Engine Checks Before Operating
When you have started your engine, let it run for
20 to 30 seconds before you put a load on the engine.
But do not leave the vehicle while the engine is running.
Avoid unnecessary idling of diesel engine equipped
vehicles.
If the engine idles too long, the temperature of the
engine coolant will fall below the normal operating
range. Low engine operating temperature causes
several conditions which affect engine operation and
reduce engine life.
The engine should be permitted to go through a
warm-up period. Operate the vehicle at a minimum
of 600 rpm during the warm-up period. During this period
and during operation, the following observations
should be made.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 3-38for
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 3-36for 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 3-33for 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 3-47for more information.
2-24
Diesel Engine Exhaust Brake
If your vehicle has a DURAMAX®7800 or Caterpillar®
diesel engine, it may have an exhaust brake, which
is located in the exhaust system.
If your vehicle has a 6.6L DURAMAX
®6600 diesel
engine, it may have an exhaust brake, which is
controlled through the turbocharger.
The exhaust brake for both engines operates the same.
The exhaust brake switch
is located in the instrument
panel switchbank.
Push the bottom of the switch to turn the exhaust brake
on. When you push the top of the switch, the exhaust
brake will turn off.
There is an indicator light on the instrument panel
similar to the symbol on the switch, that will come on
when the exhaust brake is active. SeeExhaust
Brake Indicator Light on page 3-41for more information.When using the exhaust brake, the proper gear range
selection is important. The exhaust brake will be
most effective if the gear range selected is the lowest
possible range that does not allow the engine rpm to go
more than 200 rpm above rated (full load) rpm. If you
have a Caterpillar®diesel engine, do not exceed
2900 rpm. If you have a DURAMAX®7800 diesel
engine, do not exceed 2550 rpm. If you have a
DURAMAX
®6600 diesel engine, do not exceed
3600 rpm.
If your vehicle has an Allison
®1000/2200/2300/2500
series automatic transmission and press this button, the
transmission will downshift to a factory default setting
of third gear. To change the default setting, or for more
information on factory default settings, contact your
dealer for assistance.
The accelerator and clutch pedals must be released in
order for the exhaust brake to engage. The exhaust
brake will automatically shut off when the anti-lock brake
system is active.
If your vehicle has a Caterpillar
®diesel engine or a
DURAMAX®6600 diesel engine, the exhaust brake will
become active in cruise control when you exceed
the set speed by 3 to 5 mph.
2-27
Two-Speed Rear Axle Electric Shift
Control
If your vehicle has this feature, you will find a label on
the headliner above the windshield or in another
place near the driver that shows how to use it. Be sure
to follow the directions carefully.
Use the following directions based on the type of shift
control the vehicle has.
The rear axle shift control
switch for a manual
transmission is located on
the shift lever.
When the switch is down, the rear axle is in the high
range. When the switch is up the rear axle is in
low range. Push or pull the switch to change the range.The two-speed axle should be in the up position or low
range when you park the vehicle. You will need to
engage the transmission and move the vehicle a little to
assure the axle is in the low range. Then apply the
parking brake, shift into NEUTRAL and shut off
the engine.
Also, always start the vehicle in motion with the
two-speed axle in the low range.
To shift up from low to high, do the following:
1. Move the switch down for the high range.
2. Disengage the clutch.
3. After a brief pause, engage the clutch and then
press down on the accelerator pedal until the
axle engages.
To shift down from high to low, do the following:
1. Release the accelerator and pull the switch upward
for low range.
2. Press the accelerator pedal slowly until the axle
engages.
2-28
Air Shift Control
(Automatic Transmission)
The rear axle shift control
switch for an automatic
transmission is located in
the instrument panel
switchbank.
To use the rear axle shift control, press the bottom of
the switch to get to the high range. The switch indicator
light will come on when the vehicle is in the high
range. Press the top of the switch to return to the low
range.
The two-speed axle should be in low range when
you park the vehicle. You will need to engage the
transmission and move the vehicle a little to assure the
axle is in range. Then shift into PARK (P), apply the
parking brake, and shut off the engine.To shift up from low to high range while driving, press
the bottom of the rear axle shift control switch as you are
releasing the accelerator pedal. After the shift has
occurred, apply the accelerator as desired.
To shift from high to low range while driving, press the
top of the rear axle shift control switch as you release
the accelerator pedal. Press the accelerator pedal slowly
until the down shift has occurred, then apply the
accelerator as desired.
For better performance during off-road or under a heavy
load, shift the axle into low range and then operate
the transmission normally.
For better performance on the highway, shift the axle to
high range and operate the transmission normally.
2-29
Automatic Transmission Operation
We build vehicles with Allison®five and six-speed
automatic transmissions. This part of the manual covers
the basics of these. With these transmissions, you
will find another Allison
®manual in your vehicle that
goes into more detail. On the headliner, in front of and
above the driver, or in some other place near the
driver, you will see a label that describes important
operating facts about the automatic transmission in
your vehicle. Make sure you follow the instructions on
this label.
Be sure to keep your parking brake set until you are
ready to shift into DRIVE (D), and press the brake pedal
while shifting from NEUTRAL (N) or PARK (P) to a
drive gear.
All vehicles equipped with automatic transmissions can
be started in PARK (P), if equipped, or in NEUTRAL (N).
See the Allison
®Transmission Operator’s Manual in
your vehicle for more information about this.
{CAUTION:
It can be dangerous to get out of your vehicle
without the parking brake rmly set. Your
vehicle can roll. If you have left the engine
running, the vehicle can move suddenly. You
or others could be injured. To be sure your
vehicle will not move, even when you are on
fairly level ground, always set the parking
brake.
{CAUTION:
Shifting into a drive gear while your engine is
running at high speed is dangerous. Unless
your foot is rmly on the brake pedal, your
vehicle could move very rapidly. You could
lose control and hit people or objects. Do not
shift into a drive gear while your engine is
running at high speed.
2-30
FIRST (1):With the vehicle at a stop, release the
brake, press the clutch pedal and shift into FIRST (1).
Then, slowly let up on the clutch pedal as you press the
accelerator pedal. Only downshift into FIRST (1)
when the vehicle has come to a complete stop. If the
shift lever will not go into FIRST (1), put the lever
in NEUTRAL and let up on the clutch pedal to fully
engage the clutch. Press the clutch pedal again. Then,
shift into FIRST (1).
SECOND (2):With the vehicle at a stop, release the
brake, press the clutch pedal and shift into SECOND (2).
Then, slowly let up on the clutch pedal as you press
the accelerator pedal. With the vehicle moving, press
the clutch pedal and upshift into SECOND (2) from
FIRST (1) while applying light pressure to the right on
the shifter. Then, slowly let up on the clutch pedal
as you press the accelerator pedal. If you come to a
complete stop and the shift lever will not go into
SECOND (2), put the lever in NEUTRAL and let up on
the clutch pedal to fully engage the clutch. Press
the clutch pedal again. Then, shift into SECOND (2).THIRD (3):Press the clutch pedal and upshift into
THIRD (3). Then, slowly let up on the clutch pedal as
you press the accelerator pedal.
FOURTH (4), FIFTH (5) and SIXTH (6):Upshift into
the higher forward gears the same way as you do
THIRD (3). Slowly let up on the clutch pedal as you
press the accelerator pedal.
NEUTRAL:Use this position when you start or idle
your engine.
REVERSE (R):To back up, press the clutch pedal.
Wait for the vehicle to stop moving and then, shift
to REVERSE (R). Let up on the clutch slowly while
pressing the accelerator pedal. Also, use REVERSE (R),
along with the parking brake, when turning off your
engine and parking your vehicle.
2-33
Eaton®Fuller®Nine and Ten-Speed
Non-Synchronized Manual
Transmissions
If your vehicle has one of these transmissions the
engine rpm and road speed must match when upshifting
and downshifting. The label above the windshield will
tell you the operating basics you need to know.
The following are driving tips.
•Always choose an initial starting gear suitable for
the load and terrain.
•Always use double-clutching procedures when
shifting.
•Never move the range shift lever to the LO speed
gear position after HI range preselection, or
anytime the transmission is in the HI range.
•Never move the range knob or lever with the shift
lever in NEUTRAL while the vehicle is moving.
•Never make a range shift while moving in
REVERSE (R).
Clutch Brake (Vehicles with
Non-Synchronized Transmission)
A clutch brake is used to stop transmission input shaft
rotation so that FIRST (1) or REVERSE (R) gear
selection can be initiated when the vehicle is at a
standstill and the engine is idling.
Press the clutch pedal all the way down to the floorboard
to apply the clutch brake.
When using the clutch brake, disengage the clutch
pedal and shift the transmission into either the initial
starting gear or REVERSE (R). If the tooth-butting
occurs between the clutching teeth, re-engage the clutch
while applying light pressure to the shift lever. This
will provide for a smooth shift into either FIRST (1) or
REVERSE (R) gear.
Notice:Using the clutch brake for shifting into any
gear other than FIRST (1) or REVERSE (R) may
cause premature wear of the clutch brake and make
gear shift effort more difficult. Do not use the
clutch brake for shifting after engaging FIRST (1) or
REVERSE (R).
2-34
Recommended Transfer Case Settings
Driving ConditionsTransfer Case Settings
2m4m4nN
Normal YES
Severe YES
Extreme YES
Vehicle in Tow* YES
*SeeTowing Your Vehicle on page 4-37for further
information.
2
m(Two-Wheel High):This setting is for driving in
most street and highway situations. The transfer
case does not drive the front axle in two-wheel drive.
The front-axle will spin if the front wheel hubs are
locked. Be sure to unlock the hubs to achieve the best
fuel economy.
4
m(Four-Wheel High):Use Four-Wheel High when
you need extra traction, such as on snowy or icy
roads or in most off-road situations. Be sure the front
wheel hubs are locked when you want to drive in
Four-Wheel High.4
n(Four-Wheel Low):This setting sends maximum
power to all four wheels. You might choose Four-Wheel
Low if you are driving off-road in deep sand, deep
mud, and climbing or descending steep hills. Be sure
the front wheel hubs are locked when you want to drive
in Four-Wheel Low.
{CAUTION:
Shifting the transfer case to NEUTRAL can
cause your vehicle to roll even if the
transmission is in PARK (P). You or someone
else could be injured. If you are going to leave
your vehicle, set the parking brake and shift
the transmission to PARK (P) and make sure
the transfer case is in a drive gear.
Notice:If your vehicle has an Allison
®transmission
and you try to put the transmission in PARK (P)
while the transfer case is in Four-Wheel Low,
the transmission may not go into PARK (P) and
could damage your vehicle. When parking your
vehicle, make sure the transfer case is in Two-Wheel
High or Four-Wheel High.
NEUTRAL:Shift the vehicle’s transfer case to
NEUTRAL only when towing your vehicle.
2-37