2008 FORD F750 differential

Brake system warning light:To
confirm the brake system warning
light is functional, this light will
momentarily illuminate when the
ignition is turned to the ON position when the engine is not running. If
the brake system warning light does not illuminate at this time, seek
service immediately from your dealership. Illumination after starting the
vehicle indicates a pressure differential in the master cylinder and the
brake system should be inspected immediately by your dealership.
If equipped with an air brake system, the warning light stays on until the
air pressure builds up to 60 psi (414 kPa). If the air pressure drops
below 60 psi (414 kPa) during operation, the remaining brake system is
still operational but the stopping distance will be greater.
Driving a vehicle with the brake system warning light on is
dangerous. A significant decrease in braking performance may
occur. It will take you longer to stop the vehicle. Have the vehicle
checked by your dealer immediately. Driving extended distances with
the parking brake engaged can cause brake failure and the risk of
personal injury.
Wait to start:Indicates the air
intake heater is in operation and
special starting procedures are
required. Refer to theDriving
chapter.
If equipped with an air intake heater, DO NOT use ether or any
other starting fluids. The use of starting fluids (ether) in an
engine equipped with an air intake heater could result in damage
and/or personal injury.
WAIT
TO
START
2008 F-650/750(f67)
Supplement
USA(fus)
Instrument Cluster
23

Water in fuel:During refueling, it
is possible for water-contaminated
diesel fuel to be pumped into your
tank. Your vehicle fuel system is
equipped with a fuel filter/water
separator to remove water from the fuel. The WATER IN FUEL light will
illuminate when the fuel filter/water separator has a significant quantity
of water in it.
If the light illuminates when the engine is running, stop the vehicle as
soon as safely possible, shut off the engine, then drain the fuel
filter/water separator. Refer to your engine operator’s manual for the
drain procedure. Allowing water to stay in the system could result in
extensive damage to, or failure of, the fuel injection system.
Do not drain water separator while engine is running. Fuel may
ignite if separator is drained while engine is running or vehicle is
moving.
Traction control (if equipped):
Illuminates and flashes slowly if the
Off Road mode is selected and
flashes rapidly during a traction
control event.
Differential lock:Illuminates when
the main differential is locked
(engaged).
Parking brake warning:
Momentarily illuminates when the
ignition is turned to the ON position
and the engine is off. Also
illuminates when the parking brake
is engaged. If the brake warning
lamp does not illuminate at these
times, seek service immediately.
Vehicles equipped with the Power Park (air-operated parking
brake) option:If after setting the parking brake on your vehicle the
park brake warning lamp begins to blink, this may indicate a failure in
the parking brake system. Seek service from your dealer immediately.
WATER
IN
FUEL
P
BRAKE
2008 F-650/750(f67)
Supplement
USA(fus)
Instrument Cluster
24

and seals, requiring axle lubrication changes to become more frequent to
preserve the axle. Extreme Pressure (EP) lubricants should not be run
consistently above 230°F (110°C).
Gross axle weight
Your truck has gross axle weight, gross vehicle weight and gross
combination weight ratings. Do not exceed these ratings.
Exceeding these ratings by overloading can cause component
failure resulting in property damage, personal injury or death.
Rear axles with locking or limited-slip differentials (if equipped)
If your vehicle is equipped with a locking or limited-slip differential, note
the following:
•Power will be 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.
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
Driver-controlled differential lock
To prevent the vehicle from moving when servicing the wheels, tires or
brakes, turn the engine off and raise all drive wheels of the locker
differential axle. Axles equipped with NoSPIN Detroit Locker differentials
deliver power to both wheels even when only one wheel is on the
ground.
Failure to raise all drive wheels with this type of differential
could cause the vehicle to move unexpectedly, resulting in
property damage, personal injury or death.
Care should be taken to avoid sudden accelerations when both drive
wheels are on a slippery surface.
Sudden accelerations on slippery surfaces could cause the
wheels to spin, the vehicle to turn sideways on a crowned road
surface or in a turn, possibly resulting in loss of vehicle control and
personal injury.
2008 F-650/750(f67)
Supplement
USA(fus)
Driving
124

Some Dana/Spicer 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 will provide full power to both axles.
When the differential is locked, the vehicle’s turning radius will increase
(vehicle will “under-steer”)
The differential can be locked or unlocked when the vehicle is moving at
a constant speed of less than 25 mph (40 km/h) and while the wheels
are not slipping. The differential must not be locked when the vehicle is
traveling down steep grades and traction is minimal.
Note:Never use the differential lock at vehicle speeds above 25 mph
(40 km/h).
Note:The driver-controlled differential lock function will vary with some
transmissions.
•Vehicles equipped with an Allison 3000 Series transmission:The
differential lock and differential lock light will automatically disengage
at speeds above 25 mph (40 km/h). The differential lock will remain
off until either the vehicle is restarted or the differential lock switch is
turned off then back on.
•Vehicles equipped with a 5–speed, 6–speed or 7–speed manual:
The differential lock and differential lock light will automatically
disengage at speeds above 25 mph (40 km/h). The differential lock
will remain off until either the vehicle is restarted or the differential
lock switch is turned off then back on.
Axle conversions
It is not recommended, or approved, for axle conversions to be
performed. However, it is understood that, on occasion, aftermarket
add-on axles are installed by others on the truck chassis which allow
operator control for weight transfer from other axles (i.e., air lift axles).
When operating a loaded vehicle, the driver must keep all
adjustable axles on the ground at all times, supporting their
share of the vehicle’s load. Failure to do so can overload other axles,
tires, wheels, springs, steering components, brakes and frames,
resulting in early component failure, loss of vehicle control, possible
property damage and personal injury.
TWO-SPEED REAR AXLE (IF EQUIPPED)
A two-speed rear axle allows the driver to select a LO range for greater
pulling power and a HI range for greater road speed and fuel economy.
2008 F-650/750(f67)
Supplement
USA(fus)
Driving
125

Fuse/Relay
LocationFuse Amp
RatingFuse Description
15 10A Interior lamp relay, GEM, Vanity mirrors
16 15A High beams, Indicator
17 — Not used
18 5A Headlamp switch interior lighting
19 15A Engine control
20 5A Starting system
21 10A DRL resistor
22 15A Air horn, Air suspension dump, Two-speed
axle, Driver-controlled locking differential
23 10A Flasher
24 15A ABS, Air dryer, Vacuum pump, Fuel heater
relay
25 10A Function selector switch
26 10A RH low beam headlamp
27 — Not used
28 10A LH low beam headlamp
29 10A Cluster warning lamps, Gauges, GEM,
Hydraulic ABS
30 15A Allison electronic transmission
31 — Not used
Relay 1 — Interior lamps
Relay 2 — Not used
Relay 3 — Horn
Relay 4 — One-touch down window
Relay 5 — Not used
Power distribution box
Always disconnect the battery before servicing high current
fuses.
2008 F-650/750(f67)
Supplement
USA(fus)
Roadside Emergencies
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4. Remove the jumper cable from the positive (+) terminal of the
disabled vehicle’s battery.
After the disabled vehicle has been started and the jumper cables
removed, allow it to idle for several minutes so the engine computer can
relearnits idle conditions.
WRECKER TOWING INSTRUCTIONS
Before moving the towed vehicle, check for adequate road clearance of
vehicle components. It is recommended the towed vehicle be unloaded
prior to being towed to reduce any abnormal load to the vehicle
components resulting from the towing procedures. Before towing, be
sure to fully release the parking brake. The spring-actuated type parking
brake can be reset by recharging the air system with at least 64 psi
(441 kPa) of air. If the brake system will not retain air pressure, then the
spring brakes must be released manually. Refer toParking brakein the
Drivingchapter
Note:For towing, make sure the vehicle is securely connected to the
tow vehicle and the tow vehicle parking brakes are applied before
releasing the disabled vehicle’s spring brakes.
To reduce the risk of personal injury or property damage when
manually releasing the spring brakes, be sure to block the wheels
so the vehicle cannot move once the brakes are released.
Towing the vehicle with the front wheels suspended
When it is necessary to tow a vehicle with the front wheels suspended,
extra precautions must be taken to avoid transmission or differential
damage. Proceed as follows:
•Remove the axle shafts from the axle assembly to prevent the wheels
from driving the differential and the transmission.
•The wheel hub ends must be covered to prevent loss of axle lubricant
and entrance of other contaminants. If the axle shafts are not
removed, removal of the driveshaft is required.
+–+–
2008 F-650/750(f67)
Supplement
USA(fus)
Roadside Emergencies
146

Note:To avoid transmission damage, vehicles should not be towed even
a short distance without suspending rear wheels or removing the axle
shaft or driveshaft.
Note:In the event the chassis is equipped with a tandem axle and the
vehicle is to be towed from the front, the forward rear axle may be
raised to clear the road surface and secured to the frame by chains or
U-bolts, allowing only the rear rear axle to contact the road surface. Axle
shafts must be removed from the rear rear axle assembly. The wheel hub
ends must be covered to prevent loss of axle lubricant and entrance of
contaminants. Use extreme care in securing the chains or U-bolts to
avoid possible damage to the brake lines, hoses or other components.
Towing vehicles equipped with a driver-controlled differential lock
Note:If the vehicle must be towed to a service facility with the drive
axle wheels on the ground, it is necessary to remove the axle shafts
before the vehicle is towed.
1. Shift collar in the locked position
2. Actuator assembly and shift fork
3. Axle shaft
4. Interference between the shift
collar and housing
5. Shift collar in the unlocked
position
6. Outer splines - axle shaft to collar
7. Shift collar and differential case
splines
8. Inner splines - axle shaft to side
gear
9. Side gear
10. Differential (plain) case half
Removing axle shafts before towing
1. Shift the main differential to the unlocked (disengaged) position. The
differential lock light will turn off.
2008 F-650/750(f67)
Supplement
USA(fus)
Roadside Emergencies
147

2. Remove the capscrews and washers or stud nuts and washers from
flanges of both axle shafts.
3. Loosen the tapered dowels in the flanges of both axle shafts by
holding a 1
12inch diameter brass drift or hammer against the axle shaft
center and hitting it with a five or six pound hammer.Note:Do not use
a chisel or wedge to loosen the axle shafts and dowels. Use of a chisel or
wedge can damage the hub, axle shafts and oil seals.
4. Remove the tapered dowels and both axle shafts from the axle
assembly.
5. Assemble a cover over openings of both wheels ends to prevent loss of
lubricant and keep dirt away from the wheel bearing cavities.
Note:One of the axle shafts has two sets of splines. One set to engage
with the differential side gear and one set to engage with the shift collar
for the differential lock. It may be necessary to rotate the shaft slightly
to align the gear spline teeth with the shift collar teeth in order to
remove the axle shaft.
Installing the axle shafts
1. Remove the covers from the wheel ends
2. Shift the differential lock to the unlocked position (disengaged)
position.
3. Install the axle shafts
•Place the gaskets on the wheel hub studs.
•Push the right-hand axle shaft and gasket into the wheel end and
housing until the shaft stops against the differential shift collar.
•Push down and in on the axle shaft flange and rotate the shaft until
the splines of the shaft and shift collar are engaged.
•Push the axle shaft further into the housing until the shaft stops
against the differential side gear.
•Push down on the axle shaft flange and rotate the shaft until the
splines of the shaft and side gear are engaged.
•Push the axle shaft completely into the housing until the axle shaft
flange and the gasket are flush against the wheel hub.
•Install the left-hand axle shaft and gasket into the wheel end.
4. If tapered dowels are required, install them at each stud and into the
flange of the axle shaft. Use a punch or drift and hammer, if needed.
5. Install the fasteners and tighten to correct torque value. Refer to the
Service Manual.
2008 F-650/750(f67)
Supplement
USA(fus)
Roadside Emergencies
148