If the light remains lit with the engine running, your
vehicle will usually be drivable. However, see an autho-
rized dealer for service as soon as possible. If the light is
flashing when the engine is running, immediate service is
required. You may experience reduced performance, an
elevated/rough idle or engine stall and your vehicle may
require towing.
•Engine Temperature Warning Light
This light warns of an overheated engine condi-
tion. As temperatures rise and the gauge ap-
proaches H,this indicator will illuminate and a single
chime will sound after reaching a set threshold. Further
overheating will cause the temperature gauge to pass H,
a continuous chime will occur until the engine is allowed
to cool.
If the light turns on while driving, safely pull over and
stop the vehicle. If the A/C system is on, turn it off. Also, shift the transmission into NEUTRAL and idle the ve-
hicle. If the temperature reading does not return to
normal, turn the engine off immediately and call for
service. Refer to “If Your Engine Overheats” in “What To
Do In Emergencies” for more information.
•
Trailer Brake Disconnected Warning Light
This telltale is on when the Trailer Brake has
been disconnected.
DID Yellow Telltales
This area will show reconfigurable yellow caution tell-
tales. These telltales include:
•Low Fuel Telltale
When the fuel level reaches approximately 3.0 gal
(11.0 L), this light will turn on, and remain on until
fuel is added.
248 UNDERSTANDING YOUR INSTRUMENT PANEL
In all cases, normal operation will resume once the
transmission temperature has risen to a suitable level.
Transmission Limp Home Mode
Transmission function is monitored electronically for
abnormal conditions. If a condition is detected that could
result in transmission damage, Transmission Limp Home
Mode is activated. In this mode, the transmission remains
in fourth gear (for 66RFE transmission) or third gear (for
AS66RC transmission) regardless of which forward gear
is selected. If an AS66RC equipped truck enters Limp
Home Mode at highway speeds, it will initially engage
fifth gear, until the vehicle slows to a speed where third
gear can be engaged. PARK, REVERSE, and NEUTRAL
will continue to operate. The Malfunction Indicator Light
(MIL) may be illuminated. Limp Home Mode allows the
vehicle to be driven to an authorized dealer for service
without damaging the transmission.In the event of a momentary problem, the transmission
can be reset to regain all forward gears by performing the
following steps:
1. Stop the vehicle.
2. Shift the transmission into PARK.
3. Turn the ignition switch to the OFF position.
4. Wait approximately 10 seconds.
5. Restart the engine.
6. Shift into the desired gear range. If the problem is no
longer detected, the transmission will return to normal
operation.
NOTE: Even if the transmission can be reset, we recom-
mend that you visit your authorized dealer at your
earliest possible convenience. Your authorized dealer has
diagnostic equipment to determine if the problem could
recur.
5
STARTING AND OPERATING 343
3. When the shift is complete, the indicator light for theselected position will stop flashing and remain ON.
If One Or More Shift Conditions Are Not Met:
1. The indicator light for the current position will remain ON.
2. The newly selected position indicator light will con- tinue to flash.
3. The transfer case will notshift.
NOTE: Before retrying a selection, make certain that all
the necessary requirements for selecting a new transfer
case position have been met. To retry the selection, turn
the control knob back to the current position, wait five
seconds, and retry selection. To find the shift require-
ments, refer to the Shifting Procedure for your transfer
case, located in this section. The “SVC 4WD Warning Light” monitors the electronic
shift four-wheel drive system. If this light remains on
after engine start up or illuminates during driving, it
means that the four-wheel drive system is not function-
ing properly and that service is required.
WARNING!
Always engage the parking brake when powering
down the vehicle if the “SVC 4WD Warning Light” is
illuminated. Not engaging the parking brake may
allow the vehicle to roll, which may cause personal
injury.
NOTE: Do not attempt to make a shift while only the
front or rear wheels are spinning, as this can cause
damage to driveline components.
When operating your vehicle in 4WD LOW, the engine
speed is approximately three times that of the 2WD or5
STARTING AND OPERATING 357
These indicators are molded into the bottom of the tread
grooves. They will appear as bands when the tread depth
becomes a 1/16 of an inch (2 mm). When the tread isworn to the tread wear indicators, the tire should be
replaced. Refer to “Replacement Tires” in this section for
further information.
Life Of Tire
The service life of a tire is dependent upon varying
factors including, but not limited to:
•
Driving style.
•
Tire pressure - Improper cold tire inflation pressures can
cause uneven wear patterns to develop across the tire
tread. These abnormal wear patterns will reduce tread
life, resulting in the need for earlier tire replacement.
• Distance driven.
• Performance tires, tires with a speed rating of V or
higher, and summer tires typically have a reduced
tread life. Rotation of these tires per the vehicle main-
tenance schedule is highly recommended.
1—WornTire
2—NewTire 404 STARTING AND OPERATING
as hard starting, stalling, and hesitations. If you experi-
ence these symptoms, try another brand of gasoline
before considering service for the vehicle.
Over 40 auto manufacturer’s world wide have issued and
endorsed consistent gasoline specifications (the World-
wide Fuel Charter, WWFC) which define fuel properties
necessary to deliver enhanced emissions, performance,
and durability for your vehicle. The manufacturer recom-
mends the use of gasolines that meet the WWFC speci-
fications, if they are available.
Reformulated Gasoline
Many areas of the country require the use of cleaner
burning gasoline referred to as “Reformulated Gasoline.”
Reformulated gasoline contain oxygenates and are spe-
cifically blended to reduce vehicle emissions and im-
prove air quality.The manufacturer supports the use of reformulated gaso-
line. Properly blended reformulated gasoline will pro-
vide excellent performance and durability of engine and
fuel system components.
Gasoline/Oxygenate Blends
Some fuel suppliers blend unleaded gasoline with oxy-
genates such as Ethanol.
CAUTION!
DO NOT use gasoline containing Methanol or gaso-
line containing more than 10% Ethanol. Use of these
blends may result in starting and drivability prob-
lems, damage critical fuel system components, cause
emissions to exceed the applicable standard, and/or
cause the “Malfunction Indicator Light” to illumi-
nate. Pump labels should clearly communicate if a
fuel contains greater than 10% Ethanol.
422 STARTING AND OPERATING
ONBOARD DIAGNOSTIC SYSTEM (OBD II)
Your vehicle is equipped with a sophisticated onboard
diagnostic system called OBD II. This system monitors
the performance of the emissions, engine, and automatic
transmission control systems. When these systems are
operating properly, your vehicle will provide excellent
performance and fuel economy, as well as engine emis-
sions well within current government regulations.
If any of these systems require service, the OBD II system
will turn on the “Malfunction Indicator Light (MIL).” It
will also store diagnostic codes and other information to
assist your service technician in making repairs. Al-
though your vehicle will usually be drivable and not
need towing, see your authorized dealer for service as
soon as possible.
CAUTION!
•Prolonged driving with the MIL on could cause
further damage to the emission control system. It
could also affect fuel economy and driveability.
The vehicle must be serviced before any emissions
tests can be performed.
• If the MIL is flashing, while the engine is running,
severe catalytic converter damage and power loss
will soon occur. Immediate service is required.
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/DID telltale display
area. Refer to “Electronic Vehicle Information Center
7
MAINTAINING YOUR VEHICLE 489
(EVIC)” or “Driver Information Display (DID)” in “Un-
derstanding Your Instrument Panel” for further informa-
tion. 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.
A loose, improperly installed, or damaged fuel filler cap
may also turn on the Malfunction Indicator Light (MIL).
EMISSIONS INSPECTION AND MAINTENANCE
PROGRAMS
In some localities, it may be a legal requirement to pass
an inspection of your vehicle’s emissions control system.
Failure to pass could prevent vehicle registration.For states that require an Inspection and Mainte-
nance (I/M), this check verifies the “Malfunction
Indicator Light (MIL)” is functioning and is not
on when the engine is running, and that the OBD II
system is ready for testing. Normally, the OBD II system will be ready. The OBD II
system may
notbe ready if your vehicle was recently
serviced, recently had a dead battery or a battery replace-
ment. If the OBD II system should be determined not
ready for the I/M test, your vehicle may fail the test.
Your vehicle has a simple ignition actuated test, which
you can use prior to going to the test station. To check if
your vehicle’s OBD II system is ready, you must do the
following:
1. Cycle the ignition switch to the ON position, but do not crank or start the engine.
NOTE: If you crank or start the engine, you will have to
start this test over.
2. As soon as you cycle the ignition switch to the ON position, you will see the Malfunction Indicator Light
(MIL) symbol come on as part of a normal bulb check.
490 MAINTAINING YOUR VEHICLE
MAINTENANCE SCHEDULE
Your vehicle is equipped with an automatic oil change
indicator system. The oil change indicator system will
remind you that it is time to take your vehicle in for
scheduled maintenance.
Based on engine operation conditions, the oil change
indicator message will illuminate. This means that ser-
vice is required for your vehicle. Operating conditions
such as frequent short-trips, trailer tow, extremely hot or
cold ambient temperatures, and E85 fuel usage will
influence when the “Oil Change Required” message is
displayed. Severe Operating Conditions can cause the
change oil message to illuminate as early as 3,500 miles
(5,600 km) since last reset. Have your vehicle serviced as
soon as possible, within the next 500 miles (805 km).
Your authorized dealer will reset the oil change indicator
message after completing the scheduled oil change. If a
scheduled oil change is performed by someone other
than your authorized dealer, the message can be reset byreferring to the steps described under “Electronic Vehicle
Information Center (EVIC)/Driver Information Display
(DID)” in “Understanding Your Instrument Panel” for
further information.
NOTE:
•
Gasoline Engines
• Under no circumstances should oil change intervals
exceed 8,000 miles (13,000 km) or twelve months,
whichever comes first.
• Severe Duty
•
Change Engine Oil at 4000 miles (6,500 km) if the vehicle
is operated in a dusty and off road environment. This
type of vehicle use is considered Severe Duty
Once A Month Or Before A Long Trip:
• Check engine oil level
• Check windshield washer fluid level
560 MAINTENANCE SCHEDULES