Shifting the axle from HI to LO range - vehicle stopped
Place the transmission in N (Neutral), then press the upper part of the
switch.
Note:Do not shift the axle to LO range with the vehicle in motion.
Split-shifting (combined axle and transmission shift - manual
transmissions only)
Split-shift sequence
Ratio
combination1234567891011
Transmission
gear1st 1st 2nd 2nd 3rd 3rd 4th 4th 5th 6th 6th
Axle range LO HI LO HI LO HI LO HI LO LO HI
To downshiftthe axle to a slower ratio and shift the transmission, shift
the transmission and move the control switch to the lower ratio before
the clutch is re-engaged.
To upshiftthe axle and shift the transmission, move the control switch
to a faster ratio and make the transmission shift in the usual manner.
Ratio extender use
Low End
A two-speed axle can be used as a ratio-extender when split shifting is
not necessary. For low end use, just shift the axle into LO to start out,
and shift to HI when the extra torque is no longer needed.
Transmission (5-speed) 1st 1st 2nd 3rd 4th 5th 6th
Two-speed axle Axle low Axle high
High End
To use the two-speed axle as a high end ratio-extender, stay in the LO
range for normal upshifts and only shift the axle to HI on the freeway for
greater road speed.
Transmission
(5-speed)1st 2nd 3rd 4th 5th 6th
Speed
Two-speed axle Low for gradeability Axle high
2008 F-650/750(f67)
Supplement
USA(fus)
Driving
127
Safety chains
Always connect the trailer’s safety chains to the frame or hook retainers
of the vehicle hitch. To connect the trailer’s safety chains, cross the
chains under the trailer tongue and allow slack for turning corners.
If you use a rental trailer, follow the instructions that the rental agency
gives to you.
Do not attach safety chains to the bumper.
Trailer brakes
Electric brakes and manual, automatic or surge-type trailer brakes are
safe if installed properly and adjusted to the manufacturer’s
specifications. The trailer brakes must meet local and Federal
regulations.
Do not connect a trailer’s hydraulic brake system directly to your
vehicle’s brake system. Your vehicle may not have enough
braking power and your chances of having a collision greatly increase.
Trailer lamps
Trailer lamps are required on most towed vehicles. Your vehicle may be
equipped with one of two possible trailer wiring designs. Make sure all
running lights, brake lights, turn signals and hazard lights are working.
See your dealer or trailer rental agency for proper instructions and
equipment for hooking up trailer lamps.
Driving while you tow
When towing a trailer:
•Keep your speed no faster than 70 mph (112 km/h) during the first
500 miles (800 km) of towing a trailer, and don’t make full throttle
starts.
•Turn off the speed control. The speed control may shut off
automatically when you are towing on long, steep grades.
•Consult your local motor vehicle speed regulations for towing a trailer.
•To eliminate excessive transmission shifting, use a lower gear. This will
also assist in transmission cooling.
•Anticipate stops and brake gradually.
•Do not exceed the GCWR rating or transmission damage may occur.
Servicing after towing
If you tow a trailer for long distances, your vehicle will require more
frequent service intervals. Refer to yourScheduled Maintenance Guide
for more information.
2008 F-650/750(f67)
Supplement
USA(fus)
Driving
130
Trailer towing tips
•Practice turning, stopping and backing up before starting on a trip to
get the feel of the vehicle trailer combination. When turning, make
wider turns so the trailer wheels will clear curbs and other obstacles.
•Allow more distance for stopping with a trailer attached.
•If you are driving down a long or steep hill, shift to a lower gear. Do
not apply the brakes continuously, as they may overheat and become
less effective.
•The trailer tongue weight should be 10–15% of the loaded trailer
weight.
•If you will be towing a trailer frequently in hot weather, hilly
conditions, at GCW, or any combination of these factors, consider
refilling your rear axle with synthetic gear lube if not already so
equipped. Refer toLubricant specificationsin theMaintenance and
Specificationschapter for the lubricant specification. Remember that
regardless of the rear axle lube used, do not tow a trailer for the first
500 miles (800 km) of a new vehicle, and that the first 500 miles
(800 km) of towing be done at no faster than 70 mph (112 km/h) with
no full throttle starts.
•After you have traveled 50 miles (80 km), thoroughly check your
hitch, electrical connections and trailer wheel lug nuts.
•To aid in engine/transmission cooling and A/C efficiency during hot
weather while stopped in traffic, place the gearshift lever in P (Park)
(if available on your automatic transmission) or N (Neutral) (manual
transmissions and automatic transmissions withoutaP[Park]
position).
•Vehicles with trailers should not be parked on a grade. If you must
park on a grade, place wheel chocks under the trailer’s wheels.
FIFTH WHEEL OPERATION
Failure to follow the fifth wheel manufacturer’s instructions for
hooking and unhooking as well as sliding the fifth wheel could
result in an accident, personal injury or death.
When the tractor and trailer are parked unattended, the trailer
brake hand control should never be used to apply the brake,
since air may leak from the system, allowing vehicle movement,
resulting in possible property damage, personal injury or death.
2008 F-650/750(f67)
Supplement
USA(fus)
Driving
131
Fuse/Relay
LocationFuse Amp
RatingFuse Description
111 30A** Park lamps relay, Park lamps
112 40A** Blower motor relay, Blower motor
113 30A** Heated seats
114 25A** Hydraulic ABS ECU power
115 20A** Ignition switch, Central Junction Box fuses 8,
9, 10 and 11, Starter motor relay
116 30A** Left/Right turn relays, Back-up lamp relay
117 20A** Stoplamps relay
118 60A** Hydraulic brake vehicles (Trailer tow package
only)
119/120 60A** Hydraulic brake vehicle (Trailer tow package
only)
Air brake vehicles (Trailer tow package only)
121/122 60A** Hydraulic brake, ABS system
Air brake trailer tow fuse block
201 — Washer pump relay
202 — Wiper speed relay
203 — Wiper on/off relay
204 — Wiper power relay
205 — RH stop/turn relay
206 — LH stop/turn relay
207 — Hydraulic ABS event relay
208 — Back-up lamps relay
209 — Stoplamp relay
301 — Fuel heater/Fuel transfer pump relay
302 — Park lamps relay
303 — Blower motor relay
304 — Air ABS relay
Hydraulic modulator relay
* Mini fuse **Maxi fuse
2008 F-650/750(f67)
Supplement
USA(fus)
Roadside Emergencies
140
Running out of fuel
Avoid running out of fuel as this will allow air to enter the fuel system,
which will make restarting the vehicle difficult.
If you have run out of fuel:
•If your vehicle is equipped with dual fuel tanks,add at least 4–5
gallons (15–19 liters) of fuel to each tank before attempting to restart
the engine.
•The fuel system must be primed before attempting to restart the
engine. Refer to the engine operator’s manual for instructions on
priming the engine.
•Use caution not to overheat and damage the starterby cranking
the engine for an excessive period of time. You may need to crank the
engine for a longer time than normal. If the engine fails to start in 30
seconds, turn the ignition to the OFF position and wait for two
minutes before cranking the engine again.
•Any remaining trapped air will self-purge from the fuel system once
the engine starts running.
•The engine may run rough and produce white smoke while air is in
the fuel system. This is normal and should stop after a short period of
time.
FUEL CONSUMPTION IMPROVEMENT MEASURES
There are two important factors you can control to improve fuel
economy: the mechanical condition of your vehicle and how you drive it.
A properly maintained vehicle will deliver better performance than a
neglected vehicle. Always follow your maintenance schedule to keep your
vehicle in top operating condition.
Also, your driving habits have a significant influence on use of fuel. By
following these suggestions, you can stretch your fuel use:
•Avoid changes in speed as much as possible.
•Anticipate changing traffic conditions. Sudden stops and fast
acceleration waste fuel.
•Avoid extensive idling.
•Do not drive with your foot resting on the brake pedal.
2008 F-650/750(f67)
Supplement
USA(fus)
Maintenance and Specifications
178
Diesel particulate filter regeneration (Cummins engine only)
Under most operating conditions, DPF regeneration will be transparent
to the operator. A small increase in engine/turbo sound-level is normal
during filter regeneration. If, however, your engine is operated for
extended periods of time under one of the following conditions, operator
assistance may be required to facilitate the filter regeneration process:
•Vehicle is operated in stop-and-go traffic and/or maintains low speeds
as in a city/delivery driving
•Engine is started and shut-off frequently
•Vehicle payload is relatively light
•Vehicle is regularly operated in cold ambient temperatures (i.e. below
0°F [-18°C])
Diesel Particulate Filter Four–Level Loading Chart
Level/Lamp status Filter status Requested action
Level 1
DPF lamp solidRegeneration required. Drive on highway at
highway speedsOR
started “parked
regeneration” to
prevent loss of engine
performance. Level 2
DPF lamp flashingNearly full. Engine
performance is limited.
Level 3
DPF lamp flashing +
Service Engine Soon
lamp solidFull. Engine is
increasingly limited.Perform “parked
regeneration” to
prevent loss of engine
performance.
Level 4
Stop Engine lamp
solidOver full. Engine
performance is highly
limited. Continued
operation may result
in irreparable damage
to the filter.Pull vehicle safely off
roadway, turn on
hazard flashers and
shut down engine as
soon as possible. Seek
service immediately.
2008 F-650/750(f67)
Supplement
USA(fus)
Maintenance and Specifications
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Air suspension U-bolt checks and re-torquing procedures
1. Inspect the threads of the U-bolt and nut for rust and debris. Clean
the threads if contaminated.
2. Using a torque wrench, determine if any nuts can be turned with a
force below the specified torque.
3. Using the lowest discovered torqued nut as a starting point, retighten
the nuts using the sequence listed underAir suspension U-bolt and
U-bolt nut installation.
Air suspension U-bolt and U-bolt nut installation
1. Inspect the threads of the U-bolt and nut for rust and debris. Clean
the threads if contaminated.
2. Install the U-bolts and nuts and torque the nuts to 15 ft. lb. (20 N•m),
using a diagonal pattern.
3. Re-torque the nuts to 100 ft. lb. (136 N•m), using a diagonal pattern.
4. Re-torque the nuts to 200 ft. lb. (271 N•m), using a diagonal pattern.
5. Re-torque the nuts to 400 ft. lb. (542 N•m), using a diagonal pattern.
(For vehicles equipped with 14ACC, 14 ADN and 14ADP axles, do not
use Step 6.)
6. Re-torque the nuts to 425 ft. lb (576 N•m), using a diagonal pattern.
(For vehicles equipped with 14ACC, 14 ADN and 14ADP axles.)
7. Use the same diagonal pattern with each U-bolt nut re-torque.
Spring U-bolt checks
Check U-bolt nuts and re-torque every 36,000 miles (58,000 km) after
initial 1,000 miles (1,600 km) re-torque. The U-bolt and nut threads and
seats should be cleaned and lubricated to ensure peak condition when
re-torqued.
DRIVESHAFT
At the regular lubrication interval, check the universal joints for any
evidence of wear or looseness. Should driveshaft vibrations occur, stop
the vehicle immediately to avoid possible hazardous consequences or
damage to other components.
REAR AXLE LUBRICANT
Refer to theScheduled Maintenance Guidechapter for rear axle
lubricant level checks and lubricant change intervals.
2008 F-650/750(f67)
Supplement
USA(fus)
Maintenance and Specifications
195