warning RAM 1500 2021 Repair Manual

128GETTING TO KNOW YOUR INSTRUMENT PANEL
Engine Coolant Temperature Warning
Light
This warning light warns of an
overheated engine condition. If the
engine coolant temperature is too
high, this indicator will illuminate and
a single chime will sound. If the temperature
reaches the upper limit, a continuous chime will
sound for four minutes or until the engine is
able to cool, whichever comes first.
If the light turns on while driving, safely pull over
and stop the vehicle. If the Air Conditioning (A/
C) system is on, turn it off. Also, shift the
transmission into NEUTRAL (N) and idle the
vehicle. If the temperature reading does not
return to normal, turn the engine off
immediately and call for service Ú page 389.
Battery Charge Warning Light
This warning light will illuminate when
the battery is not charging properly. If
it stays on while the engine is running,
there may be a malfunction with the
charging system. Contact an authorized dealer
as soon as possible.
This indicates a possible problem with the
electrical system or a related component.
Oil Pressure Warning Light
This warning light will illuminate to
indicate low engine oil pressure. If the
light turns on while driving, stop the
vehicle, shut off the engine as soon as
possible, and contact an authorized dealer. A
chime will sound when this light turns on.
Do not operate the vehicle until the cause is
corrected. This light does not indicate how
much oil is in the engine. The engine oil level
must be checked under the hood.
Oil Temperature Warning Light
This warning light will illuminate to
indicate the engine oil temperature is
high. If the light turns on while driving,
stop the vehicle and shut off the
engine as soon as possible. Wait for oil
temperature to return to normal levels.
Electronic Throttle Control (ETC) Warning
Light
This warning light will illuminate to
indicate a problem with the ETC
system. If a problem is detected while
the vehicle is running, the light will
either stay on or flash depending on the nature
of the problem. Cycle the ignition when the vehicle is safely and completely stopped and
the transmission is placed in the PARK position.
The light should turn off. If the light remains on
with the vehicle running, your vehicle will
usually be drivable; however, see an authorized
dealer for service as soon as possible.
NOTE:
This light may turn on if the accelerator and
brake pedals are pressed at the same time.
If the light continues to flash when the vehicle is
running, immediate service is required and you
may experience reduced performance, an
elevated/rough idle, or engine stall and your
vehicle may require towing. The light will come
on when the ignition is placed in the ON/RUN or
ACC/ON/RUN position and remain on briefly as
a bulb check. If the light does not come on
during starting, have the system checked by an
authorized dealer.

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GETTING TO KNOW YOUR INSTRUMENT PANEL129
Electric Power Steering (EPS) Fault
Warning Light
This warning light will turn on when
there's a fault with the EPS system
Úpage 174.
Tailgate Open Warning Light
This warning light will illuminate when
the tailgate is open.
NOTE:
If the vehicle is moving, there will also be a
single chime.
Trailer Brake Disconnected Warning Light
This warning light will illuminate when
the Trailer Brake has been
disconnected.
Transmission Temperature Warning Light
— If Equipped
This warning light will illuminate to
warn of a high transmission fluid
temperature. This may occur with
strenuous usage such as trailer
towing. If this light turns on, stop the vehicle and
run the engine at idle or slightly faster, with the
transmission in PARK or NEUTRAL, until the
light turns off. Once the light turns off, you may
continue to drive normally.
Door Open Warning Light
This indicator will illuminate when a
door is ajar/open and not fully closed.
NOTE:
If the vehicle is moving there will also be a single
chime.
YELLOW WARNING LIGHTS
Adaptive Cruise Control (ACC) Fault
Warning Light — If Equipped
This warning light will illuminate to
indicate a fault in the ACC system.
Contact an authorized dealer for
service Ú page 179.
Air Suspension Fault Warning Light — If
Equipped
This light will illuminate when a fault is
detected with the air suspension
system.
WARNING!
Continued operation with reduced assist
could pose a safety risk to yourself and
others. Service should be obtained as soon
as possible.
WARNING!
If you continue operating the vehicle when
the Transmission Temperature Warning Light
is illuminated you could cause the fluid to boil
over, come in contact with hot engine or
exhaust components and cause a fire.
CAUTION!
Continuous driving with the Transmission
Temperature Warning Light illuminated will
eventually cause severe transmission
damage or transmission failure.
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130GETTING TO KNOW YOUR INSTRUMENT PANEL
Engine Check/Malfunction Indicator
Warning Light (MIL)
The MIL is a part of an Onboard
Diagnostic System called OBD II that
monitors engine and automatic
transmission control systems. This
warning light will illuminate when the ignition is
in the ON/RUN position before engine start. If
the bulb does not come on when turning the
ignition switch from OFF to ON/RUN, have the
condition checked promptly.
Certain conditions, such as a loose or missing
gas cap, poor quality fuel, etc., may illuminate
the light after engine start. The vehicle should
be serviced if the light stays on through several
typical driving styles. In most situations, the
vehicle will drive normally and will not require
towing.
When the engine is running, the MIL may flash
to alert serious conditions that could lead to
immediate loss of power or severe catalytic
converter damage. The vehicle should be
serviced by an authorized dealer as soon as
possible if this occurs.
Electronic Park Brake Warning Light
This warning light will illuminate to
indicate the Electronic Park Brake is
not functioning properly and service is
required. Contact an authorized
dealer.
Electronic Stability Control (ESC) Active
Warning Light — If Equipped
This warning light will indicate when
the ESC system is Active. The ESC
Indicator Light in the instrument
cluster will come on when the ignition
is placed in the ON/RUN or ACC/ON/RUN
position, and when ESC is activated. It should go
out with the engine running. If the ESC Indicator
Light comes on continuously with the engine
running, a malfunction has been detected in the
ESC system. If this warning light remains on after
several ignition cycles, and the vehicle has been
driven several miles (kilometers) at speeds
greater than 30 mph (48 km/h), see an
authorized dealer as soon as possible to have
the problem diagnosed and corrected.
The ESC OFF Indicator Light and the ESC Indi -
cator Light come on momentarily each time
the ignition is placed in the ON/RUN or ACC/
ON/RUN position.
The ESC system will make buzzing or clicking
sounds when it is active. This is normal; the
sounds will stop when ESC becomes inactive.
This light will come on when the vehicle is in
an ESC event.
WARNING!
A malfunctioning catalytic converter, as
referenced above, can reach higher
temperatures than in normal operating
conditions. This can cause a fire if you drive
slowly or park over flammable substances
such as dry plants, wood, cardboard, etc. This
could result in death or serious injury to the
driver, occupants or others.
CAUTION!
Prolonged driving with the Malfunction
Indicator Light (MIL) on could cause damage
to the vehicle control system. It also could
affect fuel economy and driveability. If the
MIL is flashing, severe catalytic converter
damage and power loss will soon occur.
Immediate service is required.

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GETTING TO KNOW YOUR INSTRUMENT PANEL131
Electronic Stability Control (ESC) OFF
Warning Light — If Equipped
This warning light indicates the ESC is
off.
Each time the ignition is turned to ON/RUN or
ACC/ON/RUN, the ESC system will be on, even
if it was turned off previously.
Service LaneSense Warning Light — If
Equipped
This warning light will illuminate when
the LaneSense system is not
operating and requires service.
Please contact an authorized dealer.
Low Washer Fluid Warning Light — If
Equipped
This warning light will illuminate when
the windshield washer fluid is low.
Low Fuel Warning Light
When the fuel level is less than a ¼
tank, and the Distance to Empty is
less than 50 miles, this light will turn
on and remain on until fuel is added. A single warning chime will sound with Low Fuel
Warning.
Tire Pressure Monitoring System (TPMS)
Warning Light
The warning light switches on and a
message is displayed to indicate that
the tire pressure is lower than the
recommended value and/or that slow
pressure loss is occurring. In these cases,
optimal tire duration and fuel consumption may
not be guaranteed.
Should one or more tires be in the condition
mentioned above, the display will show the
indications corresponding to each tire.
Each tire, including the spare (if provided),
should be checked monthly when cold and
inflated to the inflation pressure recommended by the vehicle manufacturer on the vehicle
placard or tire inflation pressure label. If your
vehicle has tires of a different size than the size
indicated on the vehicle placard or tire inflation
pressure label, you should determine the
proper tire inflation pressure for those tires.
As an added safety feature, your vehicle has
been equipped with a Tire Pressure Monitoring
System (TPMS) that illuminates a low tire
pressure telltale when one or more of your tires
is significantly under-inflated. Accordingly, when
the low tire pressure telltale illuminates, you
should stop and check your tires as soon as
possible, and inflate them to the proper
pressure. Driving on a significantly
under-inflated tire causes the tire to overheat
and can lead to tire failure. Under-inflation also
reduces fuel efficiency and tire tread life, and
may affect the vehicle’s handling and stopping
ability.
Please note that the TPMS is not a substitute for
proper tire maintenance, and it is the driver’s
responsibility to maintain correct tire pressure,
even if under-inflation has not reached the level
to trigger illumination of the TPMS low tire
pressure telltale.
CAUTION!
Do not continue driving with one or more flat
tires as handling may be compromised. Stop
the vehicle, avoiding sharp braking and
steering. If a tire puncture occurs, repair
immediately using the dedicated tire repair
kit and contact an authorized dealer as soon
as possible.
3

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132GETTING TO KNOW YOUR INSTRUMENT PANEL
Your vehicle has also been equipped with a
TPMS malfunction indicator to indicate when
the system is not operating properly. The TPMS
malfunction indicator is combined with the low
tire pressure telltale. When the system detects
a malfunction, the telltale will flash for
approximately one minute and then remain
continuously illuminated. This sequence will
continue upon subsequent vehicle start-ups as
long as the malfunction exists. When the
malfunction indicator is illuminated, the system
may not be able to detect or signal low tire
pressure as intended. TPMS malfunctions may
occur for a variety of reasons, including the
installation of replacement or alternate tires or
wheels on the vehicle that prevent the TPMS
from functioning properly. Always check the
TPMS malfunction telltale after replacing one or
more tires or wheels on your vehicle to ensure
that the replacement or alternate tires and
wheels allow the TPMS to continue to function
properly.
Anti-Lock Brake System (ABS) Warning
Light
This warning light monitors the ABS.
The light will turn on when the ignition
is placed in the ON/RUN or ACC/ON/
RUN position and may stay on for as
long as four seconds.If the ABS light remains on or turns on while
driving, then the Anti-Lock portion of the brake
system is not functioning and service is
required as soon as possible. However, the
conventional brake system will continue to
operate normally, assuming the Brake Warning
Light is not also on.
If the ABS light does not turn on when the
ignition is placed in the ON/RUN or ACC/ON/
RUN position, have the brake system inspected
by an authorized dealer.
Rear Axle Locker Fault Indicator Light — If
Equipped
This warning light will illuminate to
indicate when a rear axle locker fault
has been detected.
Service Forward Collision Warning (FCW)
Light — If Equipped
This warning light will illuminate to
indicate a fault in the FCW System.
Contact an authorized dealer for
service Ú
page 324.
CAUTION!
The TPMS has been optimized for the original
equipment tires and wheels. TPMS pressures
and warning have been established for the
tire size equipped on your vehicle.
Undesirable system operation or sensor
damage may result when using replacement
equipment that is not of the same size, type,
and/or style. Aftermarket wheels can cause
sensor damage. Using aftermarket tire
sealants may cause the Tire Pressure
Monitoring System (TPMS) sensor to become
inoperable. After using an aftermarket tire
sealant it is recommended that you take your
vehicle to an authorized dealer to have your
sensor function checked.

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GETTING TO KNOW YOUR INSTRUMENT PANEL133
Service Stop/Start System Warning Light —
If Equipped
This warning light will illuminate when
the Stop/Start system is not
functioning properly and service is
required. Contact an authorized
dealer for service.
Service 4WD Warning Light — If Equipped
This warning light will illuminate to
signal a fault with the 4WD system. If
the light stays on or comes on during
driving, it means that the 4WD system
is not functioning properly and that service is
required. We recommend you drive to the
nearest service center and have the vehicle
serviced immediately.
Cruise Control Fault Warning Light
This warning light will illuminate to
indicate the Cruise Control System is
not functioning properly and service is
required. Contact an authorized
dealer.
YELLOW INDICATOR LIGHTS
Forward Collision Warning Off Indicator
Light — If Equipped
This indicator light illuminates to
indicate that Forward Collision
Warning is off.
Air Suspension Payload Protection
Indicator Light — If Equipped
This indicator light will illuminate to
indicate that the maximum payload
may have been exceeded or load
leveling cannot be achieved at its
current ride height. Protection Mode will
automatically be selected to “protect” the air
suspension system, air suspension adjustment
is limited due to payload.
Trailer Merge Assist Indicator Light — If
Equipped
This indicator light will illuminate to
indicate when Trailer Merge Assist
has been activated Ú page 318.
TOW/HAUL Indicator Light
This indicator light will illuminate
when TOW/HAUL mode is selected.
Cargo Light — If Equipped
This indicator light will illuminate
when the cargo light is activated by
pushing the cargo light button on the
headlight switch.
Air Suspension Off-Road 1 Indicator Light
— If Equipped
This light will illuminate when the air
suspension system is set to the
Off-Road 1 setting Úpage 165.
Air Suspension Off-Road 2 Indicator Light
— If Equipped
This light will illuminate when the air
suspension system is set to the
Off-Road 2 setting Úpage 165.
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GETTING TO KNOW YOUR INSTRUMENT PANEL135
Wait To Start Light — If Equipped
This indicator light will illuminate for
approximately two seconds when the
ignition is turned to the RUN position.
Its duration may be longer based on
colder operating conditions. Vehicle will not
initiate start until telltale is no longer displayed
Ú page 146.
NOTE:
The “Wait To Start” telltale may not illuminate if
the intake manifold temperature is warm
enough.
Water In Fuel Indicator Light — If Equipped
The “Water In Fuel Indicator Light” will
illuminate when there is water
detected in the fuel filter. If this light
remains on, DO NOT start the vehicle
before you drain the water from the fuel filter to
prevent engine damage, and please see an
authorized dealer.GREEN INDICATOR LIGHTS
Adaptive Cruise Control (ACC) Set With
Target Light — If Equipped
This will display when the ACC is set
and a target vehicle is detected
Ú page 179.
Adaptive Cruise Control (ACC) Set With No
Target Detected Indicator Light — If
Equipped
This light will turn on when the ACC is
SET and there is no target vehicle
detected Ú page 179.
ECO Mode Indicator Light
This light will turn on when ECO Mode
is active.
Park/Headlight On Indicator Light
This indicator light will illuminate
when the park lights or headlights are
turned on.
LaneSense Indicator Light — If Equipped
The LaneSense indicator light
illuminates solid green when both
lane markings have been detected
and the system is “armed” and ready
to provide visual and torque warnings if an
unintentional lane departure occurs
Ú page 199.
CAUTION!
The presence of water in the fuel system
circuit may cause severe damage to the
injection system and irregular engine
operation. If the indicator light is illuminated,
contact an authorized dealer as soon as
possible to bleed the system. If the above
indications come on immediately after
refuelling, water has probably been poured
into the tank: switch the engine off
immediately and contact an authorized
dealer.
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GETTING TO KNOW YOUR INSTRUMENT PANEL137
Hill Descent Control (HDC) Indicator Light
— If Equipped
This indicator shows when the HDC
feature is turned on. The lamp will be
on solid when HDC is armed. HDC can
only be armed when the transfer case
is in the “4WD LOW” position and the vehicle
speed is less then 20 mph (32 km/h). If these
conditions are not met while attempting to use
the HDC feature, the HDC indicator light will
flash on/off.
LaneSense Indicator Light — If Equipped
When the LaneSense system is ON,
but not armed, the LaneSense
indicator light illuminates solid white.
This occurs when only left, right, or
neither lane line has been detected. If a single
lane line is detected, the system is ready to
provide only visual warnings if an unintentional
lane departure occurs on the detected lane line
Ú page 199.
BLUE INDICATOR LIGHTS
High Beam Indicator Light
This indicator light will illuminate to
indicate that the high beam
headlights are on. With the low beams
activated, push the multifunction
lever forward (toward the front of the vehicle) to
turn on the high beams. Pull the multifunction
lever rearward (toward the rear of the vehicle) to
turn off the high beams. If the high beams are
off, pull the lever toward you for a temporary
high beam on, “flash to pass” scenario.
ONBOARD DIAGNOSTIC SYSTEM — OBD II
Your vehicle is equipped with a sophisticated
Onboard Diagnostic system called OBD II. This
system monitors the performance of the
emissions, engine, and transmission control
systems. When these systems are operating
properly, your vehicle will provide excellent
performance and fuel economy, as well as
engine emissions well within current
government regulations. If any of these systems require service, the OBD
II system will turn on the Malfunction Indicator
Light (MIL). It will also store diagnostic codes
and other information to assist your service
technician in making repairs. Although your
vehicle will usually be drivable and not need
towing, see an authorized dealer for service as
soon as possible.
CAUTION!
Prolonged driving with the MIL on could
cause further damage to the emission
control system. It could also affect fuel
economy and driveability. The vehicle must
be serviced before any emissions tests can
be performed.
If the MIL is flashing while the vehicle is
running, severe catalytic converter damage
and power loss will soon occur. Immediate
service is required.
3

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138GETTING TO KNOW YOUR INSTRUMENT PANEL
ONBOARD DIAGNOSTIC SYSTEM
(OBD II) C
YBERSECURITY
Your vehicle is required to have OBD II and a
connection port to allow access to information
related to the performance of your emissions
controls. Authorized service technicians may
need to access this information to assist with
the diagnosis and service of your vehicle and
emissions system Ú page 236.
EMISSIONS INSPECTION AND
MAINTENANCE PROGRAMS
In some localities, it may be a legal requirement
to pass an inspection of your vehicle's
emissions control system. Failure to pass could
prevent vehicle registration.
For states that require an Inspection
and Maintenance (I/M), this check
verifies the Malfunction Indicator
Light (MIL) is functioning and is not on
when the engine is running, and that the OBD II
system is ready for testing.
Normally, the OBD II system will be ready. The
OBD II system may not be ready if your vehicle
was recently serviced, recently had a depleted
battery or a battery replacement. If the OBD II
system should be determined not ready for the
I/M test, your vehicle may fail the test.
Your vehicle has a simple ignition actuated test,
which you can use prior to going to the test
station. To check if your vehicle's OBD II system
is ready, you must do the following:
1. Cycle the ignition switch to the ON position,
but do not crank or start the engine.

NOTE:
If you crank or start the engine, you will have to
start this test over.
2. As soon as you cycle the ignition switch to the ON position, you will see the
Malfunction Indicator Light (MIL) symbol
come on as part of a normal bulb check.
3. Approximately 15 seconds later, one of two things will happen:
The MIL will flash for about 10 seconds
and then return to being fully illuminated
until you turn OFF the ignition or start the
engine. This means that your vehicle's
OBD II system is not ready and you
should not proceed to the I/M station.
The MIL will not flash at all and will
remain fully illuminated until you place
the ignition in the off position or start the
engine. This means that your vehicle's
OBD II system is ready and you can
proceed to the I/M station.
WARNING!
ONLY an authorized service technician
should connect equipment to the OBD II
connection port in order to read the VIN,
diagnose, or service your vehicle.
If unauthorized equipment is connected to
the OBD II connection port, such as a
driver-behavior tracking device, it may:
Be possible that vehicle systems,
including safety related systems, could
be impaired or a loss of vehicle control
could occur that may result in an acci -
dent involving serious injury or death.
Access, or allow others to access, infor -
mation stored in your vehicle systems,
including personal information.

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140 (Continued)
(Continued)
STARTING AND OPERATING
STARTING THE ENGINE
GASOLINE ENGINE
Before starting your vehicle, adjust your seat,
adjust both inside and outside mirrors, and
fasten your seat belt.
The starter should not be operated for more
than 10-second intervals. Waiting a few
seconds between such intervals will protect the
starter from overheating. DIESEL ENGINE
Before starting your vehicle, adjust your seat,
both inside and outside mirrors, and fasten your
seat belts.
The starter is allowed to crank for up to
25-second intervals. Waiting a few minutes
between such intervals will protect the starter
from overheating.
WARNING!
When leaving the vehicle, always make
sure the keyless ignition node is in the OFF
mode, remove the key fob from the vehicle
and lock the vehicle.
Never leave children alone in a vehicle, or
with access to an unlocked vehicle.
Allowing children to be in a vehicle unat-
tended is dangerous for a number of
reasons. A child or others could be seriously
or fatally injured. Children should be
warned not to touch the parking brake,
brake pedal or the gear selector.
Do not leave the key fob in or near the
vehicle, or in a location accessible to chil-
dren, and do not leave the ignition of a
vehicle equipped with Keyless Enter-N-Go
in the ACC or ON/RUN mode. A child could
operate power windows, other controls, or
move the vehicle.
Do not leave children or animals inside
parked vehicles in hot weather. Interior
heat build-up may cause serious injury or
death.
WARNING! (Continued)WARNING!
Before exiting a vehicle, always come to a
complete stop, then shift the automatic
transmission into PARK and apply the
parking brake.
Always make sure the ENGINE START/STOP
button is in the OFF mode, key fob is
removed from the vehicle and vehicle is
locked.
Never leave children alone in a vehicle, or
with access to an unlocked vehicle. Leaving
children in a vehicle unattended is
dangerous for a number of reasons. A child
or others could be seriously or fatally
injured. Children should be warned not to
touch the parking brake, brake pedal or the
gear selector.

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