
Starting the Engine
1. Without pushing the accelerator pedal, turn the
ignition key to START. When the engine starts,
let go of the key. The idle speed will go down as the
engine gets warm.
2. If the engine does not start in 10 seconds, push the
accelerator pedal all the way down and crank the
engine for five more seconds, unless it starts sooner.
3. If the engine still will not start, or starts but then
stops, it could be flooded with too much gasoline.
Wait 15 seconds to let the starter motor cool down.
Do Steps 1 through 3 again.
When the engine starts, let go of the key and the
accelerator pedal.
Notice:The engine is designed to work with the
electronics in the vehicle. If you add electrical parts
or accessories, you could change the way the
engine operates. Before adding electrical equipment,
check with your dealer/retailer. If you do not, the
engine might not perform properly. Any resulting
damage would not be covered by the vehicle
warranty.
If you ever need to have the vehicle towed, seeTowing
Your Vehicle on page 4-23.
Gasoline Engine Warm-Up
When the engine starts, let it run for 20 or 30 seconds
to warm up before putting a load on it.
Drive at moderate speeds for the first 2 to 3 miles
(3.2 to 4.8 km), especially in cold weather. SeeHigh
Idle System on page 2-20.
Restarting the Gasoline Engine While
Moving (Automatic Transmission)
If you have to restart the engine while the vehicle is
moving, shift to N (Neutral).
Stopping the Gasoline Engine
Let the engine idle for a few seconds before turning it
off after you have finished driving the vehicle.
If you shift to N (Neutral) or P (Park), set the parking
brake.
If the vehicle has a two-speed axle, put the range
selector in low. To be sure the axle has shifted into low,
engage the clutch and transmission; the vehicle may
move slightly when you do this.
While the engine is idling and before you turn it off, you
can make a list of any operational or handling concerns to
give to responsible maintenance personnel so they can
handle them right away.
2-13

Moisture will condense in a fuel tank that is almost
empty if the engine has not run for a while, even just
overnight under some conditions. So, it is always best to
refuel the vehicle at the end of each run.
Starting the Diesel Engine
The vehicle’s diesel engine starts differently than a
gasoline engine. Read the following pages to learn how
to start, restart, warm-up, and stop the diesel engine.
The information applies to Caterpillar
®Diesel Engine,
6.6L DURAMAX®Diesel Engine, Isuzu 6H Diesel
Engine, unless otherwise noted.
If you have a Caterpillar
®Diesel Engine, also refer to
the Caterpillar®Diesel Engine Operation & Maintenance
Manual for the starting procedure.
Automatic Transmission
Move the shifter to P (Park) or N (Neutral). The engine
will not start in any other position. To restart the
engine when the vehicle is already moving, use
N (Neutral) only.
Notice:Do not try to shift to P (Park) if the
vehicle is moving. If you do, you could damage
the transmission. Shift to P (Park) only when
the vehicle is stopped.
Manual Transmission
Move the shift lever to N (Neutral) and hold the clutch
pedal to the floor while starting the engine. The vehicle
will not start if the clutch pedal is not all the way down.
Starting the Engine
1. Turn your ignition key to ON/RUN.
Observe the wait to start light. SeeWait to Start
Light on page 3-35. This light may not come
on if the engine is hot.
If you have a Caterpillar
®diesel engine, see your
Caterpillar®Diesel Engine Operation & Maintenance
Manual for proper wait to start light operation.
2. As soon as the wait to start light goes off,
immediately turn the ignition key to START.
When the engine starts, let go of the key.
If the vehicle is equipped with a DURAMAX
®
6600 Diesel Engine, it has a fast warm-up glow
plug system. The wait to start light will illuminate for
a much shorter time than most diesel engines,
due to the rapid heating of the glow plugs.
Notice:Holding the key in START for longer than
15 seconds at a time will cause the battery to
be drained much sooner. And the excessive heat
can damage the starter motor.
2-14

Notice:If the wait to start light stays on after
starting the vehicle, the vehicle may not run
properly. Have the vehicle serviced right away.
3. If the engine does not start after 15 seconds
of cranking, turn the ignition key to OFF. Wait one
minute for the starter to cool, then try the same
steps again.
If you are trying to start the engine after you have run
out of fuel, seeRunning Out of Fuel on page 5-17.
When the engine is cold, let it run for a few minutes
before you move the vehicle. This lets oil pressure build
up. The engine will sound louder when it is cold.
Notice:If you are not in an idling vehicle and the
engine overheats, you would not be there to see the
overheated engine indication. This could damage
the vehicle. Do not let the engine run when you are
not in the vehicle.
Cold Weather Starting
If the vehicle has the 6.6L DURAMAX®Diesel Engine or
the Isuzu 6H Diesel Engine, the following notice applies:
Notice:The diesel engine has an electric air intake
heater system which reduces white smoke and
helps start the engine in cold weather. Do not spray
starting fluid into the air intake where it can
contact the heater elements.If you do not have the GM Automatic Ether Injection
System, do not use starting fluid or you could
damage the engine. If you have the GM system, use
only GM approved starting fluid that has been tested
to establish compatibility with the air inlet heater
system.
The following tips will help with engine starting in cold
weather.
•Use the recommended engine oil when the outside
temperature drops below freezing. SeeEngine Oil
(DURAMAX Diesel Engine) on page 5-24or
Engine Oil (Caterpillar Diesel Engine) on page 5-27
orEngine Oil (Isuzu Diesel Engine) on page 5-28
orEngine Oil (Gasoline Engine) on page 5-32.
When the outside temperature drops below
0°F (−18°C), use of the optional engine coolant
heater is recommended.
•If you experience longer cranking times, notice an
unusual amount of exhaust smoke or are at
higher altitudes (over 7,000 ft. or 2 135 m), you may
use the optional engine coolant heater. See
Engine Coolant Heater on page 2-25.
•SeeWhat Fuel to Use on page 5-8for information
on what fuel to use in cold weather.
2-15

Cold Weather Starting (Caterpillar®
Diesel)
Because the diesel engine uses compression ignition, it
is harder to start in cold weather than a gasoline engine.
The air intake heater, use of the proper engine oil,
optional engine coolant heater and optional ether
injection system help cold weather starting. See the
Caterpillar
®Diesel Engine Operation & Maintenance
Manual for more information.
Restarting the Diesel Engine While
Moving (Automatic Transmission)
If you have to restart the engine while the vehicle is
moving, shift to N (Neutral).
Stopping the Diesel Engine
1. Apply the parking brake. SeeParking Brake (With
Hydraulic Brakes) on page 2-38orParking Brake
(With Air Brakes) on page 2-41for parking
brake apply procedure.
2. Shift into N (Neutral) for a manual transmission or
P (Park) for an automatic transmission.3. Turn the ignition key to OFF.
If the vehicle has a two-speed axle, seeTwo-Speed
Rear Axle on page 2-36.
If you have a Caterpillar
®diesel engine, see the
Caterpillar®Diesel Engine Operation & Maintenance
Manual for additional information.
Diesel Engine Warm-Up
Several factors affect how quickly the diesel engine
warms up. These can include outside temperature,
engine load, idle time and the vehicle’s option content.
The vehicle may be equipped with some features
that can help the engine reach operating temperature
sooner. Some of these features are discussed below.
Also, remember that an automatic transmission
adds heat to the cooling system through the heat
exchanger in the radiator. Because of this, vehicles
equipped with automatic transmissions are often able to
retain engine coolant heat better than manual
transmission vehicles.
See the Caterpillar
®Operation & Maintenance manual
for additional diesel engine warm-up information.
2-16

If the Diesel Engine Will Not Start
If you have run out of fuel, seeRunning Out of Fuel on
page 5-17.
If you are not out of fuel, and the engine will not start,
do this:
Turn the ignition key to ON/RUN. Immediately after the
wait to start light goes off, turn the ignition key to START.
If the light does not go off, wait a few seconds, then try
starting the engine again. And, see your dealer/retailer
as soon as you can for a starting system check.
If the light comes on and then goes off and you know
the batteries are charged, but the engine still will
not start, the vehicle needs service.
If the light does not come on when the engine is cold,
the vehicle needs service.If the batteries do not have enough charge to start the
engine, seeBattery on page 5-61.
Be sure you have the right oil for the engine, and that
you have changed the oil at the proper times. If you use
the wrong oil, the engine may be harder to start.
Be sure you are using the proper fuel for existing
weather conditions. SeeWhat Fuel to Use on page 5-8.
If the engine starts, runs a short time, then stops, the
vehicle needs service.
{CAUTION:
Do not use gasoline or starting aids, such as
ether, in the air intake. They could damage the
engine. There could also be a fire, which could
cause serious personal injury.
2-17

The ENGINE SHUTDOWN WARNING LIGHT will come
on and a continuous chime will alert the driver
30 seconds before the engine goes into idle shutdown
mode. The engine shutdown warning light and chime will
stay on for the entire duration of the idle shutdown
event to inform the driver that the engine is in idle
shutdown mode. SeeEngine Shutdown Warning Light
on page 3-40for more information.
After the engine shutdown occurs, the engine is no
longer running, and the ignition is still in the ON/RUN
position, all accessories can be used. Turn the ignition
switch to START to restart the engine or turn it to
LOCK or OFF to prevent the battery from draining.High Idle System
High Idle System with Switch
If the vehicle has this
feature, the manual high
idle switch is located in the
instrument panel
switchbank.
2-20

This system can be used to increase the engine idle
speed whenever the following conditions are met:
•The brake pedal is not pressed.
•The vehicle is at a complete stop for vehicles with
diesel engines. The vehicle must not be moving
and the accelerator must not be pressed for vehicles
with gasoline engines.
•If the vehicle has manual transmission the clutch
pedal is not pressed or, if the vehicle has the
automatic transmission it is in N (Neutral) or
P (Park).
The manual high idle feature is activated by pressing
the switch on the instrument panel. When the switch is
pressed again, or any of the previous conditions are
not met, manual high idle will be deactivated.
The manual high idle has been preset at the factory.
Your dealer/retailer may change the setting to fit
your needs.
For vehicles with Caterpillar
®diesel engines, the high
idle switch can be used to set any desired high idle
speed.To set a new temporary engine idle speed do the
following:
1. Make sure all of the previously described conditions
are met.
2. Press the accelerator pedal to the desired engine
speed.
3. Momentarily press the manual high idle switch.
The temporary high idle speed will be set. This new high
idle rpm level will be remembered by the system until
either the ignition is turned to OFF or a new high
idle speed is set.
Automatic High Idle System
The automatic high idle feature will engage whenever
you start the vehicle and the engine is below the preset
operating temperature. This will help decrease engine
warm-up time.
On vehicles that have the Caterpillar
®diesel engine you
may have an exhaust restrictor that will operate in
High Idle mode. The exhaust brake switch must be on
for this feature to operate. SeeDiesel Engine Exhaust
Brake on page 2-26for more information.
Idle speed will then return to normal when the engine
reaches the preset operating temperature or has
been operating for at least 10 minutes.
2-21

Exhaust Restrictor (Engine
Warm-Up)
Exhaust Restrictor
If the vehicle has a Isuzu 6H Diesel Engine, it may have
a feature called an Exhaust Restrictor (NPE), which
uses an air actuated valve in the exhaust system
to restrict exhaust gas flow which enhances the engine
and heater warm-up.
Automatic Quick Warm-Up
If the vehicle has a DURAMAX®6600 engine, it has a
feature called an Automatic Quick Warm-Up, which uses
the turbocharger to restrict the exhaust gas flow
which enhances the engine and heater warm-up.
In both systems, exhaust restrictor or automatic quick
warm-up, the cold temperature high idle feature elevates
the engines idle speed, up to 1500 rpm, and restricts
the exhaust gas flow, when outside temperatures
are below 50°F (10°C), and the engine coolant
temperature is below certain levels. This feature
enhances heater performance by raising the engine
coolant temperature faster.For all engines this feature is already turned on. The
automatic quick warm-up on the DURAMAX
®engine
can be turned off and on by doing the following
procedure:
1. Turn the ignition to ON/RUN, with the vehicle off.
2. Press the accelerator pedal to the floor and
hold it while quickly pressing and fully releasing the
brake pedal three times in less than eight seconds.
3. Release the accelerator pedal and start the engine.
The green exhaust brake/restrictor light below the
radio controls will be lit for 10 seconds.
If this feature is turned off, by doing the procedure
described previously, and then the engine is
started, the exhaust brake/restrictor light will flash
for 10 seconds and then it will turn off.
When the engine is started, it will slowly increase to the
high idle speed after a delay of a few seconds; up to
about two minutes. For this method to work properly
there must be no throttle or brake pedal faults, and the
throttle pedal must not fall below 75 percent of wide
open throttle while pressing the brake pedal.
2-22