heating Ram 3500 Chassis Cab 2020 User Guide

210STARTING AND OPERATING
If the transmission temperature exceeds
normal operating 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 over -
heating.
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 addi -
tional heat load on the cooling system. Down -
shifting 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 opera
-
tion may be modified depending on engine and
transmission temperature as well as vehicle
speed. This feature improves warm up time of
the engine and transmission to achieve
maximum efficiency. Engagement of the torque
converter clutch is inhibited until the transmis -
sion fluid is warm (refer to the “Note” under
“Torque Converter Clutch” in this section).
On trucks with AS66RC or AS69RC transmis -
sion, 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 accelerate under heavily loaded
conditions may be reduced. 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 electroni -
cally for abnormal conditions. If a condition is
detected that could result in transmission
damage, Transmission Limp Home Mode is acti -
vated. In this mode, the transmission remains
in third gear (for AS66RC/AS69RC transmis -
sion) regardless of which forward gear is
selected. If an AS66RC/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 trans
-
mission 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 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 trans -
mission will return to normal operation.

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212STARTING AND OPERATING
Overdrive Operation
The automatic transmission includes an elec -
tronically controlled Overdrive (FIFTH and SIXTH
gears). The transmission will automatically shift
into Overdrive if the following conditions are
present:
The gear selector is in the DRIVE position.
The transmission fluid has reached an
adequate temperature.
The engine coolant has reached an adequate
temperature.
Vehicle speed is sufficiently high.
The TOW/HAUL switch has not been
activated.
The driver is not heavily pressing the
accelerator.
Torque Converter Clutch
A feature designed to improve fuel economy
has been included in the automatic transmis -
sion on your vehicle. A clutch within the torque
converter engages automatically at calibrated
speeds. This may result in a slightly different feeling or response during normal operation in
the upper gears. When the vehicle speed drops
or during some accelerations, the clutch auto
-
matically disengages.
NOTE:
The torque converter clutch will not engage,
until the transmission fluid and engine
coolant are warm (usually after 1 to 3 miles
(2 to 5 km) of driving). Because engine speed
is higher when the torque converter clutch is
not engaged, it may seem as if the transmis -
sion is not shifting properly when cold. This is
normal. Using the Electronic Range Select
(ERS) shift control, when the transmission is
sufficiently warm, will demonstrate that the
transmission is able to shift into and out of
Overdrive.
If the vehicle has not been driven for several
days, the first few seconds of operation after
shifting the transmission into gear may seem
sluggish. This is due to the fluid partially
draining from the torque converter into the
transmission. This condition is normal and
will not cause damage to the transmission.
The torque converter will refill within five
seconds after starting the engine.
When To Use TOW/HAUL Mode
When driving in hilly areas, towing a trailer,
carrying a heavy load, etc., and frequent trans -
mission shifting occurs, push the TOW/HAUL
switch to activate TOW/HAUL mode. This will
improve performance and reduce the potential
for transmission overheating or failure due to
excessive shifting. When operating in TOW/
HAUL mode, transmission upshifts are delayed,
and the transmission will automatically down -
shift (for engine braking) when the throttle is
closed and/or during steady braking maneu -
vers.

TOW/HAUL Switch

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218STARTING AND OPERATING
When to Use TOW/HAUL Mode
When driving in hilly areas, towing a trailer,
carrying a heavy load, etc., and frequent trans -
mission shifting occurs, push the TOW/HAUL
switch to activate TOW/HAUL mode. This will
improve performance and reduce the potential
for transmission overheating or failure due to
excessive shifting.

TOW/HAUL Switch

The “TOW/HAUL Indicator Light” will illuminate
in the instrument cluster to indicate that TOW/
HAUL mode has been activated. Pushing the
switch a second time restores normal opera -
tion. Normal operation is always the default at
engine start-up. If TOW/HAUL mode is desired,
the switch must be pushed each time the
engine is started.
AUXILIARY SWITCHES — IF EQUIPPED
There can be up to six auxiliary switches located
in the lower switch bank of the instrument panel
which can be used to power various electronic
devices and PTO (Power Take Off) – If Equipped.
If Power Take Off is equipped, it will take the
place of the sixth Auxiliary switch. Connections
to the switches are found under the hood in the
connectors attached to the auxiliary Power
Distribution Center. You have the ability to configure the function
-
ality of the auxiliary switches via the instrument
cluster display. All switches can now be config -
ured for setting the switch type operation to
latching or momentary, power source of either
battery or ignition, and ability to hold last state
across key cycles.
NOTE:
Holding last state conditions are met when
switch type is set to latching and power source
is set to ignition.
For further information on using the auxiliary
switches, please refer to the Ram Body Builders
Guide by accessing www.rambodybuilder.com
and choosing the appropriate links.
FOUR-WHEEL DRIVE OPERATION — IF
EQUIPPED
Four-wheel drive trucks are equipped with
either a manually shifted transfer case or an
electronically shifted transfer case. Refer to the
operating instructions for your transfer case,
located in this section for further information.
WARNING!
Do not use the “TOW/HAUL” feature when
driving in icy or slippery conditions. 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
possibly resulting in personal injury or death.

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272STARTING AND OPERATING
(Continued)
3. Stop filling the DEF tank immediately when any of the following happen: DEF stops
flowing from the fill bottle into the DEF tank,
DEF splashes out the filler neck, or a DEF
pump nozzle automatically shuts off.
4. Reinstall cap onto DEF tank. Filling The Def Tank In Cold Climates
Since DEF will begin to freeze at 12°F (-11°C),
your vehicle is equipped with an automatic DEF
heating system. This allows the DEF injection
system to operate properly at temperatures
below 12°F (-11°C). If your vehicle is not in
operation for an extended period of time with
temperatures below 12°F (-11°C), the DEF in
the tank may freeze. If the tank is overfilled and
freezes, it could be damaged. Therefore, do not
overfill the DEF tank.

Extra care should be taken when filling with
portable containers to avoid overfilling. Note the
level of the DEF gauge in your instrument cluster.
You may safely add a maximum of 2 gallons
(7.5 liters) of DEF from portable containers when
your DEF gauge is reading ½ full.

CAUTION!
To avoid DEF spillage, and possible
damage to the DEF tank from overfilling, do
not “top off” the DEF tank after filling.
DO NOT OVERFILL. DEF will freeze below
12ºF (-11ºC). The DEF system is designed
to work in temperatures below the DEF
freezing point, however, if the tank is over
-
filled and freezes, the system could be
damaged.
When DEF is spilled, clean the area imme -
diately with water and use an absorbent
material to soak up the spills on the ground.
Do not attempt to start your engine if DEF is
accidentally added to the diesel fuel tank
as it can result in severe damage to your
engine, including but not limited to failure
of the fuel pump and injectors.
Never add anything other than DEF to the
tank – especially any form of hydrocarbon
such as diesel fuel, fuel system additives,
gasoline, or any other petroleum-based
product. Even a very small amount of these,
less than 100 parts per million or less than
1 oz. per 78 gallons (295 liters) will contam -
inate the entire DEF system and will require
replacement. If owners use a container,
funnel or nozzle when refilling the tank, it
should either be new or one that is has only
been used for adding DEF. Mopar provides
an attachable nozzle with its DEF for this
purpose.
CAUTION! (Continued)

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STARTING AND OPERATING285
Automatic Transmission
The DRIVE range can be selected when towing.
The transmission controls include a drive
strategy to avoid frequent shifting when towing.
However, if frequent shifting does occur while in
DRIVE, select TOW/HAUL mode or select a lower
gear range (using the Electronic Range Select
(ERS) shift control).
NOTE:
Using TOW/HAUL mode or selecting a lower
gear range (using the ERS shift control) while
operating the vehicle under heavy loading
conditions will improve performance and
extend transmission life by reducing excessive
shifting and heat build up. This action will also
provide better engine braking.
Six-Speed Automatic Transmission Only
When towing a loaded trailer up steep grades at
low speeds (20 mph [32 km/h] or below),
holding your vehicle in first gear (using the ERS
shift control) can help to avoid transmission
overheating. If you regularly tow a trailer for more than
45 minutes of continuous operation, then
change the automatic transmission fluid and
filter(s) as specified for "police, taxi, fleet, or
frequent trailer towing." Refer to the “Mainte
-
nance Plan” for the proper maintenance inter -
vals.
NOTE:
Check the automatic transmission fluid level
before towing (Six-speed automatic only).
Tow/Haul Mode
To reduce potential for automatic transmission
overheating, activate TOW/HAUL mode when
driving in hilly areas, or select a lower gear
range (using the Electronic Range Select (ERS)
shift control) on more severe grades.
Speed Control — If Equipped
Do not use on hilly terrain or with heavy
loads.
When using the Speed Control, if you experi -
ence speed drops greater than 10 mph
(16 km/h), disengage until you can get back
to cruising speed.
Use Speed Control in flat terrain and with
light loads to maximize fuel efficiency.
Cooling System
To reduce potential for engine and transmission
overheating, take the following actions:
City Driving
In city traffic — while stopped, place the trans -
mission in NEUTRAL, but do not increase
engine idle speed.
Highway Driving
Reduce speed.
Temporarily turn off air conditioning.
5

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STARTING AND OPERATING287
Vehicle front end wheel alignment was set to
specifications at the factory without consider -
ation for the weight of the plow. Front end toe-in
should be checked and reset if necessary at the
beginning and end of the snowplow season.
This will help prevent uneven tire wear.
The blade should be lowered whenever the
vehicle is parked.
Maintain and operate your vehicle and snow -
plow equipment following the recommenda -
tions provided by the specific snowplow
manufacturer.
Over The Road Operation With Snowplow
Attached
The blade restricts air flow to the radiator and
causes the engine to operate at higher than
normal temperatures. Therefore, when trans -
porting the plow, angle the blade completely
and position it as low as road or surface condi -
tions permit. Do not exceed 40 mph (64 km/h).
The operator should always maintain a safe
stopping distance and allow adequate passing
clearance.
Operating Tips
Under ideal snow plowing conditions, 20 mph
(32 km/h) should be maximum operating
speed. The operator should be familiar with the
area and surface to be cleaned. Reduce speed
and use extreme caution when plowing unfa -
miliar areas or under poor visibility.
General Maintenance
Snowplows should be maintained in accor -
dance with the plow manufacturer's instruc -
tions.
Keep all snowplow electrical connections and
battery terminals clean and free of corrosion.
When plowing snow, to avoid transmission and
drivetrain damage, the following precautions
should be observed.
Operate with transfer case in 4LO when
plowing small or congested areas where
speeds are not likely to exceed 15 mph
(24 km/h). At higher speeds operate in 4HI.
Vehicles with automatic transmissions
should use 4LO range when plowing deep or
heavy snow for extended periods of time to
avoid transmission overheating.
Do not shift the transmission unless the
engine has returned to idle and wheels have
stopped. Make a practice of stepping on the
brake pedal while shifting the transmission.
5

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IN CASE OF EMERGENCY321
2. Connect the opposite end of the positive (+)
jumper cable to the positive (+) post of the
booster battery.
3. Connect the negative (-) end of the jumper
cable to the negative (-) post of the booster
battery.
4. Connect the opposite end of the negative (-)
jumper cable to a good engine ground
(exposed metal part of the discharged
vehicle’s engine) away from the battery and
the fuel injection system.
5. Start the engine in the vehicle that has the booster battery, let the engine idle a few
minutes, and then start the engine in the
vehicle with the discharged battery. 6. Once the engine is started, remove the
jumper cables in the reverse sequence.
Disconnecting The Jumper Cables

1. Disconnect the negative
(-)
end of the
jumper cable from the engine ground of
the vehicle with the discharged battery.

2. Disconnect the opposite end of the negative (-) jumper cable from the negative (-) post of
the booster battery.
3. Disconnect the positive (+) end of the
jumper cable from the positive (+) post of
the booster battery.
4. Disconnect the opposite end of the positive (+) jumper cable from the positive (+) post
of the vehicle with the discharged battery. If frequent jump starting is required to start your
vehicle you should have the battery and
charging system inspected at an authorized
dealer.
IF YOUR ENGINE OVERHEATS
In any of the following situations, you can
reduce the potential for overheating by taking
the appropriate action.
On the highways — slow down.
In city traffic — while stopped, place the trans
-
mission in NEUTRAL, but do not increase the
engine idle speed while preventing vehicle
motion with the brakes.
WARNING!
Do not connect the jumper cable to the
negative (-) post of the discharged battery.
The resulting electrical spark could cause the
battery to explode and could result in
personal injury. Only use the specific ground
point, do not use any other exposed metal
parts.
CAUTION!
Do not connect jumper cable to any of the
fuses on the positive battery terminal. The
resulting electrical current will blow the fuse.
CAUTION!
Accessories plugged into the vehicle power
outlets draw power from the vehicle’s battery,
even when not in use (i.e., cellular devices,
etc.). Eventually, if plugged in long enough
without engine operation, the vehicle’s
battery will discharge sufficiently to degrade
battery life and/or prevent the engine from
starting.
6

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IN CASE OF EMERGENCY325
NOTE:
For trucks equipped with an 8–speed trans -
mission, shifts between DRIVE and REVERSE
can only be achieved at wheel speeds of
5 mph (8 km/h) or less. Whenever the trans -
mission remains in NEUTRAL (N) for more
than two seconds, you must press the brake
pedal to engage DRIVE or REVERSE.
Push the “ESC OFF” switch, to place the Elec -
tronic Stability Control (ESC) system in
“Partial Off” mode, before rocking the
vehicle. Refer to “Electronic Brake Control
System” in “Safety” for further information.
Once the vehicle has been freed, push the
“ESC OFF” switch again to restore “ESC On”
mode.
WARNING!
Fast spinning tires can be dangerous. Forces
generated by excessive wheel speeds may
cause damage, or even failure, of the axle
and tires. A tire could explode and injure
someone. Do not spin your vehicle's wheels
faster than 30 mph (48 km/h) or for longer
than 30 seconds continuously without
stopping when you are stuck and do not let
anyone near a spinning wheel, no matter
what the speed.
CAUTION!
Racing the engine or spinning the wheels
may lead to transmission overheating and
failure. Allow the engine to idle with the
transmission in NEUTRAL for at least one
minute after every five rocking-motion
cycles. This will minimize overheating and
reduce the risk of transmission failure
during prolonged efforts to free a stuck
vehicle.
When “rocking” a stuck vehicle by shifting
between DRIVE and REVERSE, do not spin
the wheels faster than 15 mph (24 km/h), or drivetrain damage may result.
Revving the engine or spinning the wheels
too fast may lead to transmission over -
heating and failure. It can also damage the
tires. Do not spin the wheels above 30 mph
(48 km/h) while in gear (no transmission
shifting occurring).
6

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SERVICING AND MAINTENANCE363
NOTE:
Intentional tampering with emissions control
systems can result in civil penalties being
assessed against you.
In unusual situations involving grossly malfunc -
tioning engine operation, a scorching odor may
suggest severe and abnormal catalyst over -
heating. If this occurs, stop the vehicle, turn off
the engine and allow it to cool. Service,
including a tune-up to manufacturer's specifica-
tions, should be obtained immediately.
To minimize the possibility of catalytic converter
damage:
Do not interrupt the ignition when the trans -
mission is in gear and the vehicle is in
motion.
Do not try to start the vehicle by pushing or
towing the vehicle.
Do not idle the engine with any ignition
components disconnected or removed, such
as when diagnostic testing, or for prolonged
periods during very rough idle or malfunc -
tioning operating conditions.
Cooling System Engine Coolant Checks
Check the engine coolant (antifreeze) protec-
tion every 12 months (before the onset of
freezing weather, where applicable). If the
engine coolant (antifreeze) is dirty or rusty in
appearance, the system should be drained,
flushed and refilled with fresh coolant. Check
the front of the A/C condenser (if equipped) or
radiator for any accumulation of bugs, leaves,
etc. If dirty, clean by gently spraying water from
a garden hose vertically down the face of the A/
C condenser (if equipped) or the back of the
radiator core.
Check the engine cooling system hoses for
brittle rubber, cracking, tears, cuts and tight-
ness of the connection at the coolant recovery
bottle and radiator. Inspect the entire system
for leaks.
DO NOT REMOVE THE COOLANT PRESSURE CAP
WHEN THE COOLING SYSTEM IS HOT. WARNING!
You or others can be badly burned by hot
engine coolant (antifreeze) or steam from
your radiator. If you see or hear steam
coming from under the hood, do not open
the hood until the radiator has had time to
cool. Never open a cooling system pressure
cap when the radiator or coolant bottle is
hot.
Keep hands, tools, clothing, and jewelry
away from the radiator cooling fan when
the hood is raised. The fan starts automati -
cally and may start at any time, whether the
engine is running or not.
When working near the radiator cooling fan,
disconnect the fan motor lead or turn the
ignition to the OFF mode. The fan is
temperature controlled and can start at any
time the ignition is in the ON mode.7

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382SERVICING AND MAINTENANCE
Tires — General Information
Tire Pressure
Proper tire inflation pressure is essential to the
safe and satisfactory operation of your vehicle.
Four primary areas are affected by improper tire
pressure:
Safety
Fuel Economy
Tread Wear
Ride Comfort and Vehicle Stability Safety
Both underinflation and overinflation affect the
stability of the vehicle and can produce a feeling
of sluggish response or over responsiveness in
the steering.
NOTE:
Unequal tire pressures from side to side may
cause erratic and unpredictable steering
response.
Unequal tire pressure from side to side may
cause the vehicle to drift left or right.
Fuel Economy
Underinflated tires will increase tire rolling
resistance resulting in higher fuel consumption.
Tread Wear
Improper cold tire inflation pressures can cause
abnormal wear patterns and reduced tread life,
resulting in the need for earlier tire replace -
ment.
Ride Comfort And Vehicle Stability
Proper tire inflation contributes to a comfort -
able ride. Overinflation produces a jarring and
uncomfortable ride.
WARNING!
Overloading of your tires is dangerous.
Overloading can cause tire failure, affect
vehicle handling, and increase your stopping
distance. Use tires of the recommended load
capacity for your vehicle. Never overload
them.WARNING!
Improperly inflated tires are dangerous and
can cause collisions.
Underinflation increases tire flexing and
can result in overheating and tire failure.
Overinflation reduces a tire's ability to
cushion shock. Objects on the road and
chuckholes can cause damage that result
in tire failure.
Overinflated or underinflated tires can
affect vehicle handling and can fail
suddenly, resulting in loss of vehicle
control.
Unequal tire pressures can cause steering
problems. You could lose control of your
vehicle.
Unequal tire pressures from one side of the
vehicle to the other can cause the vehicle
to drift to the right or left.
Always drive with each tire inflated to the
recommended cold tire inflation pressure.

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