ignition Ram 3500 2020 Service Manual

GETTING TO KNOW YOUR INSTRUMENT PANEL131
on, or turns on while driving, have the system
inspected at an authorized dealer as soon as
possible.
Brake Warning Light
This warning light monitors various
brake functions, including brake fluid
level and parking brake application. If
the brake light turns on it may
indicate that the parking brake is applied, that
the brake fluid level is low, or that there is a
problem with the Anti-Lock Brake System
reservoir.
If the light remains on when the parking brake
has been disengaged, and the fluid level is at
the full mark on the master cylinder reservoir, it
indicates a possible brake hydraulic system
malfunction or that a problem with the Brake
Booster has been detected by the Anti-Lock
Brake System (ABS) / Electronic Stability
Control (ESC) system. In this case, the light will
remain on until the condition has been
corrected. If the problem is related to the brake
booster, the ABS pump will run when applying
the brake, and a brake pedal pulsation may be
felt during each stop. The dual brake system provides a reserve
braking capacity in the event of a failure to a
portion of the hydraulic system. A leak in either
half of the dual brake system is indicated by the
Brake Warning Light, which will turn on when
the brake fluid level in the master cylinder has
dropped below a specified level.
The light will remain on until the cause is
corrected.
NOTE:
The light may flash momentarily during sharp
cornering maneuvers, which change fluid level
conditions. The vehicle should have service
performed, and the brake fluid level checked.
If brake failure is indicated, immediate repair is
necessary.
Vehicles equipped with the Anti-Lock Brake
System (ABS) are also equipped with Electronic
Brake Force Distribution (EBD). In the event of
an EBD failure, the Brake Warning Light will turn
on along with the ABS Light. Immediate repair to
the ABS system is required.
Operation of the Brake Warning Light can be
checked by turning the ignition switch from the
OFF position to the ON/RUN position. The light
should illuminate for approximately two
seconds. The light should then turn off unless
the parking brake is applied or a brake fault is
detected. If the light does not illuminate, have
the light inspected by an authorized dealer.
The light also will turn on when the parking
brake is applied with the ignition switch in the
ON/RUN position.
NOTE:
This light shows only that the parking brake is
applied. It does not show the degree of brake
application.
WARNING!
Driving a vehicle with the red brake light on is
dangerous. Part of the brake system may
have failed. It will take longer to stop the
vehicle. You could have a collision. Have the
vehicle checked immediately.
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132GETTING TO KNOW YOUR INSTRUMENT PANEL
Hood Open Warning Light
This warning light will illuminate when
the hood is ajar/open and not fully
closed.
NOTE:
If the vehicle is moving, there will also be a
single chime.
Vehicle Security Warning Light — If
Equipped
This light will flash at a fast rate for
approximately 15 seconds when the
vehicle security alarm is arming, and
then will flash slowly until the vehicle
is disarmed.
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 and idle the vehicle.
If the temperature reading does not return to
normal, turn the engine off immediately and call
for service.
Refer to “If Your Engine Overheats” in “In Case
Of Emergency” for further information.
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 Electronic
Throttle Control (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 (P) 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.

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GETTING TO KNOW YOUR INSTRUMENT PANEL133
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.
Trailer Brake Disconnected Warning Light
This warning light will illuminate when
the Trailer Brake has been
disconnected.
Refer to “Trailer Towing” in “Starting And
Operating” for further information.
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 (P) or NEUTRAL (N), 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 a local authorized dealer for
service.
For further information, refer to “Adaptive
Cruise Control (ACC)” in “Starting And
Operating.”
Air Suspension Fault Warning Light — If
Equipped
This light will illuminate when a fault is
detected with the air suspension
system.
Refer to “Air Suspension System — If Equipped”
in “Starting And Operating” for further
information.
Engine Check/Malfunction Indicator
Warning Light (MIL)
The Engine Check/Malfunction
Indicator Light (MIL) is a part of an
Onboard Diagnostic System called
OBD II that monitors engine and
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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134GETTING TO KNOW YOUR INSTRUMENT PANEL
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 Stability Control (ESC) Active
Warning Light — If Equipped
This warning light will indicate when
the Electronic Stability Control 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
Indicator Light” come on momentarily each
time the ignition is placed in the ON/RUN or
ACC/ON/RUN position.
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 PANEL135
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.
Electronic Stability Control (ESC) OFF
Warning Light — If Equipped
This warning light indicates the
Electronic Stability Control (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.
LaneSense Warning Light — If Equipped
The LaneSense system provides the
driver with visual and steering torque
warnings when the vehicle starts to
drift out of its lane unintentionally
without the use of a turn signal.
When the LaneSense system senses a lane
drift situation, the LaneSense indicator
changes from solid green to solid yellow.
When the LaneSense system senses the lane
has been approached and is in a lane depar -
ture situation, the LaneSense indicator
changes from solid white/green to flashing
yellow.
Refer to “LaneSense – If Equipped” in
“Starting And Operating” for further informa -
tion.
Service LaneSense Warning Light — If
Equipped
This warning light will illuminate when
the LaneSense system is not
operating and requires service.
Please see an authorized dealer.
Low Washer Fluid Warning Light
This warning light will illuminate when
the windshield washer fluid is low.
Refer to “Engine Compartment” in
“Servicing And Maintenance” for further
information.
Low Fuel Warning Light
When the fuel level reaches
approximately 3.2 gal (12 L) this light
will turn on, and remain on until fuel is
added.
A single warning chime will sound with Low Fuel
Warning.
Low Coolant Level Warning Light
This telltale will turn on to indicate the
vehicle coolant level is low.
Refer to “Fluids And Lubricants” in
“Technical Specifications” for further
information.
Loose Fuel Filler Cap Warning Light — If
Equipped
This warning light will illuminate when
the fuel filler cap is loose. Properly
close the filler cap to disengage the
light. If the light does not turn off,
please see an authorized dealer.
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GETTING TO KNOW YOUR INSTRUMENT PANEL137
Anti-Lock Brake System(ABS) Warning
Light

This warning light monitors the
Anti-Lock Brake System (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.
Refer to “Axle Locker System — Power Wagon
Models Only (If Equipped)” in “Starting And
Operating” for further information.
Service Forward Collision Warning (FCW)
Light — If Equipped
This warning light will illuminate to
indicate a fault in the Forward
Collision Warning System. Contact an
authorized dealer for service.
Refer to "Forward Collision Warning (FCW)" in
"Safety" for further information.
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.
Speed Control Fault Warning Light

This warning light will illuminate to
indicate the Speed Control System is
not functioning properly and service is
required. Contact an authorized dealer.

Sway Bar Fault Warning Light
This light will illuminate when there is
a fault in the sway bar disconnect
system.
Refer to “Stabilizer/Sway Bar System — Power
Wagon Only” in “Starting And Operating” for
further information.
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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140GETTING TO KNOW YOUR INSTRUMENT PANEL
Low Diesel Exhaust Fluid (DEF) Indicator
Light — If Equipped
The Low Diesel Exhaust Fluid (DEF)
Indicator will illuminate if the vehicle
is low on Diesel Exhaust Fluid (DEF).
Refer to “Starting And Operating” for
further information.
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.
Refer to “Starting The Engine” in “Starting And
Operating” for further information.
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.
Refer to the “Draining Fuel/Water Separator
Filter” section in “Dealer Service” in “Servicing
And Maintenance” for further information.
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.
Refer to “Adaptive Cruise Control
(ACC) — If Equipped” in “Starting And Operating”
for further information.
Adaptive Cruise Control (ACC) Set With No
Target Detected Indicator Light — If
Equipped
This light will turn on when the
Adaptive Cruise Control is SET and
there is no target vehicle detected.
Refer to "Adaptive Cruise Control (ACC) — If
Equipped" in "Starting And Operating" for
further information.
Automatic Diesel Exhaust Brake Indicator
Light — If Equipped
This indicator light will illuminate
when the Diesel Exhaust Brake has
been activated, and has switched to
Automatic mode.
Refer to “Diesel Exhaust Brake — Engine
Braking (If Equippes)” in “Starting And
Operating” for further information.
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.
Refer to “Exterior Lights” in “Getting To Know
Your Vehicle” for further information.
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

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GETTING TO KNOW YOUR INSTRUMENT PANEL143
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. If your OBD II system is not ready,
you should
see an authorized dealer or repair facility. If your
vehicle was recently serviced or had a battery
failure or replacement, you may need to do
nothing more than drive your vehicle as you
normally would in order for your OBD II system
to update. A recheck with the above test routine
may then indicate that the system is now ready.
Regardless of whether your vehicle's OBD II
system is ready or not, if the MIL is illuminated
during normal vehicle operation you should
have your vehicle serviced before going to the
I/M station. The I/M station can fail your vehicle
because the MIL is on with the engine running.
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SAFETY145
ABS is designed to function with the Original
Equipment Manufacturer (OEM) tires.
Modification may result in degraded ABS
performance.
Anti-Lock Brake Warning Light
The yellow “Anti-Lock Brake Warning Light” will
turn on when the ignition is placed in the ON/
RUN mode and may stay on for as long as four
seconds.
If the “Anti-Lock Brake Warning Light” remains
on or comes on while driving, it indicates that
the anti-lock portion of the brake system is not
functioning and that service is required.
However, the conventional brake system will
continue to operate normally if the “Anti-Lock
Brake Warning Light” is on.
If the “Anti-Lock Brake Warning Light” is on, the
brake system should be serviced as soon as
possible to restore the benefits of anti-lock
brakes. If the “Anti-Lock Brake Warning Light”
does not come on when the ignition is placed in
the ON/RUN mode, have the light repaired as
soon as possible.
ELECTRONIC BRAKE CONTROL (EBC)
S
YSTEM
Your vehicle is equipped with an advanced
Electronic Brake Control (EBC) system . This
system includes Electronic Brake Force
Distribution (EBD), Anti-Lock Brake System
(ABS), Brake Assist System (BAS), Hill Start
Assist (HSA), Traction Control System (TCS),
Electronic Stability Control (ESC), and Electronic
Roll Mitigation (ERM). These systems work
together to enhance both vehicle stability and
control in various driving conditions.
Your vehicle may also be equipped with Trailer
Sway Control (TSC) and Hill Descent Control
(HDC).
Brake Assist System (BAS)
The Brake Assist System (BAS) is designed to
optimize the vehicle’s braking capability during
emergency braking maneuvers. The system
detects an emergency braking situation by
sensing the rate and amount of brake
application and then applies optimum pressure
to the brakes. This can help reduce braking
distances. The BAS complements the Anti-Lock
Brake System (ABS). Applying the brakes very
quickly results in the best BAS assistance. To receive the benefit of the system, you must
apply continuous braking pressure during the
stopping sequence (do not “pump” the brakes).
Do not reduce brake pedal pressure unless
braking is no longer desired. Once the brake
pedal is released, the BAS is deactivated.
Brake System Warning Light
The red “Brake System Warning Light” will turn
on when the ignition is placed in the ON/RUN
mode and may stay on for as long as four
seconds.
WARNING!
The Brake Assist System (BAS) cannot
prevent the natural laws of physics from
acting on the vehicle, nor can it increase the
traction afforded by prevailing road
conditions. BAS cannot prevent collisions,
including those resulting from excessive
speed in turns, driving on very slippery
surfaces, or hydroplaning. The capabilities of
a BAS-equipped vehicle must never be
exploited in a reckless or dangerous manner,
which could jeopardize the user's safety or
the safety of others.
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146SAFETY
(Continued)
If the “Brake System Warning Light” remains on
or comes on while driving, it indicates that the
brake system is not functioning properly and
that immediate service is required. If the “Brake
System Warning Light” does not come on when
the ignition is placed in the ON/RUN mode,
have the light repaired as soon as possible.
Electronic Brake Force Distribution (EBD)
This function manages the distribution of the
braking torque between the front and rear axles
by limiting braking pressure to the rear axle.
This is done to prevent overslip of the rear
wheels to avoid vehicle instability, and to
prevent the rear axle from entering Anti-Lock
Brake System (ABS) before the front axle.
Electronic Stability Control (ESC)
This system enhances directional control and
stability of the vehicle under various driving
conditions. Electronic Stability Control (ESC)
corrects for oversteering or understeering of the
vehicle by applying the brake of the appropriate
wheel(s) to assist in counteracting the oversteer
or understeer condition. Engine power may also
be reduced to help the vehicle maintain the
desired path.ESC uses sensors in the vehicle to determine
the vehicle path intended by the driver and
compares it to the actual path of the vehicle.
When the actual path does not match the
intended path, ESC applies the brake of the
appropriate wheel to assist in counteracting the
oversteer or understeer condition.

Oversteer — when the vehicle is turning
more than appropriate for the steering
wheel position.
Understeer — when the vehicle is turning
less than appropriate for the steering wheel
position.

The “ESC Activation/Malfunction Indicator
Light” located in the instrument cluster will start
to flash as soon as the ESC system becomes
active. The “ESC Activation/Malfunction
Indicator Light” also flashes when the TCS is
active. If the “ESC Activation/Malfunction
Indicator Light” begins to flash during
acceleration, ease up on the accelerator and
apply as little throttle as possible. Be sure to
adapt your speed and driving to the prevailing
road conditions.
WARNING!
Electronic Stability Control (ESC) cannot
prevent the natural laws of physics from
acting on the vehicle, nor can it increase
the traction afforded by prevailing road
conditions. ESC cannot prevent accidents,
including those resulting from excessive
speed in turns, driving on very slippery
surfaces, or hydroplaning. ESC also cannot
prevent accidents resulting from loss of
vehicle control due to inappropriate driver
input for the conditions. Only a safe, atten -
tive, and skillful driver can prevent acci -
dents. The capabilities of an ESC equipped
vehicle must never be exploited in a reck -
less or dangerous manner which could
jeopardize the user’s safety or the safety of
others.

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