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NOTE: Door Open Warning Light will differ depending
on the equipped instrument cluster display
Yellow Telltale Indicator Lights
Engine Check/Malfunction Indicator Light (MIL)
Yellow Telltale
Light What It Means
Engine Check/Malfunction Indicator Light (MIL)
The Engine Check/Malfunction Indicator Light (MIL) is a part of an Onboard Diagnostic
System called OBD II that monitors engine and automatic transmission control systems. The
light will illuminate when the ignition is in the ON position before engine start. If the bulb
does not come on when turning the key from OFF to ON/RUN, have the condition checked
promptly.
Certain conditions, such as a loose or missing gas cap, poor quality fuel, etc., may illuminate
the light after engine start. The vehicle should be serviced if the light stays on through sev-
eral typical driving styles. In most situations, the vehicle will drive normally and will not
require towing.250 UNDERSTANDING YOUR INSTRUMENT PANEL
Page 253 of 675
Yellow Telltale
Light What It Means
When the engine is running, the MIL may flash to alert serious conditions that could lead to
immediate loss of power or severe catalytic converter damage. The vehicle should be ser-
viced as soon as possible if this occurs.
CAUTION!Prolonged driving with the Malfunction Indicator
Light (MIL) on could cause damage to the engine
control system. It also could affect fuel economy and
driveability. If the MIL is flashing, severe catalytic
converter damage and power loss will soon occur.
Immediate service is required. WARNING!A malfunctioning catalytic converter, as referenced
above, can reach higher temperatures than in normal
operating conditions. This can cause a fire if you
drive slowly or park over flammable substances such
as dry plants, wood, cardboard, etc. This could result
in death or serious injury to the driver, occupants or
others. 4UNDERSTANDING YOUR INSTRUMENT PANEL 251
Page 264 of 675
Service 4WD Indicator Light — If Equipped
Yellow Telltale
Light What It Means
Service 4WD Indicator Light
If the light stays on or comes on during driving, it means that the 4WD system is not func-
tioning properly and that service is required. We recommend you drive to the nearest ser-
vice center and have the vehicle serviced immediately.
4 Low Indicator Light — If Equipped
Yellow Telltale
Light What It Means
4 Low Indicator Light
This light alerts the driver that the vehicle is in the four-wheel drive LOW mode. The front and
rear driveshafts are mechanically locked together forcing the front and rear wheels to rotate at the
same speed. Low range provides a greater gear reduction ratio to provide increased torque at the
wheels.
Refer to “Four-Wheel Drive Operation — If Equipped” in “Starting And Operating” for fur-
ther information on four-wheel drive operation and proper use.262 UNDERSTANDING YOUR INSTRUMENT PANEL
Page 276 of 675
NOTE: If the indicator message illuminates when you
start the vehicle, the oil change indicator system did not
reset. If necessary, repeat this procedure.
EVIC Messages
• Front Seatbelts Unbuckled
• Driver Seatbelt Unbuckled
• Passenger Seatbelt Unbuckled
• Service Airbag System
• Traction Control Off
• Washer Fluid Low
• Oil Pressure Low
• Oil Change Due
• Fuel Low
• Service Antilock Brake System • Service Electronic Throttle Control
• Service Power Steering
• Cruise Off
• Cruise Ready
• Cruise Set To XXX MPH
• Tire Pressure Screen With Low Tire(s) “Inflate Tire to
XX”
• Tire Pressure Information System (TPIS)
• Service Tire Pressure System
• Parking Brake Engaged
• Brake Fluid Low
• Service Electronic Braking System
• Engine Temperature Hot274 UNDERSTANDING YOUR INSTRUMENT PANEL
Page 296 of 675
NOTE: If the indicator message illuminates when you
start the vehicle, the oil change indicator system did not
reset. If necessary, repeat this procedure.
DID Messages
• Front Seatbelts Unbuckled
• Driver Seatbelt Unbuckled
• Passenger Seatbelt Unbuckled
• Service Airbag System
• Traction Control Off
• Washer Fluid Low
• Oil Pressure Low
• Oil Change Due
• Fuel Low
• Service Antilock Brake System • Service Electronic Throttle Control
• Service Power Steering
• Cruise Off
• Cruise Ready
• Cruise Set To XXX MPH
• Tire Pressure Screen With Low Tire(s) “Inflate Tire to
XX”
• Tire Pressure Information System (TPIS)
• Service Tire Pressure System
• Parking Brake Engaged
• Brake Fluid Low
• Service Electronic Braking System
• Engine Temperature Hot294 UNDERSTANDING YOUR INSTRUMENT PANEL
Page 417 of 675

conditions may be reduced. 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. 5STARTING AND OPERATING 415
Page 431 of 675

3. When the shift is complete, the indicator light for the
selected 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 not shift.
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. 5STARTING AND OPERATING 429
Page 483 of 675
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 (1.6 mm). When the tread is worn 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 replace-
ment.
• Distance driven.
• Performance tires, tires with a speed rating of V or
higher, and Summer tires typically have a reducedTire Tread1—WornTire
2—NewTire
5STARTING AND OPERATING 481