Hydraulic brake booster system (Hydromax)
The Hydromax systems receive fluid pressure from the power steering
pump to provide power assist during braking.
The Hydromax booster receives backup pressure from the reserve
system electric pump whenever the fluid in the power steering system is
not flowing. When the engine is OFF, the pump will turn on if the brake
pedal is applied, or if the ignition is turned to the ON position.
The sound of the pump operating may be heard by the driver, but this is
a normal characteristic of the system.
The reserve system provides reduced braking power, so the vehicle
should be operated under these conditions with caution, and only to seek
service repair and remove the vehicle from the roadway.
For Hydromax under normal operating conditions noise of the fluid
flowing through the booster may be heard whenever the brake is applied.
This condition is normal. Vehicle service is not required.
If braking performance or pedal response becomes very poor, even when
the pedal is strongly applied, this may indicate the presence of air in the
hydraulic system or fluid leakage. Stop the vehicle safely as soon as
possible and seek service immediately.
If the red BRAKE warning lamp in
the instrument cluster remains
illuminated after engine start up,
this indicates a system failure in the
master cylinder of the brake system.
Stop the vehicle safely as soon as possible and seek service immediately.
If the yellow BRAKE RESERVE
(E-motor) warning light remains on
while the engine is running, this
indicates inadequate hydraulic
booster pressure or reserve pump
system failure. Stop the vehicle safely as soon as possible and seek
service immediately.
!
BRAKE
BRAKE
Driving
109
Occasional or intermittent brake squeal may result from environmental
conditions such as cold, hot, wet, snow, salt, mud, etc. This condition will
not affect braking effectiveness. The brakes should be checked only if
squeal occurs continuously with every application.
If brakes do not grip well
²If you have been driving through deep water, gently apply the brakes
several times while the vehicle is moving slowly.
²Let the brakes cool if you have been using them excessively, as in
mountain driving or after several fast, high speed stops.
²Check brake adjustment.
²Check brake linings for excessive wear.
²Check system air pressure.
Air brakes
After starting the engine, give the air compressor time to build up the air
pressure to 414 kPa (60 psi) before moving the vehicle.
Do not drive or continue to drive if the low air pressure buzzer
is sounding or the brake warning light is lit. These warnings
indicate that air pressure is not to normal operating level. Continued
use of the vehicle could result in loss of braking ability.
Avoid repeated light application of the brake pedal. This will
deplete air pressure faster and could result in loss of braking
capability.
Periodically check the air pressure
gauge while driving. Pressure should
range between approximately 703 to
930 kPa (105-135 psi). The air
compressor governor cut-in and
cut-out pressure settings are preset
at the factory and are not
adjustable.
0 30 12090 60
150AIR
PRESSUREPSI
Driving
114
R (Reverse)
Use this position to back the vehicle. Completely stop the vehicle before
shifting from R (Reverse) to any forward gear (1, 2, 3 or D). The reverse
warning signal will sound when the selector is in R (Reverse). Reverse
has only one gear and provides the greatest gear reduction.
N (Neutral)
Place the selector in N (Neutral) before starting the engine. Shift to N
(Neutral) and set the parking brake any time the engine is to be running
while the operator is not at the controls. The engine should be at idle
speed when any shift from N (Neutral) to a drive range is made.
D (Drive-Normal driving position)
The transmission starts in first gear and automatically shifts through
second, third and fourth depending on load and speed demands. This
range is used for highway driving under normal conditions.
3 and 2 (Third and Second)
Use these ranges when road, load or traffic conditions require a lower
gear. These ranges provide greater engine braking than D (Drive). When
conditions are improved that no longer require these lower gears, shift
back to D (Drive).
1 (First)
The transmission has to be manually shifted into 1 (First) and will not
shift into a higher gear. This range is used for extra heavy loads or where
maximum reduction is required.
Allison MD Series transmissions
These transmissions have no P (Park) position. Before leaving
the driver's seat, always shift into N (Neutral) and set the
parking brake. Shut off the engine and remove your ignition key.
Always use wheel chocks for hilly or off-road parking. Unexpected and
possibly sudden vehicle movement may occur if these precautions are
not taken.
These transmissions are electronically controlled and have a push button
shifter. MD transmissions are available in five- or six-speed driving
ranges.
Driving
132
These transmissions have no P (Park) position. Before leaving
the driver's seat, always shift into N (Neutral) and set the
parking brake. Shut the engine off and remove your ignition key.
Always use wheel chocks for hilly or off-road parking. Unexpected and
possibly sudden vehicle movement may occur if these precautions are
not taken.
Gearshift positions
R (Reverse)- Use this position to
back the vehicle. Completely stop
the vehicle before shifting from R
(Reverse) to any forward gear. The
reverse warning signal will sound
when the selector is in R (Reverse).
Reverse has only one gear and
provides the greatest traction. The
Select and Monitor indicators will
display R when reverse is attained.
N (Neutral)- Use N (Neutral) for
starting the engine. If the engine
starts in any gear other than N
(Neutral), the start circuit should be
serviced immediately. Shift to N
(Neutral) and set the parking brake
any time the engine is to be running
while the operator is not at the
controls. The engine should be at
idle speed when any shift from N
(Neutral) to a drive range is made.
The Select and Monitor indicators
will display N.
Do not allow your vehicle to coast in N (Neutral). Transmission
braking is not available in N (Neutral). This practice can also
result in transmission damage.
D N R
MODE
D N R
MODE
Driving
134
Allison 2000 series
These transmissions have no P (Park) position. Before leaving
the driver's seat, always shift into N (Neutral) and set the
parking brake. Shut off the engine and remove your ignition key.
Always use wheel chocks for hilly or off-road parking. Unexpected and
possibly sudden vehicle movement may occur if these precautions are
not taken.
This transmission provides five forward speeds in four ranges and one
reverse range.
R (Reverse)
Use this position to back the vehicle. Completely stop the vehicle before
shifting from R (Reverse) to any forward gear (1, 2, 4 or D). The reverse
warning signal will sound when the selector is in R (Reverse). Reverse
has only one gear and provides the greatest gear reduction.
N (Neutral)
Place the selector in N (Neutral) before starting the engine. Shift to N
(Neutral) and set the parking brake any time the engine is to be running
while the operator is not at the controls. The engine should be at idle
speed when any shift from N (Neutral) to a drive range is made.
Do not allow your vehicle to coast in N (Neutral). Engine
braking is not available in N (Neutral). Allowing your vehicle to
coast in N (Neutral) may result in loss of vehicle control and severe
internal transmission damage.
D (Drive-Normal driving position)
In this position, the transmission starts in first gear and automatically
shifts through second, third, fourth and fifth depending on load and
speed demands. When the vehicle is slowing down, the transmission will
automatically downshift. This range is used for highway driving under
normal conditions.
4 and 2 (Fourth and Second)
Use these ranges when road, load or traffic conditions require a lower
gear. These ranges provide greater engine braking than D (Drive). When
conditions are improved that no longer require these lower gears, shift
back to D (Drive).
Driving
136
1 (First)
The transmission has to be manually shifted into 1 (First) and will not
shift into a higher gear. Use this position when pulling through mud or
snow, driving up steep grades, hauling extra heavy loads or where
maximum reduction is required.
Allison 2400 series
This transmission provides five forward speeds in four ranges and one
reverse range.
P (Park)
Use this position when you start the engine. The engine is designed to
start in the P (Park) or N (Neutral) position only.
Always come to a complete stop before shifting into P (Park). Make sure
the gearshift is securely latched in P (Park). This position locks the
transmission and prevents the rear wheels from turning.
Always set the parking brake fully and make sure the gearshift
lever is latched in P (Park). Turn off the ignition whenever you
leave your vehicle.
When parking on hilly or off-road terrains, be sure to set the parking
brake fully and chock the wheels to prevent unexpected and possibly
sudden vehicle movement.
R (Reverse)
Use this position to move the vehicle backwards. Completely stop the
vehicle before shifting from a forward gear (1, 2, 4 or D) to R (Reverse),
or from R (Reverse) to any forward gear. The reverse warning signal will
sound when the selector is in R (Reverse). Reverse has only one gear
and provides the greatest gear reduction.
N (Neutral)
This position can be used when starting the engine. The engine is
designed to start in the P (Park) or N (Neutral) position only. The
engine should be at idle speed when any shift from N (Neutral) to a
drive range is made.
The N (Neutral) position may also be used during stationary operation of
the Power Take-Off (PTO), if equipped.
Driving
137
Do not allow your vehicle to coast in N (Neutral). Engine
braking is not available in N (Neutral). Allowing your vehicle to
coast in N (Neutral) may result in loss of vehicle control and severe
internal transmission damage.
D (DriveÐNormal driving position)
In this position, the transmission starts in first gear and automatically
shifts through second, third, fourth and fifth depending on load and
speed demands. When the vehicle is slowing down, the transmission will
automatically downshift. This range is used for highway driving under
normal conditions.
4 and 2 (Fourth and Second)
Use this position when road, load or traffic conditions make it desirable
to restrict the automatic shifting to a lower range. These ranges provide
greater engine braking than D (Drive). When conditions no longer
require these lower gears, shift back to D (Drive).
1 (First)
The transmission has to be manually shifted into 1 (First) and will not
shift into a higher gear. Use this position when pulling through mud or
snow, driving up steep grades, hauling extra heavy loads or where
maximum reduction is required.
Power take-off (PTO) operation with an Allison automatic
transmission (except MD applications and vehicles equipped with
a Caterpillar 3126E engine)
The power take-off can be operated while the vehicle is standing or
moving.
To engage the PTO, apply the brakes and shift to any gear other than N
(Neutral) - this stops the rotation of the PTO drive gear in the
transmission - 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
selector to N (Neutral) and then back in 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. This could result in further
damage to the transmission and PTO.
Driving
138
Fuse/Relay
LocationFuse Amp
RatingPassenger Compartment Fuse
Panel Description
6 Ð Not Used
7 Ð Not Used
8 5A Radio, GEM
9 5A Switch Illumination (Headlamp,
Power Windows, Power Door
Locks), Power Window Relay,
Trailer Hook Up Lamps
(SuperCrewzer only)
10 Ð Not Used
11 30A Wiper Motor, Washer Pump Relay
12 10A Stoplamp Switch (Hydraulic
Vehicles Only)
13 20A Radio, Cluster, 7.3L Power Stroke
Powertrain Control Module
(PCM), Keep Alive Memory
14 10A Interior Lamps, Runningboard
lamps (SuperCrewzer only)
15 10A GEM, Interior Lamp Relay, Map
Lamps, Glove Box Lamps
(SuperCrewzer only), Power
Mirrors (SuperCrewzer only),
Warning Chime Module
(SuperCrewzer only)
16 15A Highbeams
17 Ð Not Used
18 5A Headlamp switch, GEM
19 15A Engine, Cluster, Cummins PC M,
CAT PCM, 7.3L Power Stroke
PCM (Idle Valid Switch Input)
20 15A Starter Relay, GEM
21 10A Daytime Running Lamps (DRL)
22 15A Exhaust Brake (SuperCrewzer
only), Heated Mirrors
(SuperCrewzer only), Rear Air
Suspension (SuperCrewzer only)
Roadside emergencies
146