
Driving
Condition LoadTurbo-
charger
Tempera- ture Idle Time
(min.) Be- fore En-
gine Shut- down
Stop and Go Empty Cool Less than
One
Stop and Go Medium
One
Highway Speeds Medium Warm Two
City Traffic Maximum GCWR Three
Highway Speeds Maximum
GCWR Four
Uphill Grade Maximum
GCWR Hot Five
Idle Shutdown
This feature can be enabled so that the truck will auto-
matically shutdown when the truck has been idling for a
set period of time when the engine is at operating
temperature. Idle time can be set in 5 minute increments
between 5 and 60 minutes. See your local authorized
dealer to enable this feature.
Programmable Maximum Vehicle Speed (Chassis
Cab Only)
This feature allows the owner to set a maximum vehicle
speed for the vehicle. The 3500 Series maximum vehicle
speed can be set between 40 mph (64 km/h) and 87 mph
(140 km/h). The 4500/5500 Series maximum vehicle
speed can be set between 40 mph (64 km/h) and 85 mph
(136 km/h). See your local authorized dealer to enable
this feature.
NOTE:
DO NOT set the maximum vehicle speed to a
value greater than what the vehicle tires are rated for.
224 STARTING AND OPERATING

Operating Precautions
Avoid Overheating The Engine
The temperature of the engine coolant (antifreeze) (a
mixture of 50% ethylene-glycol and 50% water) must not
exceed the normal range of the temperature gauge 240°F
(116°C) with a 21 psi (145 kPa) coolant pressure cap.
Usually the engine coolant (antifreeze) temperature indi-
cated during operation will be to the left of center in the
normal range of the gauge.
Avoid Low Coolant Temperature Operation
Continual operation at low engine coolant (antifreeze)
temperature below the normal range on the gauge 140°F
(60°C) can be harmful to the engine. Low engine coolant
(antifreeze) temperature can cause incomplete combus-
tion which allows carbon and varnish to form on pistonrings and injector nozzles. Also, the unburned fuel can
enter the crankcase, diluting the lubricating oil and
causing rapid wear to the engine.
Cooling System Tips — Automatic Transmission
To reduce potential for engine and transmission over-
heating in high ambient temperature conditions, take the
following actions:
•
City Driving —
When stopped, shift the transmission into NEUTRAL
and increase engine idle speed.
• Highway Driving —
Reduce your speed.
• Up Steep Hills —
Select a lower transmission gear.
• Air Conditioning —
Turn it off temporarily.
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STARTING AND OPERATING 225

The automatic transmission will downshift more aggres-
sively in TOW/HAUL mode when the exhaust brake is
enabled to increase brake performance.
CAUTION!
Use of aftermarket exhaust brakes is not recom-
mended and could lead to engine damage
WARNING!
Do not use the exhaust brake feature when driving in
icy or slippery conditions as the increased engine
braking can cause the rear wheels to slide and the
vehicle to swing around with the possible loss of
vehicle control, which may cause an accident possi-
bly resulting in personal injury or death.
NOTE: For optimum braking power it is recommended
to use the exhaust brake while in TOW/HAUL mode. The exhaust brake feature can also be used to reduce the
engine warm up time. To use the exhaust brake as a
warm-up device, the vehicle must be stopped or moving
less than 5 mph (8 km/h), the
Exhaust Brake Indicator
must be on, and the coolant temperature must be below
180°F (82°C) and ambient temperature below 60°F (16°C).
Automatic Smart Exhaust Brake
Automatic Exhaust Brake technology delivers smoother,
less aggressive exhaust braking characteristics during
downhill descents. Although it can apply full exhaust
braking force if needed, Automatic Exhaust Brake may
not apply obvious braking if the vehicle speed is not
increasing. Automatic Exhaust Brake is intended to main-
tain vehicle speed, while Full Exhaust Brake is intended
to reduce vehicle speed.
Automatic Exhaust Brake can be enabled by pushing the
exhaust brake button again anytime after the normal Full
Exhaust Brake has been turned on. The “Exhaust Brake
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STARTING AND OPERATING 229

Indicator” in the EVIC/DID will change from Yellow to
Green when Automatic Exhaust Brake is enabled. Push-
ing the exhaust brake button again will toggle the ex-
haust brake mode to off.
AUTOMATIC TRANSMISSION — IF EQUIPPED
CAUTION!
Damage to the transmission may occur if the follow-
ing precautions are not observed:
•Shift into or out of PARK or REVERSE only after
the vehicle has come to a complete stop.
• Do not shift between PARK, REVERSE, NEU-
TRAL, or DRIVE when the engine is above idle
speed.
• Before shifting into any gear, make sure your foot
is firmly pressing the brake pedal.
WARNING!
• It is dangerous to shift out of PARK or NEUTRAL
if the engine speed is higher than idle speed. If
your foot is not firmly pressing the brake pedal, the
vehicle could accelerate quickly forward or in re-
verse. You could lose control of the vehicle and hit
someone or something. Only shift into gear when
the engine is idling normally and your foot is
firmly pressing the brake pedal.
(Continued)
230 STARTING AND OPERATING

self-calibrating; therefore, the first few shifts on a new
vehicle may be somewhat abrupt. This is a normal
condition, and precision shifts will develop within a few
hundred miles (kilometers).
Only shift from DRIVE to PARK or REVERSE when the
accelerator pedal is released and the vehicle is stopped.
Be sure to keep your foot on the brake pedal when
shifting between these gears.
The transmission shift lever has only PARK, REVERSE,
NEUTRAL, and DRIVE shift positions. Manual down-
shifts can be made using the Electronic Range Select
(ERS) shift control (refer toElectronic Range Select (ERS)
Operation in this section for further information). Press-
ing the ERS (-/+) switches (on the shift lever) while in the
DRIVE position will select the highest available transmis-
sion gear, and will display that gear in the instrument
cluster as 1, 2, 3, etc.Gear Ranges
DO NOT race the engine when shifting from PARK or
NEUTRAL into another gear range.
NOTE: After selecting any gear range, wait a moment to
allow the selected gear to engage before accelerating.
This is especially important when the engine is cold.
PARK (P)
This range supplements the parking brake by locking the
transmission. The engine can be started in this range.
Never attempt to use PARK while the vehicle is in
motion. Apply the parking brake when leaving the
vehicle in this range.
When parking on a level surface, you may shift the
transmission into PARK first, and then apply the parking
brake.
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STARTING AND OPERATING 233

CAUTION!
•Before moving the shift lever out of PARK, you
must turn the ignition switch from the LOCK/OFF
position to the ON/RUN position, and also press
the brake pedal. Otherwise, damage to the shift
lever could result.
• DO NOT race the engine when shifting from
PARK or NEUTRAL into another gear range, as this
can damage the drivetrain.
The following indicators should be used to ensure that
you have engaged the transmission into the PARK posi-
tion:
• When shifting into PARK, pull the shift lever toward
you and move it all the way counterclockwise until it
stops. •
Release the shift lever and make sure it is fully seated
in the PARK gate.
• Look at the transmission gear position display and
verify that it indicates the PARK position.
• With brake pedal released, verify that the shift lever
will not move out of PARK.
REVERSE (R)
This range is for moving the vehicle backward. Shift into
REVERSE only after the vehicle has come to a complete
stop.
NEUTRAL (N)
Use this range when the vehicle is standing for prolonged
periods with the engine running. The engine may be
started in this range. Apply the parking brake and shift
the transmission into PARK if you must leave the vehicle.
236 STARTING AND OPERATING

If the transmission temperature exceeds normal operat-
ing limits, the powertrain controller will modify the
transmission shift schedule and expand the range of
torque converter clutch engagement. This is done to
prevent transmission damage due to overheating.
If the transmission becomes extremely hot or is in danger
of overheating, the “Transmission Temperature Warning
Light” may illuminate and the transmission may operate
differently until the transmission cools down.
NOTE:Use caution when operating a heavily loaded
vehicle at low speeds (such as towing a trailer up a steep
grade, or in stop-and-go traffic) during hot weather. In
these conditions, torque converter slip can impose a
significant additional heat load on the cooling system.
Downshifting the transmission to the lowest possible
gear (when climbing a grade), or shifting to NEUTRAL
(when stopped in heavy traffic) can help to reduce this
excess heat generation. During cold temperatures, transmission operation may
be modified depending on engine and transmission
temperature as well as vehicle speed. This feature im-
proves warm up time of the engine and transmission to
achieve maximum efficiency. Engagement of the torque
converter clutch is inhibited until the transmission fluid
is warm (refer to the “Note” under “Torque Converter
Clutch” in this section). On Pickup models with 68RFE
transmission, top overdrive gear is also inhibited until
the transmission fluid is warm, and during extremely
cold temperatures (-16°F [-27°C] or below), operation
may briefly be limited to first and direct gears only. On
trucks with AS69RC transmission, fifth and sixth gears
may be inhibited briefly on cold starts below 41°F (5°C),
and during very cold temperatures (-4°F [-20°C] or
below), operation may briefly be limited to third gear
only. During this condition, the ability of the vehicle to
238 STARTING AND OPERATING

accelerate under heavily loaded conditions may be re-
duced. In all cases, normal operation will resume once
the transmission temperature has risen to a suitable level.
Transmission Limp Home Mode
Transmission function is monitored electronically for
abnormal conditions. If a condition is detected that could
result in transmission damage, Transmission Limp Home
Mode is activated. In this mode, the transmission remains
in fourth gear (for 68RFE transmission) or third gear (for
AS69RC transmission) regardless of which forward gear
is selected. If an AS69RC-equipped truck enters Limp
Home Mode at highway speeds, it will initially engage
fifth gear, until the vehicle slows to a speed where third
gear can be engaged. PARK, REVERSE, and NEUTRAL
will continue to operate. The Malfunction Indicator Light
(MIL) may be illuminated. Limp Home Mode allows the
vehicle to be driven to an authorized dealer for service
without damaging the transmission.In the event of a momentary problem, the transmission
can be reset to regain all forward gears by performing the
following steps:
1. Stop the vehicle.
2. Shift the transmission into PARK.
3. Turn the ignition switch to the OFF position.
4. Wait approximately 10 seconds.
5. Restart the engine.
6. Shift into the desired gear range. If the problem is no
longer detected, the transmission will return to normal
operation.
NOTE: Even if the transmission can be reset, we recom-
mend that you visit your authorized dealer at your
earliest possible convenience. Your authorized dealer has
diagnostic equipment to determine if the problem could
recur.
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STARTING AND OPERATING 239