warning FORD F750 2012 12.G Repair Manual

may be limited and your vehicle may stall. Water may also enter your
engine’s air intake and severely damage your engine, drive axles or the
transmission (through the breather ports).
Once through the water, always dry the brakes by moving your vehicle
slowly while applying light pressure on the brake pedal. Wet brakes do
not stop the vehicle as quickly as dry brakes.
ENGINE AUTOMATIC SHUTDOWN WARNING LIGHT OR CHIME
(IF EQUIPPED)
This feature illuminates a light in the instrument cluster and/or sounds a
chime indicating that the engine is being shut down in the event of high
coolant temperature, low engine oil pressure, high diesel particulate filter
soot loading or low engine coolant level. In the event any of these
conditions exist, the engine automatically shuts down.
If the engine shuts down, it can be restarted and operated for
30 seconds at a time or until the problem is corrected. Do not attempt to
use this restarting feature to drive the vehicle very far as serious engine
damage could result.
WARNING:In the event of engine shutdown, make sure the
vehicle is safely off the road and the problem is remedied prior
to returning to the road. Failure to remove the vehicle from the road
could result in an accident, causing serious injury or death.
GENERAL BRAKE INFORMATION
All standard equipment brakes are designed to be self-adjusting.
Automatic adjustment, when required, occurs whenever the brakes are
applied and released during forward or reverse operation. Refer to the
Scheduled Maintenance Guidechapter for scheduled maintenance.
Occasional brake noise is normal and often does not indicate a performance
concern with the vehicle’s brake system. In normal operation, automotive
brake systems may emit occasional or intermittent squeal or groan noises
when the brakes are applied. Such noises are usually heard during the first
few brake applications in the morning; however, they may be heard at any
time while braking and can be aggravated by environmental conditions
such as cold, heat, moisture, road dust, salt or mud. If a “metal-to-metal,”
“continuous grinding” or “continuous squeal” sound is present while
braking, the brake linings may be worn-out and should be inspected by a
qualified service technician.
Know the required stopping distances for all driving conditions that may
be encountered. For longer brake lining life, take full advantage of engine
braking power when coming to a stop.
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WARNING:Do not drive with your foot resting on the brake
pedal. This results in abnormally high brake temperatures,
excessive lining wear and increased stopping distances.
Before descending a long or steep hill, shift to a lower gear and avoid
continuous application of the brakes. Normally, choose the same gear to
descend the hill that you use to ascend the hill.
WARNING:Continuous application of the brakes causes the
brakes to overheat, resulting in a temporary loss of braking.
If brakes do not grip well
•If you have been driving through deep water, gently apply the brakes
several times while the vehicle is moving slowly.
•Let the brakes cool if you have been using them excessively, as in
mountain driving or after several fast, high-speed stops.
•Check brake adjustment.
•Check brake linings for excessive wear.
•Check system air pressure on vehicles equipped with air brakes.
HYDRAULIC BRAKES (IF EQUIPPED)
Full Power Brake System
This system incorporates standard braking, an anti-lock braking system
(ABS) and optional Power Park Brake into one fully-integrated hydraulic
brake system. With the Full Power Brake System, braking energy is
stored, similar to an air brake system, resulting in faster response times
and shorter stopping distances. This is accomplished using motor/pump
assemblies that pressurized the system by pumping brake fluid into
accumulators. This is similar to the air compressor of an air brake system
pressurizing the air tanks. The system includes a master cylinder that
provides the normal pedal “feel” and transfers the pedal force, via brake
fluid, to the main components of the system.
Note:The motor/pumps run momentarily with the ignition switch in the
on or run positions or the switch is in the off position and the brake
pedal is pressed.
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WARNING:If the red BRAKE warning lamp in the instrument
cluster remains illuminated after engine start up, this indicates a
system failure in the Full Power Brake System. Stop the vehicle safely
as soon as possible and seek service immediately.
Note:During normal driving the pump/motors may be heard
replenishing the accumulators; this is a normal function of the system.
Parking brake
Apply the parking brake whenever
the vehicle is parked. To set the
parking brake, pull handle up until it
snaps into the locked position.
WARNING:Do not use the
gearshift selector in place of
the parking brake. Always set the
parking brake fully AND make
sure the gearshift selector is in R
(Reverse) for vehicles equipped
with manual transmission, P
(Park)(if equipped)or N
(Neutral) for vehicles with
automatic transmission. Use of
wheel chocks is also
recommended in hilly or off-road
usage.
WARNING:Unexpected and possible sudden vehicle movement
may occur if these precautions are not taken.
When the parking brake is out of adjustment, seek service immediately.
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The parking brake warning lamp in
the instrument cluster illuminates,
and remains illuminated (when the
ignition is turned on), until the
parking brake is released.
Push the palm release lever on the
parking brake handle and push
down as far as possible to release
the brake. Driving with the parking
brake on causes the brakes to wear
out quickly and reduce fuel
economy.
WARNING:If the parking brake is fully released but the parking
brake warning lamp remains illuminated, the brakes may not be
working properly. See your dealer or a qualified service technician.
The parking brake is not recommended to stop a moving vehicle.
However, if the normal brakes fail, the parking brake can be used to stop
your vehicle in an emergency. Since the parking brake only applies
retardation to the rear wheels, the vehicle’s stopping distance increases
greatly and the handling of your vehicle is adversely affected.
P
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POWER PARK (PARKING BRAKE) OPTION (IF EQUIPPED)
This feature uses a brake chamber mounted on the chassis to power a
spring-applied, hydraulically-released driveline parking brake. It is
controlled by a yellow, dash-mounted parking brake knob.
The Power Park Brake is controlled by the park brake dash-mounted,
yellow knob-type switch. The switch has three positions: apply (out),
neutral (central), and release (in). The switch is spring-loaded to return
to the neutral (central) position after being pushed or pulled.
There is no visual indication at the knob that the park brake is applied or
released; check the instrument cluster. If the
light is illuminated,
the parking brake is applied.
Applying the parking brake
To apply the parking brake, pull the yellow, dash-mounted parking brake
knob. A red light (
) in the instrument cluster should illuminate
indicating that the parking brake has been successfully set.
Note:If the
light blinks and a warning chime sounds when the
control knob is pulled, the parking brake is not functioning properly;
seek immediate service from your dealer. Refer toParking brake
warning systemin this section.
Releasing the parking brake
Note:Read and understand the following steps and perform them
whenever you prepare to drive the vehicle.
Note:The parking brake does not disengage unless sufficient system air
pressure is available.
Automatic transmissions - dash-mounted push button (Allison
3000 Series) and steering column-mounted (Allison 2200 and 2500)
gear selection:
1. With the engine running, press and hold the service brake pedal.
2. Select the appropriate drive gear.
3. Push and hold the yellow, dash-mounted parking brake knob until
the
light turns off, then release.
Manual transmissions - (TTC 7–speed, Eaton/Fuller 5–speed and
6–speed):
1. With the engine running, press and hold the service brake pedal.
2. Press and hold the clutch pedal.
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3. Select the appropriate drive gear.
4. Push and hold the yellow, dash-mounted parking brake knob until
the
light turns off, then release.
WARNING:Hold the brake pedal down while moving the
gearshift lever from position to position. If the brake pedal is not
held down, the vehicle may move unexpectedly resulting in property
damage, personal injury or death.
Parking brake light illumination due to low air pressure
If at any time during vehicle operation air pressure becomes too low, the
parking brake may apply and the
light turns on.
If the parking brake is applied due to low air pressure, immediate service
is required to the parking brake system.
Parking brake warning system (hydraulic brake vehicles only)
If the
light blinks and a chime sounds when pulling the yellow
control knob out, this indicates the parking brake is not functioning
properly; seek service for the parking brake immediately.
With the ignition key not in the run position:
•A chime sounds if the parking brake remains released (or in an
unknown state). The chime extinguishes in approximately eight
minutes or until the parking brake is applied. Seek service for the
parking brake immediately.
Parking brake light (
) operation (light only works when the ignition
key is in the run position):
•On - Parking brake applied
•Off - Parking brake released and no faults/malfunctions
•Blink and chime - Parking brake released (or unknown) and
faults/malfunctions exist
Releasing spring manually
WARNING:Do not attempt to disassemble the parking brake
chamber under any circumstances. The high spring load may
cause serious injury.
If hydraulic pressure is released from the spring brake chamber the
power spring applies the brake and, unless hydraulic pressure can be
re-established, the spring brake must be released as follows in order to
move the vehicle.
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WARNING:Block the wheels to help prevent the vehicle from
moving.
WARNING:Unexpected and possibly sudden vehicle movement
may occur if these precautions are not taken.
Loosen the jam nut (1) and un-thread the adjustment rod (2) from the
chamber to reduce tension on the cable (3). Continue to un-thread the
adjustment rod all the way and remove it from the chamber. The nut and
shaft are metric.
AIR BRAKES (IF EQUIPPED)
General air brake information
After starting the engine, give the air compressor time to build up the air
pressure to 60 psi (414 kPa) before moving the vehicle.
WARNING: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.
WARNING:Avoid repeated light application of the brake pedal.
This depletes air pressure faster and could result in loss of
braking capability.
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Periodically check the air pressure
gauge while driving. Pressure should
range between approximately
100–125 psi (690–862 kPa). The air
compressor governor cut-in and
cut-out pressure settings are set at
the factory and are not adjustable.
When air pressure is insufficient
(below 60 psi [414 kPa]), a warning
light illuminates and a buzzer
sounds when the ignition is in the
on position.
This condition may be caused by excessive brake applications depleting
the system air pressure. If this condition occurs, stop driving the vehicle
until the compressor has fully recharged the air system.
WARNING:Do not move the vehicle when the air pressure is
insufficient because the brake system may be inoperative.
Select a gear ratio to help slow your vehicle before descending grades.
Supplement with brakes as required to safely slow the vehicle and avoid
overspeeding the engine.
Air chamber stroke indication
Air chamber push rods have orange stroke indicator markers that warn
when the braking system requires adjustment or repair. The orange
stripe is painted on the air chamber push rod at the slack adjuster stroke
dimension which requires service when visible during brake application.
Air brake inspection and adjustment or repairs should be performed by a
qualified service technician in accordance with the instructions in the
service manual.
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Cam brakes - automatic slack adjusters
Standard air brakes (cam) are
equipped with automatic brake
adjusters. Automatic adjustment
occurs during brake applications.
Inspect brakes for proper
adjustment at the intervals listed in
theScheduled Maintenance Guide
chapter.
WARNING:Do not manually adjust the automatic slack
adjusters to correct excessive push rod stroke as it may result in
reduced brake effectiveness and a vehicle crash. Excessive push rod
stroke indicates that a problem exists with the automatic adjuster, with
the installation of the adjuster, or with foundation brake components
that manual adjustment does not remedy. Seek service from a qualified
facility for excessive push rod stroke.
Emergency air brake
All vehicles are equipped with a dual brake system. In the unlikely event
of a failure of one system, the second system functions for emergency
stopping. These systems are all controlled by the brake pedal in the
same manner as for normal stops.
WARNING:Do not continue to operate the vehicle with a
failure of one of the brake systems. Take the vehicle to your
dealer for service immediately.
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Air brake reservoir draining
WARNING:Failure to drain air brake reservoirs can result in a
reduction or loss of braking ability due to fluid accumulation in
the reservoir and/or possible freeze-up during cold weather.
Drain all the air brake reservoirs
daily, completely to 0 psi/kPa, by
opening the draincock at the ends
of the tanks (where accessible.
Pull-chains are used when the
drains are undercab or otherwise
inaccessible). Close draincock after
complete draining. Air tanks
equipped with automatic moisture
ejector valves may also be drained
manually as required to maintain a
dry air system. Contact your dealer if you are unsure of the air reservoir
locations or the draining procedure.
Parking brake
WARNING:Do not use the gearshift selector in place of the
parking brake; unexpected and possible sudden vehicle
movement may occur if these precautions are not taken. Always set
the parking brake fully AND make sure the gearshift selector is in R
(Reverse) for vehicles equipped with manual transmission, N (Neutral)
for vehicles with automatic transmission (except Allison 2200
transmission) or P (Park) (Allison 2200 transmission).
If the service brakes should fail to operate while the vehicle is in motion,
you can make an emergency stop with the parking brake. Since the
parking brake only applies stopping power to the rear wheels, the
vehicle’s stopping distance greatly increases and the handling of the
vehicle is adversely affected. Repairs should be made immediately to an
inoperative air brake system circuit.
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