2020 Ram 3500 check engine light

210SAFETY
The best protection against carbon monoxide
entry into the vehicle body is a properly
maintained engine exhaust system.
Whenever a change is noticed in the sound of
the exhaust system, when exhaust fumes can
be detected inside the vehicle, or when the
underside or rear of the vehicle is damaged,
have a competent mechanic inspect the
complete exhaust system and adjacent body
areas for broken, damaged, deteriorated, or
mispositioned parts. Open seams or loose
connections could permit exhaust fumes to
seep into the passenger compartment. In
addition, inspect the exhaust system each time
the vehicle is raised for lubrication or oil
change. Replace as required.
SAFETY CHECKS YOU SHOULD MAKE
I
NSIDE THE VEHICLE
Seat Belts
Inspect the seat belt system periodically,
checking for cuts, frays, and loose parts.
Damaged parts must be replaced immediately.
Do not disassemble or modify the system.
Front seat belt assemblies must be replaced
after a collision. Rear seat belt assemblies must
be replaced after a collision if they have been
damaged (i.e., bent retractor, torn webbing,
etc.). If there is any question regarding seat belt
or retractor condition, replace the seat belt.
Air Bag Warning Light
The Air Bag warning light will turn on for four
to eight seconds as a bulb check when the
ignition switch is first turned to ON/RUN. If the
light is either not on during starting, stays on, or
turns on while driving, have the system
inspected at an authorized dealer as soon as
possible. After the bulb check, this light will
illuminate with a single chime when a fault with the Air Bag System has been detected. It will
stay on until the fault is removed. If the light
comes on intermittently or remains on while
driving, have an authorized dealer service the
vehicle immediately.
Refer to “Occupant Restraint Systems” in
“Safety” for further information.
Defroster
Check operation by selecting the defrost mode
and place the blower control on high speed. You
should be able to feel the air directed against
the windshield. See an authorized dealer for
service if your defroster is inoperable.
Floor Mat Safety Information
Always use floor mats designed to fit your
vehicle. Only use a floor mat that does not
interfere with the operation of the accelerator,
brake or clutch pedals. Only use a floor mat that
is securely attached using the floor mat
fasteners so it cannot slip out of position and
interfere with the accelerator, brake or clutch
pedals or impair safe operation of your vehicle
in other ways.
If it is necessary to sit in a parked vehicle
with the engine running, adjust your
heating or cooling controls to force outside
air into the vehicle. Set the blower at high
speed.
WARNING!
(Continued)

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SAFETY211
(Continued)
(Continued)
(Continued)
WARNING!
An improperly attached, damaged, folded, or
stacked floor mat, or damaged floor mat
fasteners may cause your floor mat to
interfere with the accelerator, brake, or clutch
pedals and cause a loss of vehicle control. To
prevent SERIOUS INJURY or DEATH:
ALWAYS securely attach your floor mat
using the floor mat fasteners. DO NOT
install your floor mat upside down or turn
your floor mat over. Lightly pull to confirm
mat is secured using the floor mat
fasteners on a regular basis.
ALWAYS REMOVE THE EXISTING FLOOR
MAT FROM THE VEHICLE before
installing any other floor mat. NEVER install
or stack an additional floor mat on top of an
existing floor mat.
ONLY install floor mats designed to fit your
vehicle. NEVER install a floor mat that
cannot be properly attached and secured to
your vehicle. If a floor mat needs to be
replaced, only use a FCA approved floor
mat for the specific make, model, and year
of your vehicle.
ONLY use the driver’s side floor mat on the
driver’s side floor area. To check for inter -
ference, with the vehicle properly parked
with the engine off, fully depress the accel -
erator, the brake, and the clutch pedal (if
present) to check for interference. If your
floor mat interferes with the operation of
any pedal, or is not secure to the floor,
remove the floor mat from the vehicle and
place the floor mat in your trunk.
WARNING! (Continued)
ONLY use the passenger’s side floor mat on
the passenger’s side floor area.
ALWAYS make sure objects cannot fall or
slide into the driver’s side floor area when
the vehicle is moving. Objects can become
trapped under accelerator, brake, or clutch
pedals and could cause a loss of vehicle
control.
NEVER place any objects under the floor
mat (e.g., towels, keys, etc.). These objects
could change the position of the floor mat
and may cause interference with the accel -
erator, brake, or clutch pedals.
If the vehicle carpet has been removed and
re-installed, always properly attach carpet
to the floor and check the floor mat
fasteners are secure to the vehicle carpet.
Fully depress each pedal to check for inter -
ference with the accelerator, brake, or
clutch pedals then re-install the floor mats.
WARNING! (Continued)
4

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220STARTING AND OPERATING
5. After engine start-up, check to see that
there is oil pressure.
6. Release the parking brake and drive.
NOTE:
Engine idle speed will automatically increase
to 1,000 RPM and engage the Variable
Geometry Turbocharger at low coolant
temperatures to improve engine warm-up.
The engine will not automatically crank after
the engine “Wait To Start” telltale goes off if
a door or the hood is ajar.

If the engine stalls, or if the ignition switch is
left ON for more than two minutes after the
“Wait To Start” telltale goes out, reset the
intake air heater by turning the ignition switch
to the OFF position for at least 5 seconds and
then back ON. Repeat steps 1 through 7 of
“Keyless Enter-N-Go Starting Procedure –
Engine Manifold Air Temperature Below 66° F
(19° C).”

EXTREME COLD WEATHER
The Cummins® Turbo Diesel engine is
equipped with several features designed to
assist cold weather starting and operation:
The engine block heater is a resistance
heater installed in the water jacket of the
engine just above and behind the oil filter. It
requires a 110–115 Volt AC electrical outlet
with a grounded, three-wire extension cord.
NOTE:
The engine block heater cord is a factory
installed option. If your vehicle is not equipped,
heater cords are available from an authorized
Mopar dealer.
A 12 Volt heater built into the fuel filter hous -
ings aid in preventing fuel gelling. It is
controlled by a built-in thermostat.
A intake air heater system both improves
engine starting and reduces the amount of
white smoke generated by a warming engine.
NORMAL STARTING PROCEDURE —
E
NGINE MANIFOLD AIR TEMPERATURE
A
BOVE 66° F (19° C)
Observe the instrument panel cluster lights
when starting the engine.

1. Always apply the parking brake.

2. Shift into PARK for an automatic
transmission.
3. Place the ignition switch in the ON position and watch the instrument panel cluster
lights.
4. Place the ignition switch in the START position and crank the engine. Do not press
the accelerator during starting.
CAUTION!
If the “Water in Fuel Indicator Light” remains
on, DO NOT START the engine before you
drain the water from the fuel filters to avoid
engine damage. Refer to “Draining Fuel/
Water Separator Filter” in “Servicing And
Maintenance” for further information.

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STARTING AND OPERATING221
5. Check that the oil pressure warning light
has turned off.
6. Release the parking brake.
STARTING PROCEDURE — ENGINE
M
ANIFOLD AIR TEMPERATURE 0°F TO
66°F (–18°C
TO 19°C)
NOTE:
The temperature displayed in the instrument
cluster does not necessarily reflect the engine
manifold air temperature. Refer to “Instrument
Cluster Display” in “Getting To Know Your
Instrument Panel” for further information.
When engine temperatures fall below 66°F
(19°C) the “Wait To Start Light” will remain on
indicating the intake air heater system is active. Follow the steps in the “Normal Starting”
procedure except:

1. The “Wait To Start” telltale will remain on
for a period of time that varies depending
on the engine temperature.

2. While the “Wait To Start” telltale is on, the instrument cluster will additionally display a
gauge or bar whose initial length represents
the full “Wait To Start” time period. Its
length will decrease until it disappears
when the “Wait To Start” time has elapsed.
3. After the “Wait To Start” telltale goes off, place the ignition switch in the START
position. Do not press the accelerator
during starting. 4. After engine start-up, check that the oil
pressure warning light has turned off.
5. Release the parking brake and drive.
NOTE:
Engine idle speed will automatically increase
to 1,000 RPM and engage the Variable
Geometry Turbocharger at low coolant
temperatures to improve engine warm-up.
Automatic equipped vehicles with optional
Keyless Enter-N-Go – If the start button is
pushed once while in park with the ignition
off and driver’s foot on the brake pedal, the
vehicle will automatically crank and start
after the Wait to Start time has elapsed. If it
is desired to abort the start process before it
completes, the driver’s foot should be fully
CAUTION!

Do not crank engine for more than 25 seconds
at a time or starter motor damage may result.
Turn the ignition switch to the OFF position and
wait at least two minutes for the starter to cool
before repeating start procedure.

CAUTION!
If the “Water in Fuel Indicator Light” remains
on, DO NOT START the engine before you
drain the water from the fuel filters to avoid
engine damage. Refer to “Draining Fuel/
Water Separator Filter” in “Servicing And
Maintenance” for further information.
CAUTION!

Do not crank engine for more than 25 seconds
at a time or starter motor damage may result.
Turn the ignition switch to the OFF position and
wait at least two minutes for the starter to cool
before repeating start procedure.

5

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STARTING AND OPERATING227
DECEL switch and the idle speed will
decrease to approximately 1,100 RPM.
3. To cancel the Idle–Up feature, either push the CANCEL switch, push the ON/OFF
switch, or press the brake pedal.

NOISE
Diesel engines can create noises that may seem
concerning. The nature of a diesel engine is
compression ignition where compressed air and
fuel are mixed and ignited. Weather, barometric
pressure, altitude, and temperature will affect how
fuel is ignited in the engine. Engines will sound
different from day to day or previous model years.
Clicking, ticking, or light knocking is normal and will
change from day to day, as the engine breaks in, and can vary with changes in ambient
temperature. Clicking sound from under the hood
shortly after vehicle shutdown is normal as
actuators such as the EGR valve are cycled. Fuel
pump noise may increase during low speed/light
load conditions when ambient temperature is
above 100°F (38°C), and when fuel tank level is
below 10% which is a normal condition of the fuel
system and controls strategy. Diesel equipped
vehicles also have an exhaust after-treatment
system to reduce emissions utilizing a DPF (refer to
“Odor” in this section for further information) and a
Selective Reduction Catalyst (SCR). The SCR
reduces Nitrogen Oxides (NOx) using the Diesel
Exhaust Fluid (DEF) system. DEF is injected directly
into the SCR through a dosing module. This
process will create a clicking sound and at times, will make noise even with the vehicle shut off. This
is normal as the DEF dosing module is purging
DEF. If at any time the check engine light is on,
please visit an authorized dealer.

STOPPING THE ENGINE
Idle the engine a few minutes before routine
shutdown. After full load operation, idle the
engine three to five minutes before shutting it
down. This idle period will allow the lubricating
oil and coolant to carry excess heat away from
the combustion chamber, bearings, internal
components, and turbocharger. This is
especially important for turbocharged, charge
air-cooled engines. Refer to the following chart
for proper engine shutdown:
Driving Condition
Load Turbocharger Temperature Idle Time (min.) Before Engine
Shutdown
Stop and Go EmptyCoolLess than One
Stop and Go Medium -One
Highway Speeds MediumWarmTwo
City Traffic Maximum GCWR -Three
Highway Speeds Maximum GCWR -Four
Uphill Grade Maximum GCWR HotFive
5

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266STARTING AND OPERATING
If You Stall Or Begin To Lose Headway – If you
stall or begin to lose headway while climbing
a steep hill, allow your vehicle to come to a
stop and immediately apply the brake.
Restart the engine and shift into REVERSE.
Back slowly down the hill allowing the
compression braking of the engine and trans -
mission to help regulate your speed. If the
brakes are required to control vehicle speed,
apply them lightly and avoid locking or skid-
ding the tires.DRIVING THROUGH WATER
Extreme care should be taken crossing any type
of water. Water crossings should be avoided if
possible and only be attempted when
necessary, in a safe responsible manner. You
should only drive through areas which are
designated and approved. You should tread
lightly and avoid damage to the environment.
You should know your vehicle's abilities and be
able to recover it if something goes wrong. You
should never stop or shut a vehicle off when
crossing deep water unless you ingested water
into the engine air intake. If the engine stalls do
not attempt to restart it. Determine if it has
ingested water first. The key to any crossing is
low and slow. You want to use FIRST gear in
4WD LOW and proceed very slowly with a
constant slow speed (3-5 mph [5–8 km/h]
maximum) and light throttle. Keep the vehicle
moving; do not try to accelerate through the
crossing. After crossing any water higher than
the bottom of the axle differentials, you should
inspect all of the vehicle fluids for signs of water
ingestion.
Before You Cross Any Type Of Water – As you
approach any type of water you need to
determine if you can cross it safely and
responsibly. If necessary, get out and walk
through the water or probe it with a stick. You
need to be sure of its depth, approach angle,
current and bottom condition. Be careful of
murky or muddy waters, check for hidden
obstacles. Make sure you will not be
intruding on any wildlife and you can recover
the vehicle if necessary. The key to a safe
crossing is the water depth, current and
bottom conditions. On soft bottoms the
vehicle will sink in, effectively increasing the
water level on the vehicle. Be sure to
consider this when determining the depth
and the ability to safely cross.
WARNING!
If the engine stalls or you lose headway or
cannot make it to the top of a steep hill or
grade, never attempt to turn around. To do so
may result in tipping and rolling the vehicle,
which may result in severe injury. Always back
carefully straight down a hill in REVERSE.
Never back down a hill in NEUTRAL using only
the vehicle brakes. Never drive diagonally
across a hill, always drive straight up or down.
CAUTION!
Water ingestion into the axles, transmission,
transfer case, engine or vehicle interior can
occur if you drive too fast or through too deep
of water. Water can cause permanent
damage to engine, driveline or other vehicle
components and your brakes will be less
effective once wet and/or muddy.

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270STARTING AND OPERATING
AFTER DRIVING OFF-ROAD
Off-road operation puts more stress on your
vehicle than does most on-road driving. After
going off-road, it is always a good idea to check
for damage. That way you can get any problems
taken care of right away and have your vehicle
ready when you need it.
Completely inspect the underbody of your
vehicle. Check tires, body structure, steering,
suspension, and exhaust system for damage.
Inspect the radiator for mud and debris and
clean as required.
Check threaded fasteners for looseness,
particularly on the chassis, drivetrain compo -
nents, steering, and suspension. Retighten them, if required, and torque to the values
specified in the Service Manual.
Check for accumulations of plants or brush.
These things could be a fire hazard. They
might hide damage to fuel lines, brake hoses,
axle pinion seals, and propeller shafts.
After extended operation in mud, sand,
water, or similar dirty conditions, have the
radiator, fan, brake rotors, wheels, brake
linings, and axle yokes inspected and
cleaned as soon as possible.
If you experience unusual vibration after
driving in mud, slush or similar conditions,
check the wheels for impacted material.
Impacted material can cause a wheel imbal-
ance and freeing the wheels of it will correct
the situation.
LIMITED-SLIP DIFFERENTIAL
The limited-slip differential provides additional
traction on snow, ice, mud, sand and gravel,
particularly when there is a difference between
the traction characteristics of the surface under
the right and left rear wheels. During normal
driving and cornering, the limited-slip unit
performs similarly to a conventional differential.
On slippery surfaces, however, the differential
delivers more of the driving effort to the rear
wheel having the better traction.

The limited-slip differential is especially helpful
during slippery driving conditions. With both rear
wheels on a slippery surface, a slight application
of the accelerator will supply maximum traction.
When starting with only one rear wheel on an
excessively slippery surface, slight momentary
application of the parking brake may be
necessary to gain maximum traction.

WARNING!
Winch cables are under high tension when in
use and can become a projectile if they fail.
Never stand over or straddle the winch cable.
Never jerk or overload the winch cable. Never
stand in front of the vehicle while winching.
Failure to follow these instructions can result
in serious or fatal injury.
WARNING!
Abrasive material in any part of the brakes
may cause excessive wear or unpredictable
braking. You might not have full braking
power when you need it to prevent a collision.
If you have been operating your vehicle in
dirty conditions, get your brakes checked and
cleaned as necessary.
WARNING!
On vehicles equipped with a limited-slip
differential never run the engine with one rear
wheel off the ground since the vehicle may
drive through the rear wheel remaining on the
ground. You could lose control of the vehicle.

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344STARTING AND OPERATING
(Continued)
OFF-ROAD DRIVING TIPS
Care should be taken when attempting to climb
steep hills or driving diagonally across a hill or
slope. If natural obstacles force you to travel
diagonally up or down a hill, choose a mild angle
and keep as little side tilt as possible. Keep the
vehicle moving and make turns slowly and
cautiously.
If you must back down a hill, back straight down
using REVERSE gear. Never back down in
NEUTRAL or diagonally across the hill.
When driving over sand, mud, and other soft
terrain, shift to low gear and drive steadily.
Apply the accelerator slowly to avoid spinning
the wheels.
Do not reduce the tire pressures for this type of
driving.Driving through standing water limits your
vehicle’s braking capabilities, which
increases stopping distances. Therefore,
after driving through standing water, drive
slowly and lightly press on the brake pedal
several times to dry the brakes.
Failure to follow these warnings may result
in injuries that are serious or fatal to you,
your passengers, and others around you.
CAUTION!
Always check the depth of the standing
water before driving through it. Never drive
through standing water that is deeper than
the bottom of the tire rims mounted on the
vehicle.
Determine the condition of the road or the
path that is under water and if there are any
obstacles in the way before driving through
the standing water.
WARNING! (Continued)
Do not exceed 5 mph (8 km/h) when
driving through standing water. This will
minimize wave effects.
Driving through standing water may cause
damage to your vehicle’s drivetrain compo -
nents. Always inspect your vehicle’s fluids
(i.e., engine oil, transmission, axle, etc.) for
signs of contamination (i.e., fluid that is
milky or foamy in appearance) after driving
through standing water. Do not continue to
operate the vehicle if any fluid appears
contaminated, as this may result in further
damage. Such damage is not covered by
the New Vehicle Limited Warranty.
Getting water inside your vehicle’s engine
can cause it to lock up and stall out, and
cause serious internal damage to the
engine. Such damage is not covered by the
New Vehicle Limited Warranty.
CAUTION! (Continued)

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