
Starting a diesel engine with the vehicle on a steep grade
When starting a diesel engine when the loaded vehicle is on a grade, the
engine RPM starts to fall slightly when the clutch is engaged; do not
disengage the clutch and try to increase engine RPM as this may damage
driveline components. The engine recovers as the vehicle begins moving.
Cold weather operation
WARNING:Do not use volatile starting aids such as ether,
propane or gasoline in the engine air intake system. Glow plugs
may ignite vapors which can cause engine damage or personal injury.
For best engine operation in temperatures of 32°F (0°C) or lower:
•Make sure the batteries are the correct type and are fully charged.
Check other electrical components to make sure they’re in optimum
condition.
•Use a permanent-type engine coolant to protect the engine against
damage from freezing.
•If your vehicle is equipped with a water-fuel separator, drain it daily.
Fill the fuel tank at the end of daily operation to prevent condensation
in the fuel system.
•Use the proper engine oil and maintain it at its proper level.
•
At temperatures of –4°F (–20°C) or below, it is recommended that you
use a crankcase-mounted coolant heater to improve cold engine starting.
•If operating in arctic temperatures of –20°F (–29°C) or lower, consult
your truck dealer for information about special cold weather
equipment and precautions.
Note:Idling in cold weather does not heat the engine to its normal
operating temperature. Long periods of idling in cold weather can cause
a build-up of heavy deposits of carbon and rust on valve stems causing
them to stick which, in turn, can cause valvetrain damage.
The use of winter fronts, or other air-restrictive devices mounted in front
of the radiator on vehicles with chassis-mounted charge air coolers, are
not recommended unless extremely cold weather conditions exist. Air
flow restriction can cause high exhaust temperatures, power loss,
excessive fan usage and a reduction in fuel economy. If you must use a
winter front, the device should have a permanent opening of at least 120
sq in. (774 sq. cm) directly in line with the fan hub.
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Hot weather operation
•Use a permanent-type engine coolant to protect the engine against
damage from overheating.
•Fill the fuel tank at the end of daily operation to prevent condensation
in the fuel system.
•Keep external surfaces of the engine, radiator, charge air cooler, A/C
condenser and accessories clean to avoid dirt build-up.
•Above normal coolant temperatures could be experienced while
driving in a transmission gear ratio which lugs the engine. To correct
this problem, engine speed should be increased by downshifting into
the next lower gear.
Restarting after running out of fuel
The fuel system may need to be purged of air, refer toRunning out of
fuelin theMaintenance and Specificationschapter.
Engine shutdown (diesel engine only)
Allow the engine to idle for three to five minutes before shutting it
down. The larger the engine, the greater the need for this idling period.
However, do not let the engine idle for more than 10 minutes.
GENERAL OPERATING INSTRUCTIONS
•Start the vehicle in motion by using the highest gear speed in the
transmission that lets the engine easily start the load without slipping
the clutch.
•Accelerate smoothly and evenly; rapid acceleration increases fuel
consumption without increasing engine performance.
•
When approaching a hill, press the accelerator smoothly to start the
incline at full power, then shift down as needed to maintain vehicle speed.
•When going down a hill, or long steep grades, prevent overspeeding of
the engine; normally, choose the same gear to descend the hill that
you use to ascend the hill. The engine governor has no control over
engine speed when it is being pushed by a loaded vehicle.
•Operate in a gear that permits an engine speed not in excess of the
maximum governed speed or high-idle RPM (no load).
•
Always shift to a lower gear at high altitudes to prevent engine smoking.
•Diesel engines:Allow the engine to idle for three to five minutes
before shutting it down; the larger the engine, the greater the need for
this idling period. However, do not let the engine idle for more than
10 minutes.
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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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several transmission upshifts and downshifts; during this learning
process, slightly firmer shifts may occur. After this learning process,
normal shift feel and shift scheduling will resume.
P (Park)
This position locks the transmission and prevents the rear wheels from
turning.
To put your vehicle in gear:
1. Start the engine
2. Press the brake pedal
3. Move the gearshift lever into the desired gear
To put your vehicle in P (Park):
1. Come to a complete stop
2. Move the gearshift lever and securely latch it in P (Park)
WARNING:Always set the parking brake fully and make sure
the gearshift is latched in P (Park). Turn the ignition to the off
position and remove the key whenever you leave your vehicle.
R (Reverse)
With the gearshift lever in R (Reverse), the vehicle will move backward.
Always come to a complete stop before shifting into and out of R
(Reverse).
N (Neutral)
With the gearshift lever in N (Neutral), the vehicle can be started and is
free to roll. Hold the brake pedal down while in this position.
D (Drive)
This is the normal driving position for the best fuel economy. This
position allows automatic upshifts and downshifts through gears one
through six.
4 (Fourth)
This position allows automatic upshifts and downshifts in gears one
through four.
2 (Second)
Use 2 (Second) to start-up on slippery roads or to provide additional
engine braking on downgrades.
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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. These ranges can also
be used to provide additional steps
between transmission shifts when
driving on steep grades and/or fuel
economy may be factors.
Note:Do not shift between ranges
when the speed control is on.
WARNING:Never shift a two-speed axle when descending a
steep grade as this may cause loss of vehicle control and result
in personal injury.
Axle shifting
Manual transmissions
•To downshift,select the next lower gear, release and press the
accelerator pedal rapidly, or while holding the accelerator pedal down,
release and engage the clutch rapidly.Note:The clutch method is
recommended when driving at slower speeds.
•To upshift,keep the accelerator pedal down, select the next higher
gear, release the accelerator and pause until the axle upshifts.Note:
De-clutch for smoother axle upshifts when driving at slower speeds.
Automatic transmissions
•Use LOW when you drive a fully-loaded vehicle on a severe grade or
in congested traffic. To activate LOW, press the upper portion of the
switch.
•Use HIGH for all normal driving conditions with a lightly-loaded or
partially-loaded vehicle. To activate HIGH, press the lower portion of
the switch.
Note:You can’t split-shift with an automatic transmission. Also,
downshifting above 40 mph (64 km/h) may result in transmission or axle
damage.
To shift the axle from LOW to HIGH with the vehicle stopped, place the
transmission in N (Neutral), then press the lower part of the switch.
2SPD
LOW
HIGH
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Fuse/Relay
locationFuse amp
ratingFuse description
15 10A Interior lamp relay
16 15A High beams, Indicator
17 — Not used
18 5A Dimmer switch, Interior lighting
19 15A Engine control (diesel engine only)
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 relay
24 15A Hydraulic brakes relay, Fuel heater relay
(diesel engine only), Air dryer
25 10A Blower motor relay coil
26 10A Right-hand low beam headlight
27 — Not used
28 10A Left-hand low beam headlight
29 10A Cluster, GEM
30 15A Allison electronic transmission
31 15A Mirror fold relay
Relay 1 — Interior lamps
Relay 2 — Not used
Relay 3 — Horn
Relay 4 — Not used
Relay 5 — Not used
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Fuse/Relay
locationFuse amp
ratingFuse description
10 15A Air tank moisture removal valve
11 30A Electric trailer brake
12 20A Passenger compartment fuse box 5 and 21
13 15A Instrument cluster/Gateway module
14 20A Nitrogen oxide sensor (diesel engine only)
15 — Not used
16 5A BendixAir ABS
17 — Not used
18 10A Fuel transfer pump
19 15A Powertrain control module power 1 (gasoline
engine only)
20 10A Powertrain control module power 2 (gasoline
engine only)
21 20A Powertrain control module power 3 (gasoline
engine only)
22 20A Powertrain control module power 4 (gasoline
engine only)
23 — Not used
24 10A Powertrain control module keep-alive power
(gasoline engine only)
101 30A Bendix Air ABS relay (Air brake vehicles
only)
Hydraulic brakes module (Hydraulic brake
vehicles only)
102 20A Ignition switch
103 20A Ignition switch, Passenger compartment fuse
box fuses 19, 29 and 30
104 20A Power point
105 20A Power door lock switches
106 30A Main light switch, Multi-function switch
107 50A Passenger compartment fuse box fuses 1, 2,
3, 4, 12, 13, 14 and 15
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Fuse/Relay
locationFuse amp
ratingFuse description
108 40A Fuel heater (diesel engine only)
20A Fuel pump module (gasoline engine only)
109 40A Power window
110 30A Windshield wiper
111 30A Body builder relay, Parking lamps
112 40A Blower motor
113 30A Heated seats, Air-Ride seat
114 20A Aftertreatment DCU
115 20A Ignition switch, Passenger compartment fuse
box fuses 8, 9, 10 and 11
116 30A Left/Right turn relays, Back-up lamp relay
117 20A Stoplamps
118 60A Hydraulic brake vehicles (Trailer tow package
only)
601 60A Trailer socket
602 60A Air brake trailer tow fuse block
30A Hydraulic brakes pump motor 2
201 — Windshield washer relay
202 — Wiper high/low relay
203 — Wiper run/park relay
204 — Windshield wiper relay
205 — Body builder relay, right turn
206 — Body builder relay, left turn
207 — ABS event relay (Hydraulic brake vehicles
only)
208 — Body builder relay, back-up lamps relay
209 — Auxiliary stoplamp relay
301 — Fuel heater/Fuel transfer pump relay (diesel
engine only)
— Fuel pump module (gasoline engine only)
302 — Body builder relay, parking lamps relay
303 — Blower motor relay
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