working properly,
replace it with a new valve. DO NOT ATTEMPT TO
CLEAN THE OLD PCV VALVE!
Check ventilation hose for indication of damage or
plugging deposits. Replace if necessary.
Fuel Filter
A plugged fuel filter can cause hard starting or limit the
speed at which a vehicle can be driven. Should an
excessive amount of dirt accumulate in the fuel tank,
frequent replacement of the fuel filter which is mounted
in the fuel tank may be necessary.
MAINTAINING YOUR VEHICLE 263
7

Cassette Tape and Player Maintenance......... 162
Cassette Tape Player...................143,147
Catalytic Converter...................... 261
Caution, Exhaust Gas...................... 51
CD Changer......................140,150,156
CD Player....................136,139,143,149
CD Player Maintenance................... 163
Cellular Phone.......................... 164
Center Lap Belts......................... 33
Chains, Tire............................ 220
Chart, Tire Sizing........................ 204
Check Engine Light...................... 130
Checks, Safety.........................52,53
Child Restraint.......................... 44
Child Restraint Tether Anchors............... 47
Child Safety Locks........................ 18
Climate Control......................... 164
Clock................................ 135
Compact Disc Maintenance................. 163Compact Spare Tire...................... 241
Compass...........................101,104
Compass Calibration..................... 104
Compass Variance....................... 105
Computer, Trip/Travel.................... 101
Console, Overhead....................... 89
Contract, Service........................ 320
Converter, Catalytic...................... 261
Cooling System......................... 269
Adding Coolant (Antifreeze).............. 271
Coolant Capacity...................... 291
Coolant Level......................... 272
Disposal of Used Coolant................ 270
Drain, Flush, and Refill.................. 270
Inspection........................... 269
Points to Remember.................... 273
Pressure Cap......................... 272
Radiator Cap......................... 272
Selection of Coolant..................270,291
330 INDEX