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AUTOMATIC TRANSMISSION OPERATION (IF EQUIPPED)
WARNING:Hold the brake pedal down while you move the
gearshift lever between positions. If you do not hold the brake
pedal down, your vehicle may move unexpectedly and cause property
damage, personal injury or death.
Main transmission, auxiliary transmission, transfer case and power
take-off (PTO) control shift patterns can be found on a placard or decal
on the driver’s sun visor, on the instrument panel or on the shift control
itself.
The main transmission control is used to select the various gear ratios or
speeds of the transmission. Selecting positionDdoes not change the
transmission gear ratio, but is used where the gear ratios in the main
transmission are adequate to handle the vehicle operation.
If the transmission fails to shift properly, check the inline 10A fuse
located in the battery cables above the battery.
Brake-shift Interlock
Vehicles equipped with a gasoline engine have a brake-shift interlock
feature that prevents the gearshift lever from being moved from position
Pwhen the ignition is in the on position and the brake pedal is not
pressed.
If you cannot move the gearshift lever out of positionPwith the ignition
in the on position and the brake pedal pressed, it is possible that a fuse
has blown or the vehicle’s brake lamps are not operating properly. See
theFuseschapter.
WARNING:Do not drive your vehicle until you verify that the
brake lamps are working.
WARNING:When doing this procedure, you will be taking the
vehicle out of park which means the vehicle can roll freely. To
avoid unwanted vehicle movement, always fully set the parking brake
prior to doing this procedure. Use wheel chocks if appropriate.
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WARNING:If the parking brake is fully released, but the brake
warning lamp remains illuminated, the brakes may not be
working properly. See your authorized dealer.
If the fuse is not blown and the brake lamps are working properly, the
following procedure allows you to move the gearshift lever from positionP:
1. Apply the parking brake, and
turn the engine off.
2. Remove the lower finish panel
below the steering column.
3. Turn the key to the on position,
but do not start the engine.
4. Pull back on the solenoid, and
at the same time, shift the
transmission into positionN.
5. Start the vehicle.
See your authorized dealer as
soon as possible if this
procedure is used.
Six–speed TorqShift® Transmission
WARNING:Always set the parking brake fully and make sure
the gearshift is latched in position P. Turn the ignition to the off
position and remove the key whenever you leave your vehicle.
WARNING:Do not use the tow/haul feature when driving in icy
or slippery conditions as the increased engine braking can cause
the rear wheels to slide and the vehicle to swing around with the
possible loss of vehicle control.
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Position P
This position locks the transmission and prevents the rear wheels from
turning.
To put your vehicle in gear:
1. Start the engine.
2. Press the brake pedal.
3. Move the gearshift lever into the desired gear.
To put your vehicle in positionP:
1. Come to a complete stop.
2. Move the gearshift lever and securely latch it in positionP.
Position R
With the gearshift lever in positionR,the vehicle moves backward. Always
come to a complete stop before shifting into and out of positionR.
Position N
With the gearshift lever in positionN,the vehicle can be started and is
free to roll. Hold the brake pedal down while in this position.
Position D
This is the normal driving position for the best fuel economy. This
position allows automatic upshifts and downshifts in gears one through
six.
Position 4
This position allows automatic upshifts and downshifts in gears one
through four.
Position 2
Use position2to start-up on slippery roads or to provide additional
engine braking on downgrades.
PRND 4 2 1
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Position 1
•Provides maximum engine braking.
•Allows upshifts by moving gearshift lever.
•The transmission does not downshift into position1at high speeds; it
downshifts to a lower gear and then shifts into position1when the
vehicle reaches slower speeds.
Forced Downshifts
•Allowed in positionD.
•Press the accelerator to the floor.
•Allows transmission to select an appropriate gear.
Allison 2200 with Parking Pawl Feature
Note:Also see the separateAllison Transmission Operator’s Manual.
WARNING:Always set the parking brake fully. Do not use the
gearshift in place of the parking brake.
WARNING: To avoid sudden, unexpected vehicle movement
and possible personal injury or death:
1. Bring the vehicle to a complete stop.
2. Shift the transmission into positionP.Slowly lift your foot from the
brake pedal to engage the transmission parking pawl mechanism.
3. Apply the parking brake and make sure it is holding properly. Do not
rely solely on the parking mechanism of the transmission.
4. Turn the engine off when you leave the vehicle.Never leave the
vehicle unattended when the engine is running.
A parking pawl effectively grounds the transmission’s output shaft
preventing rotation of the driveline. If the vehicle is stationary, selecting
positionPplaces the transmission in neutral and engages the parking
pawl. Always use the parking brake when parking the vehicle.
Note:If positionPis selected when the vehicle is in motion, the parking
pawl mechanism ratchets andDOES NOThold the truck.
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Allison 2500
WARNING: To avoid sudden, unexpected vehicle movement
and possible personal injury or death:
1. Bring the vehicle to a complete stop.
2. Shift the transmission into positionN.
3. Apply the parking brake and make sure it is holding properly.
4. Turn the engine off when you leave the vehicle.Never leave the
vehicle unattended when the engine is running.
This transmission is available with a column-mounted gearshift lever. The
gear positions are displayed on the RNDL in the instrument cluster.
Allison 3000
Note:For more information regarding this transmission, see the separate
Allison 3000 Series Operator’s Manual.
The Allison 3000 series offers two shift modes: Performance and
Economy.
Performance mode gives the best all-around transmission operation. The
transmission defaults to this mode when you start the engine. Pressing
MODE on the shifter switches to Economy mode and illuminates the
Mode ON lamp.
Economy mode provides operation at lower engine RPM while
maintaining adequate performance.
If the engine speed is above idle when a gear is selected using the
shifter, the vehicle does not move; the shifter must be moved to re-select
a gear after the engine speed returns to idle.
Torque Lock
If your vehicle is parked on an incline and positionPis not properly
engaged (the parking brake is not applied before the transmission is
shifted into positionP),the weight of the vehicle may generate an
excessive amount of torque on the parking pawl, making it difficult to
shift the transmission out of positionP.Hold the brake pedal down while
shifting out of positionP,then release the parking brake.
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Allison 3000 Series Push-Button Shifter
To shift to Reverse or Drive:
1. Press the brake pedal.
2. Press R or D on the shifter.
3. Release the brake pedal.
To select a higher range when in
Drive, press the up arrow button.
To select a lower range when in
Drive, press the down arrow button.
To place the transmission in Neutral,
press N.
Allison 3000 Prognostics
This transmission is equipped with the Allison Prognostics feature that
can alert the driver to needed transmission maintenance and
transmission fluid and filter life. See the separate Allison transmission
manual for complete details.
POWER TAKE-OFF (PTO) OPERATION (IF EQUIPPED)
A PTO unit allows the transmission to power auxiliary equipment to run
devices such as snowplows, aerial lifts, tow truck lifts, cement mixers or
dump trucks.
Vehicles Equipped with an Allison Automatic Transmission
(Except 3000 Series)
The PTO can be operated while the vehicle is standing or moving.
To engage the PTO, apply the brakes and shift to any gear other than
positionN,then engage the PTO.
If engagement is prevented by the gear teeth not meshing properly,
release the brakes and allow the vehicle to creep slightly or shift the
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selector to positionNand then back into gear. The PTO should never be
engaged by clashing the gear teeth. This may damage the PTO unit and
the transmission PTO drive gear teeth, resulting in further damage to the
transmission and PTO.
PTO Operation with Vehicle Stationary
WARNING:When the PTO is operated with the vehicle
stationary, the transmission must be placed in positionNwith the
parking brake set. If the transmission is not in positionNand is
equipped with a remote throttle control, an increase in engine speed
can overpower the parking brake and cause the vehicle to move,
possibly resulting in personal injury and/or property damage.
Stop the vehicle, idle the engine and set the parking brake. Make sure
the gear selector is in any forward drive range, then engage the PTO.
After the PTO is engaged, move the range selector to positionN.
Increase the engine speed until the desired PTO operation speed is
obtained. To disengage the PTO after operation with the vehicle
standing, release the throttle, allow the drive equipment to come to a
stop, and then disengage the PTO.
PTO Operation while Vehicle Is Moving
After the PTO is engaged for driven vehicle operation, shift to the
desired range and drive the vehicle. The speed of the PTO, during this
period of operation, always maintains direct relation to vehicle speed.
PTO speed decreases in relation to vehicle (transmission output) speed
as shifts to a higher gear occur. When operating the PTO while the
vehicle is moving, the PTO may be disengaged whenever it is no longer
required. When there is no load on the PTO gear, it can be pulled out of
engagement.
Vehicles Equipped with an Allison 3000 Series Automatic
Transmission
The PTO drive gear is engine-driven and provides direct engine power.
The PTO can be operated when the vehicle is either stationary or
moving. The PTO gear is in constant mesh with the drive gear in the
torque converter housing. A friction clutch or constant drive is used to
transmit power to the PTO.
Vehicles Equipped with a Manual Transmission
Transmission-mounted PTO units are available for local installation on
your vehicle. See yourBody Builder’s Layout Bookfor restrictions on
use and installation of PTO units.
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To engage the PTO unit, stop the vehicle and place the transmission in
positionN.Press the clutch and allow the gears to stop rotating, then
engage the PTO unit. The PTO can also be selected with the
transmission in gear as long as the clutch is pressed.
When operating the PTO with the vehicle stationary, first set the parking
brake (chock the wheels if the vehicle is on a hill or another uneven
surface).
REAR AXLES
Gross Axle Weight
WARNING:Exceeding these ratings by overloading can cause
component failure resulting in property damage, personal injury
or death.
Your truck has gross axle weight, gross vehicle weight and gross
combination weight ratings. Do not exceed these ratings.
Locking or Limited-Slip Differentials
WARNING:If both wheels are not raised off the ground, the one
wheel that is not raised may pull the vehicle off its support,
possibly resulting in personal injury
If your vehicle is equipped with a locking or limited-slip differential, note
the following:
•Power is transmitted to the opposite wheel should one of the wheels
begin to slip.
•Both wheels must be raised off the ground should it be necessary to
operate one wheel with the vehicle stationary.
Driver-controlled Differential Lock
Note:Never use the differential lock at vehicle speeds above 25 mph
(40 km/h).
Some drive axles have a driver-controlled differential lock. The
differential lock can lock or unlock the differential when the vehicle is
moving or stopped. When extra traction is required, the differential lock
provides full power to both axles.
When the differential is locked, the vehicle’s turning radius increases
(under-steer).
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