Starting Your Engine
1. Turn your ignition key to RUN.
Observe the wait to start light. SeeWait to Start
Indicator on page 3-36. 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 your 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 plug system.
Notice:Holding your key in START for longer than
15 seconds at a time will cause your battery to
be drained much sooner. And the excessive heat
can damage your starter motor.Notice:If the wait to start light stays on after
starting your vehicle, your vehicle may not run
properly. Have your 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 your engine after you have run
out of fuel, seeRunning Out of Fuel on page 5-17.
When your engine is cold, let it run for a few minutes
before you move your vehicle. This lets oil pressure
build up. Your 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 your vehicle. Do not let your engine run
when you are not in your vehicle.
2-15
Cold Weather Starting
If your vehicle has the 6.6L DURAMAX®Diesel Engine
and the Isuzu 6H Diesel Engine, the following notice
applies:
Notice:Your 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 uid 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 uid or you could
damage your engine. If you have the GM system,
use only GM approved starting uid that has
been tested to establish compatibility with the air
inlet heater system.
The following tips will help you get good starting in cold
weather.
•Use the recommended engine oil when the outside
temperature drops below freezing. SeeEngine Oil
(Caterpillar
®Diesel Engine) on page 5-23or
Engine Oil (Gasoline Engine) on page 5-24or
Engine Oil (DURAMAX
®Diesel Engine) on
page 5-28orEngine Oil (Isuzu Diesel Engine) on
page 5-32. When the outside temperature drops
below 0°F (−18°C), use of the optional engine
coolant block 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 your optional engine coolant block heater.
SeeEngine Coolant Heater on page 2-25.
•SeeWhat Fuel to Use on page 5-9for information
on what fuel to use in cold weather.
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 and use of the proper
engine oil, optional engine coolant heaters and optional
ether injection systems 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, you will first have to shift to NEUTRAL (N). This
safety feature prevents starting the engine when the
transmission is in a drive gear for more information.
2-16
If the light does not come on when the engine is cold,
your vehicle needs service.
If your batteries do not have enough charge to start
your engine, seeBattery on page 5-66.
Be sure you have the right oil for your engine, and that
you have changed the oil at the proper times. If you
use the wrong oil, your engine may be harder to start.
Be sure you are using the proper fuel for existing
weather conditions. SeeWhat Fuel to Use on page 5-9.
If the engine starts, runs a short time, then stops,
your vehicle needs service.
{CAUTION:
Do not use gasoline or starting aids, such as
ether, in the air intake. They could damage
your engine. There could also be a re, which
could cause serious personal injury.
Engine Alarm and Automatic
Shutdown
Your check gages warning light will come on if the
system senses high engine temperature, and a low or
high engine oil pressure. If high engine temperature
is detected, you will hear a tone alarm at two beats per
second. If a low or high engine oil pressure is
detected, you will also hear a tone alarm at two beats
per second. The alarm and the light will remain on until
the condition is fixed. If the engine temperature or oil
pressure condition worsens, the tone alarm will go to
five beats per second.
If the system senses low engine coolant, the five beat
per second alarm and the low coolant warning light
will come on.
The five beats per second tone alarm means that your
engine will shut down in about 25 to 30 seconds.
There is also an engine shutdown light to indicate that
the engine will shut down. SeeEngine Shutdown
Warning Light on page 3-39.
2-18
Pull off the road and shut off the engine. Do not start it
until the reason for the problem is known, and the
problem is fixed. If the engine shuts down when you are
still in traffic, you can restart the engine and get another
25 to 30 seconds of operation. Do this only if you have to,
since there is a problem that can harm the engine if it is
not fixed. Engine automatic shutdown, for gasoline
engines, requires activation by your dealer/retailer.
Notice:If you try to operate the vehicle after the
engine automatically shuts down, you may damage
the vehicle. Have your vehicle repaired as soon
as possible.
Ambulance, Fire, and Rescue Packages
Your check gages warning light will come on if the
system senses high engine temperature or low engine
oil pressure. If high engine temperature or low engine oil
pressure is detected, you will also hear a tone alarm
at two beats per second. The alarm and the light
will remain on until the condition is fixed. If the engine
temperature or oil pressure condition worsens, the
tone alarm will go to five beats per second.
If the system senses low engine coolant, the five beat
per second alarm and the low coolant warning light
will come on.
The engine will not shutdown, but you should have the
vehicle checked as soon as you can. SeeCheck
Gages Warning Light on page 3-42for more information.
Idle Shutdown
If your vehicle has a diesel engine it could have an
engine idle shutdown feature.
This feature automatically shuts down the engine after it
idles continuously for five minutes and if the following
conditions are met:
•The parking brake is set.
•The vehicle is at a complete stop.
•The automatic transmission is in NEUTRAL (N) or
PARK (P).
If the parking brake is not engaged, then the engine
shuts down after 15 minutes of continuous idling
operation.
The driver can reset the engine shutdown timer by
momentarily changing the position of the accelerator,
brake, or clutch pedal or by shifting the transmission out
of PARK (P) or NEUTRAL (N). Once reset, the engine
idle shutdown will restart the shutdown sequence
described above, and will continue to do so until the
engine shuts down or the vehicle is driven.
2-19
During this warm-up period, check your warning lights
and gages:
•If oil pressure does not begin to rise within
15 seconds of starting, stop the engine and find the
cause. SeeOil Pressure Gage on page 3-37for
more information.
•If the engine coolant temperature gage needle goes
into the hot area on the gage, stop the engine and
find the cause of the overheating. SeeEngine
Coolant Temperature Gage on page 3-35for more
information.
•If you have air brakes, the dual-needle air pressure
gage should read at least 115 psi (790 kPa) for both
service systems before you try to move the vehicle.
When air pressure is below 60 psi (420 kPa), the
LOW AIR light will come on and you will hear a tone
alarm. SeeBrake System Warning Light on
page 3-32for more information. If the pressure does
not build up or drops during warm-up, stop the
engine and find the cause before you try to move the
vehicle. Recommended air pressure before driving is
120 psi (830 kPa). SeeAir Pressure Gage on
page 3-46for more information.
•The charging system light should come on when the
ignition key is turned to ON/RUN or START and
should go out when the engine is running above idle.
If the light does not go out or comes back on during
normal engine operation, have the charging system
checked right away. (This light tells you if the
generator is not charging; it does not reflect the
condition of the battery.) SeeCharging System Light
on page 3-30for more information.
•The voltmeter charge indicator gage tells you the
condition of your battery’s charge. The gage should
be in the center area during engine operation. The
red area on the left indicates an undercharge
condition; the red area on the right indicates an
overcharge. If the gage is in either red area, have the
battery and charging system checked right away.
SeeVoltmeter Gage on page 3-31for more
information.
Notice:Do not allow the engine to operate at low
idle for more than ve minutes. This can cause
low engine operating temperatures which can affect
engine operation and reduce engine life. Engine
idle speed should be increased to 1200 rpm
whenever extended idle is required. Once started,
the engine should be placed under load to allow the
engine coolant temperature to reach 150°F (66°C)
before shutting off the engine.
2-24
Engine Coolant Heater
The engine coolant heater, if available, can help in cold
weather conditions at or below 0°F (−18°C) for easier
starting and better fuel economy during engine warm-up.
Plug in the coolant heater at least four hours before
starting your vehicle.
To Use the Engine Coolant Heater
1. Turn off the engine.
2. Find the plug-in outlet located under the
driver’s door.
3. Plug it into a normal, grounded 110-volt AC outlet.
{CAUTION:
Plugging the cord into an ungrounded outlet
could cause an electrical shock. Also, the
wrong kind of extension cord could overheat
and cause a re. You could be seriously
injured. Plug the cord into a properly grounded
three-prong 110-volt AC outlet. If the cord will
not reach, use a heavy-duty three-prong
extension cord rated for at least 15 amps.
4. Before starting the engine, be sure to unplug and
store the cord as it was before to keep it away
from moving engine parts. If you do not, it could be
damaged.
How long should you keep the coolant heater plugged
in? The answer depends on the outside temperature, the
kind of oil you have, and some other things. Instead
of trying to list everything here, we ask that you contact
your dealer/retailer in the area where you will be
parking your vehicle. The dealer/retailer can give you
the best advice for that particular area.
2-25
Diesel Particulate Filter (Diesel
Engine)
Your vehicle has a Diesel Particulate Filter (DPF) as
part of the exhaust system to reduce vehicle emissions.
The DPF requires a unique exhaust tailpipe with an
exhaust cooler. The exhaust cooler mixes air with the
exhaust at the tailpipe. This lowers the exhaust
temperature before it leaves the tailpipe.
The DPF, the tailpipe, or other exhaust system
components must not be altered. The area where the
exhaust cooler connects to the tailpipe should be
inspected, especially the area where the fresh air enters
the cooler. Make sure the openings are not restricted
or plugged with mud or dirt which could inhibit exhaust
gas cooling. See “Exhaust System Inspection” under
At Least Twice a Year on page 6-27.The DPF will regenerate (self-clean) itself as part of
normal operation. During regeneration, the green DPF
indicator is lit and you will notice a difference in
engine noise and engine speed, but this is normal. The
Engine Control Module (ECM) controls this function
based on several factors including the amount of fuel
consumed, hours of engine operation and miles driven.
Notice:Use of diesel fuel other than Ultra Low
Sulfur Diesel (15 ppm sulfur maximum) or engine oil
other than low ash CJ-4 oil will cause permanent
damage to the DPF and related components.
This damage would not be covered by your
warranty.
Your DPF equipped vehicle has specific fuel and engine
oil requirements. SeeWhat Fuel to Use on page 5-9
andEngine Oil (Caterpillar
®Diesel Engine) on
page 5-23orEngine Oil (Gasoline Engine) on page 5-24
orEngine Oil (DURAMAX
®Diesel Engine) on page 5-28
orEngine Oil (Isuzu Diesel Engine) on page 5-32to
make sure you use the required fuel and engine oil.
2-46
For vehicles with Power Take-Off (PTO), monitor the
instrument panel cluster for lights related to the DPF.
All engines consume some amount of engine oil. This is
normal. The by-product of combustion of engine oil is
ash. The ash will become trapped in the DPF over
the life of the vehicle. Eventually, the buildup of ash will
restrict the exhaust gases and the DPF will need to
be cleaned or replaced.
SeeAccessories and Modifications on page 5-4for
important information.
Manual Regeneration Procedure
{CAUTION:
During DPF regeneration, the exhaust system
and exhaust gases are very hot. Stay clear of
the tailpipe area and do not park over things
that burn. You or others could be burned or
your vehicle could catch re. SeeParking Over
Things That Burn on page 2-44.If the yellow or red DPF indicator is on, you can clean
the DPF by performing a manual regeneration.
When it is safe to do so, stop the vehicle. Perform
manual DPF regeneration in a well ventilated area.
Manual DPF regeneration must be performed outdoors,
as follows. Once manual regeneration is started,
complete the regeneration in a single operation if
possible. If manual regeneration is not completed, as
indicated by the green DPF indicator going off, and the
yellow or red indicator light remains on, automatic
regeneration might not be allowed until the vehicle is
stopped and manual regeneration is performed
until completed.
1. Check engine oil and engine coolant levels to be
sure they are at proper operating levels.
2. To prevent running out of fuel during regeneration,
make sure there is at least a quarter of a tank
of fuel.
3. Check to make sure the area near the exhaust
tailpipe and under the exhaust system are clear
of any materials that could catch fire. Keep people
away from the area of the exhaust system and
exhaust gases.
2-48