Page 132 of 273

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
Page 138 of 273
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
137
Page 139 of 273
To reduce risk of electrical shock, always replace the cover to
the Power Distribution Box before reconnecting the battery or
refilling fluid reservoirs.
Fuse/Relay
LocationFuse Amp
RatingFuse Description
1 15A* Main light switch
2 30A* Power seat (driver)
3 30A* Power seat (passenger)
4 15A* Washer pump relay, Washer pump motor
5 — Not used
6 15A* Air intake heater (Caterpillar engine only)
7 15A* Stoplamp switches (Air brake vehicles only)
8 25A* Fuel heater relay (Caterpillar
engine-equipped vehicles with dual fuel tanks
only)
9 20A* Inhibit relay, Engine ECM, Cluster,
Transmission TCM
10 15A* Heated drain valve
11 30A* Electric trailer brake
2008 F-650/750(f67)
Supplement
USA(fus)
Roadside Emergencies
138
Page 142 of 273
Trailer tow relays (if equipped)
Fuse/Relay
LocationFuse Amp
RatingDescription
1 30A* Trailer tow ABS feed
2 30A* Trailer tow park/marker lamps
3 30A* Trailer tow stop lamps
4 30A* Trailer tow turn/stop lamps (combined)
Trailer tow turn lamps (separate)
5 — Not used
R1 — Trailer tow ABS relay
R2 — Trailer tow marker lamp relay
R3 — Trailer tow stop lamp relay
R4 — Trailer tow tail lamp relay
R5 — Not used
R6 — Not used
R7 — Trailer tow left turn lamp relay
R8 — Trailer tow right turn lamp relay
*Maxi fuse
Inline fuses
Your vehicle has two inline fuses located in/on the battery cables by the
battery. A 10A fuse for the transmission control module and a 40A fuse
2008 F-650/750(f67)
Supplement
USA(fus)
Roadside Emergencies
141
Page 143 of 273

for the engine control module. Refer toAutomatic transmission
operationin theDrivingchapter andBatteryin theMaintenance and
Specificationschapter for more information.
JUMP STARTING
The gases around the battery can explode if exposed to flames,
sparks, or lit cigarettes. An explosion could result in injury or
vehicle damage.
Batteries contain sulfuric acid which can burn skin, eyes and
clothing, if contacted.
Do not attempt to push-start your automatic transmission
vehicle. Automatic transmissions do not have push-start
capability. Attempting to push-start a vehicle with an automatic
transmission may cause transmission damage.
Before connecting a fast-charger, booster battery or installing a new
battery, make sure the ground polarities of the fast-charger, booster
battery or alternator (when installing a battery) are matched to the
ground polarity of the vehicle battery. Improper usage of the
fast-charger, hook-up of booster battery or installation of a new battery
can cause damage to the electrical system or to the alternator. Do not
attempt to polarize the alternator.
Preparing your vehicle
1.Use only a 12–volt supply to start your vehicle.Do not attach the
jumper cables to the glow plug relay as this could severely damage the
glow plugs, injector driver module and PCM.
2. Do not disconnect the battery of the disabled vehicle as this could
damage the vehicle’s electrical system.
3. Park the booster vehicle close to the hood of the disabled vehicle
making sure the two vehiclesdo nottouch. Set the parking brake on
both vehicles and stay clear of the engine cooling fan and other moving
parts.
4. Check all battery terminals and remove any excessive corrosion before
you attach the battery cables. Ensure that vent caps are tight and level.
5. Turn the heater fan on in both vehicles to protect from any electrical
surges. Turn all other accessories off.
2008 F-650/750(f67)
Supplement
USA(fus)
Roadside Emergencies
142
Page 147 of 273

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
Page 148 of 273

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
Page 150 of 273
Towing the vehicle with the rear wheels suspended
Note:To avoid damage to the cab roof or air deflector when towing the
vehicle backward (rear wheels suspended) the air deflector must be
removed.
Whenever possible, it is preferable to tow a disabled vehicle from the
rear by raising the rear of the chassis. When towing a vehicle with the
rear of the chassis suspended the front wheels must be locked in the
straight-ahead position.
Vehicles equipped with a manual transmission must have at least 1.0 pint
(0.5L) of transmission fluid drained from the case. This will prevent the
transmission fluid from entering the clutch housing and fluid saturating
the clutch discs. Make sure that the transmission fluid is replaced before
the vehicle is returned to service.
2008 F-650/750(f67)
Supplement
USA(fus)
Roadside Emergencies
149