2005 JEEP GRAND CHEROKEE Engine

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.
Materials Added To Fuel
All gasoline sold in the United States is required to
contain effective detergent additives. Use of additional
detergents or other additives is not needed under normal
conditions.
Fuel System Cautions
CAUTION!
Follow these guidelines to maintain your vehicle’s
performance:
•The use of leaded gas is prohibited by Federal law.
Using leaded gasoline can impair engine performance,
damage the emission control system.
STARTING AND OPERATING 279
5

•An out-of-tune engine, or certain fuel or ignition
malfunctions, can cause the catalytic converter to
overheat. If you notice a pungent burning odor or
some light smoke, your engine may be out of tune or
malfunctioning and may require immediate service.
Contact your dealer for service assistance.
•The use of fuel additives which are now being sold as
octane enhancers is not recommended. Most of these
products contain high concentrations of methanol.
Fuel system damage or vehicle performance problems
resulting from the use of such fuels or additives is not
the responsibility of the manufacturer.
NOTE:Intentional tampering with emissions control
systems can result in civil penalties being assessed
against you.
Carbon Monoxide Warnings
WARNING!
Carbon monoxide (CO) in exhaust gases is deadly.
Follow the precautions below to prevent carbon
monoxide poisoning:
•Do not inhale exhaust gases. They contain carbon
monoxide, a colorless and odorless gas which can kill.
Never run the engine in a closed area, such as a
garage, and never sit in a parked vehicle with the
engine running for an extended period. If the vehicle is
stopped in an open area with the engine running for
more than a short period, adjust the ventilation system
to force fresh, outside air into the vehicle.
280 STARTING AND OPERATING

CAUTION!
Damage to the fuel system or emission control
system could result from using an improper fuel cap
(gas cap). A poorly fitting cap could let impurities
into the fuel system. Also, a poorly fitting after-
market cap can cause the MIL (Malfunction Indica-
tor Light) to illuminate, due to fuel vapors escaping
from the system.
•Turn the engine off.
•Rotate the fuel cap to the left to remove.
•To replace the cap, insert it into the filler neck and
tighten the cap about 1/4 turn until you hear one click.
This is an indication that the cap is properly tightened.
•Make sure that the fuel cap tether strap is not caught
under the fuel cap.
CAUTION!
To avoid fuel spillage and overfilling, do not “top
off” the fuel tank after filling.
NOTE:When the fuel nozzle “clicks” or shuts off, the
fuel tank is full.
Loose Fuel Filler Cap Message
If the vehicle diagnostic system determines that the fuel
filler cap is loose, improperly installed, or damaged, a
“CHECK GAS CAP” message will be displayed in the
EVIC (Electronic Vehicle Information Center). Refer to
“Electronic Vehicle Information Center” in Section 4 of
this manual. Tighten the fuel filler cap properly and press
the odometer reset button to turn the message off. If the
problem continues, the message will appear the next time
the vehicle is started. Refer to “Onboard Diagnostic
System — OBDII” in Section 7 of this manual for more
information.
282 STARTING AND OPERATING

WARNING!
•Remove the fuel cap (gas cap) slowly to prevent
fuel spray from the filler neck which may cause
injury.
•The volatility of some gasoline may cause a
buildup of pressure in the fuel tank that may
increase while you drive. This pressure can result
in a spray of gasoline and/or vapors when the cap
is removed from a hot vehicle. Removing the cap
slowly allows the pressure to vent and prevents
fuel spray.
•Never have any smoking materials lit in or near
the vehicle when the fuel cap is removed or the
tank filled.
•Never add fuel to the vehicle when the engine is
running.
WARNING!
A fire may result if gasoline is pumped into a
portable container that is inside of a vehicle. You
could be burned. Always place gas containers on the
ground while filling.
TRAILER TOWING
In this section you will find information on limits to the
type of towing you can reasonably do with your vehicle.
And you will find safety tips. Before towing a trailer
carefully review this information to tow your load as
efficiently and safely as possible.
To maintain warranty coverage, follow the requirements
and recommendations in this manual concerning ve-
hicles used for trailer towing.
Perform maintenance services as prescribed in the appro-
priate “Maintenance Schedule.” Refer to Section 8 of this
STARTING AND OPERATING 283
5

manual. When your vehicle is used for trailer towing,
never exceed the gross axle weight rating (GAWR) by the
addition of:
•The tongue weight of the trailer.
•The weight of any other type of cargo or equipment
put in or on your vehicle.
WARNING!
Improper towing can lead to an injury accident.
Follow these guidelines to make your trailer towing
as safe as possible:
•Be sure a trailer is loaded heavier in front, about 10%
to 15% of gross trailer weight. Loads balanced over the
wheels or heavier in the rear cause the trailer to sway
severelyside to side which will cause loss of control ofthe vehicle and trailer. Failure to load trailers heavier
in front is the cause of many trailer related accidents.
•Donotinterconnect the hydraulic brake system of
your vehicle with that of the trailer. This could cause
inadequate braking and possible personal injury.
•Trailer brakes are required for trailers in excess of
2,000 lbs (907 kg).
•Donotconnect a trailer lighting system directly to the
lighting system of your vehicle. Use an approved
trailer wiring harness. Failure to do so could damage
the vehicle electrical system and/or result in personal
injury.
•When hauling cargo or towing a trailer,do notover-
load your vehicle or trailer. Overloading can cause a
loss of control, poor performance or damage to brakes,
axle, engine, transmission, steering, suspension, body
structure or tires.
284 STARTING AND OPERATING

•Make certain that the load is secured in the trailer and
will not shift during travel.
•It is recommended thatanyhitches installed on your
vehicle be factory installed, or installed by a dealer
using factory approved parts. Factory approved parts
are specifically engineered with your vehicle’s perfor-
mance in mind, including the possibility that it will be
involved in an accident. Other hitches may not have
been so engineered. Vehicle performance, including
vehicle damage in an accident situation, may therefore
be different.
•If trailer towing is required and your vehicle is not
equipped with a trailer tow package, the Mopar
accessory towing harnesses are the only approved
method to provide for trailer lights. These harnesses
are designed to provide current to the trailer lights but
bypass the module designed to monitor tail lights.
Refer to the package instructions for details.
Trailer and Tongue Weight
Gross Trailer Weight (GTW) means the weight of the
trailer plus the weight of all cargo, consumables and
equipment loaded on the trailer when in actual under-
way towing condition. The best way to measure GTW is
to put your fully loaded trailer on a vehicle scale. The
entire weight of the trailer must be supported by the
scale.
Always load a trailer with 60% of the cargo weight in the
front of the trailer. This places approximately 10% to 15%
of the GTW on the tow hitch of your vehicle. This portion
of the GTW becomes the tongue weight.
Trailer sway control and equalizing hitch are required for
tongue weights above 350 lbs (159 kg)., i.e., trailer
weights heavier than 3,500 lbs (1 587 kg).
STARTING AND OPERATING 285
5

Cooling System Tips—Trailer Towing
To reduce potential for engine and transmission over-
heating in high ambient conditions, take the following
actions:
•City Traffic
When stopped, put transmission in N (Neutral) and
increase engine idle speed.
•Highway Driving
Reduce speed.
•Air Conditioning
Turn off temporarily.
To reduce the potential for transmission overheating,
turn the “TOW/HAUL” feature on when driving in hilly
areas or downshift the transmission to the next lower
gear range to eliminate excessive transmission shifting.
This action will also reduce the possibility of transmis-
sion overheating and provide better engine braking.
7–Pin Connector
STARTING AND OPERATING 287
5

TRAILER TOWING CAPABILITY
Engine Model GVWR
(Gross Vehice Wt.
Rating)GCWR
(Gross Combined
Wt. Rating)Hitch Type Max. GTW
(Gross Trailer Wt.)Max. Tongue Wt.
(See Note 1)
3.7L 4x2 5,700 lbs (2 585 kg) 8,000 lbs (3 629 kg) Class II 3,500 lbs (1 587 kg) 525 lbs (238 kg)
3.7L 4x4 5,900 lbs (2 676 kg) 8,200 lbs (3 719 kg) Class II 3,500 lbs (1 587 kg) 525 kbs (238 kg)
4.7L 4x2 6,010 lbs (2 726 kg) 11,200 lbs (5 080 kg) Class IV 6,500 lbs (2 948 kg) 720 lbs (327 kg)
4.7L 4x4 6,100 lbs (2 767 kg) 11,450 lbs (5 194 kg) Class IV 6,500 lbs (2 948 kg) 720 lbs (327 kg)
5.7L 4x4 6,150 lbs (2 789 kg) 12,200 lbs (5 534 kg) Class IV 7,200 lbs (3 266 kg) 720 lbs (327 kg)
Note 1 – The towing vehicle payload should be reduced
by the tongue load (for a dead weight hitch) to keep the
rear axle loading below GAWR (Gross Axle Weight
Rating) of 3,200 lbs (1 451 kg).
STARTING AND OPERATING 289
5