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To check if tires are even, lay a straight edge across all
four tires. The straight edge should touch all the tires.
CAUTION!4500/5500 Dual Rear Tires have only one approved
direction of rotation. This is to accommodate the
asymmetrical design (tread pattern) of the On/Off
road tire.
• When replacing a flat, the spare tire may have to
be remounted on the rim or installed at a different
location to maintain the correct placement of the
tire on the wheel relative to the tire/wheel position
on the vehicle. For example, if the spare is used to
replace an outer rear tire it will have to be re-
mounted on the rim so that the wheel is dished
inward. That way the tread design of asymmetrical
tires will maintain proper position. FUEL REQUIREMENTS
The 5.7L engine is designed to meet all
emissions regulations and provide satisfac-
tory fuel economy and performance when
using high-quality unleaded gasoline hav-
ing an octane range of 87 to 89. The manu-
facturer recommends the use of 89 octane
for optimum performance. The use of premium gasoline
is not recommended, as it will not provide any benefit
over regular gasoline in these engines.
Light spark knock at low engine speeds is not harmful to
your engine. However, continued heavy spark knock at
high speeds can cause damage and immediate service is
required.
Poor quality gasoline can cause problems such as hard
starting, stalling and hesitations. If you experience these
symptoms, try another brand of “regular” gasoline be-
fore considering service for the vehicle.
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E-85 Usage In Non-Flex Fuel Vehicles
Non-FFV vehicles are compatible with gasoline contain-
ing 10% ethanol (E10). Gasoline with higher ethanol
content may void the vehicle’s warranty.
If a Non-FFV vehicle is inadvertently fueled with E-85
fuel, the engine will have some or all of these symptoms:
• operate in a lean mode
• OBD II “Malfunction Indicator Light” on
• poor engine performance
• poor cold start and cold drivability
• increased risk for fuel system component corrosion
To fix a Non-FFV vehicle inadvertently fueled once with
E-85 perform the following:
• drain the fuel tank (see your authorized dealer)
• change the engine oil and oil filter • disconnect and reconnect the battery to reset the
engine controller memory
More extensive repairs will be required for prolonged
exposure to E-85 fuel.
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 the gasoline contains MMT. It is even more
important to look for gasolines without MMT in Canada,
because MMT can be used at levels higher than those
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allowed in the United States. MMT is prohibited in
Federal and California reformulated gasoline.
Materials Added To Fuel
All gasolines sold in the United States are required to
contain effective detergent additives. Use of additional
detergents or other additives is not needed under normal
conditions and would result in unnecessary cost. There-
fore, you should not have to add anything to the fuel.
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 perfor-
mance, damage the emission control system.
(Continued) CAUTION! (Continued)• 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 authorized dealer for service
assistance.
• When pulling a heavy load or driving a fully-
loaded vehicle when the humidity is low and the
temperature is high, use a premium unleaded fuel
to help prevent spark knock. If spark knock per-
sists, lighten the load, or engine piston damage
may result.
(Continued)320 STARTING AND OPERATING
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WARNING! (Continued)• Guard against carbon monoxide with proper
maintenance. Have the exhaust system inspected
every time the vehicle is raised. Have any abnor-
mal conditions repaired promptly. Until repaired,
drive with all side windows fully open.
ADDING FUEL
The fuel tank filler tube has a restricting door about 2 in
(50 mm) inside the opening. If using a portable fuel
container, it should have a flexible nozzle long enough to
force open the restricting door. CAUTION!• Damage to the fuel system or emissions control
system could result from using an improper fuel
tank filler tube cap (gas cap). A poorly fitting cap
could let impurities into the fuel system. Also, a
poorly-fitted aftermarket cap can cause the MIL
(Malfunction Indicator Light) to illuminate due to
fuel vapors escaping from the system.
• A poorly fitting gas cap may cause the MIL to turn
on.
• 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.322 STARTING AND OPERATING
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WARNING!• Never have any smoking materials lit in or near
the vehicle when the gas cap is removed or the
tank is being filled.
• Never add fuel to the vehicle when the engine is
running. This is in violation of most state and
federal fire regulations and may cause the MIL to
turn on.
NOTE: Tighten the gas cap 1/4 turn until you hear one
click. This is an indication that the cap is properly
tightened.
If the gas cap is not tightened properly, the Malfunction
Indicator Light will come on, Be sure the gas cap is
tightened every time the vehicle is refueled. 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.
Loose Fuel Filler Cap Message
If the vehicle diagnostic system determines
that the fuel filler cap is loose, improperly
installed, or damaged, a loose gascap indicator
will display in the EVIC telltale display area.
Refer to “Electronic Vehicle Information Center (EVIC) in
“Understanding Your Instrument Panel” for further in-
formation. Tighten the fuel filler cap properly and press
the SELECT button to turn off the message. If the
problem continues, the message will appear the next time
the vehicle is started.
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Fifth-Wheel Hitch
The fifth-wheel hitch is a special high platform with a
coupling that mounts over the rear axle of the tow vehicle
in the truck bed. It connects a vehicle and fifth-wheel
trailer with a coupling king pin.
Gooseneck Hitch
The gooseneck hitch employs a pivoted coupling arm
which attaches to a ball mounted in the bed of a pickup
truck. The coupling arm connects to the hitch mounted
over the rear axle in the truck bed.
Trailer Hitch Classification
Your vehicle may be factory equipped for safe towing of
trailers weighing over 5,000 lbs (2 268 kg) with the
optional Trailer Tow Prep Package. See your authorized
dealer for package content.
The following chart provides the industry standard for
the maximum trailer weight a given trailer hitch class can
tow and should be used to assist you in selecting the correct trailer hitch for your intended towing condition.
Refer to “Trailer Towing Weights (Maximum Trailer
Weight Ratings)” for the website address that contains
the necessary information for your specific drivetrain.
Trailer Hitch Classification Definitions
Class Max. Trailer Hitch Industry
Standards
Class I - Light Duty 2,000 lbs (907 kg)
Class II - Medium
Duty 3,500 lbs (1587 kg)
Class III - Heavy Duty 5,000 lbs (2268 kg)
Class IV - Extra
Heavy Duty 10,000 lbs (4540 kg)
Fifth Wheel/
Gooseneck Greater than 10,000 lbs
(4540 kg)
Refer to the “Trailer Towing Weights (Maximum
Trailer Weight Ratings)” for the Maximum Gross
Trailer Weight (GTW) towable for your given drive-
train. 5 STARTING AND OPERATING 329
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NOTE: This module has been designed and verified for
electric trailer brakes. To determine the type of brakes on
your trailer, check with your trailer manufacturer or
dealer. The user interface consists of the following:
GAIN/ Brake Output Power Display
Shows the current GAIN setting.
This display may also be used to display diagnostic
information, if needed.
• SC — Short Circuit to Ground
• Sb — Short to Battery
• CF — Controller Fault – If this message appears on the
display, see your authorized dealer.
When the vehicle brakes are applied, the display will no
longer show GAIN and will change to the output to the
trailer brakes.
Manual Brake Control Lever
Slide the manual brake control lever to the right to
activate power to the trailer’s electric brakes independent
of the tow vehicle’s brakes. If the manual brake control1 — GAIN/Brake Output Power Display
2 — Manual Brake Control Lever
3 — Trailer Brake Status Indicator Light
4 — GAIN Adjustment Buttons
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lever is activated while the brake is also applied, the
greater of the two inputs determines the power sent to
the trailer brakes.
The trailer and the vehicle’s brake lamps will come on
when either vehicle braking or manual trailer brakes are
applied.
Trailer Brake Status Indicator Light
This light indicates the trailer electrical connection status.
If no electrical connection is detected after the ignition is
turned on, pressing the GAIN adjustment button or
sliding the manual brake control lever will display the
GAIN setting for 10 seconds and the “Trailer Brake Status
Indicator Light” will not be displayed.
If a fault is detected in the trailer wiring or the Integrated
Trailer Brake Module (ITBM), the “Trailer Brake Status
Indicator Light” will flash. GAIN Adjustment Buttons (+/-)
Pressing these buttons will adjust the brake control
power output to the trailer brakes in 0.5 increments. The
GAIN setting can be increased to a maximum of 10 or
decreased to a minimum of 0 (no trailer braking).
GAIN
The GAIN setting is used to set the trailer brake control
for the specific towing condition and should be changed
as towing conditions change. Changes to towing condi-
tions include trailer load, vehicle load, road conditions
and weather.
Adjusting GAIN
NOTE: This should only be performed in a traffic free
environment at speeds of approximately 20–25 mph
(30–40 km/h).336 STARTING AND OPERATING