2020 Ram 2500 warning light

142GETTING TO KNOW YOUR INSTRUMENT PANEL
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.
Onboard Diagnostic System (OBD II)
Cybersecurity
Your vehicle is required to have an Onboard
Diagnostic system (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 diag-
nosis and service of your vehicle and emissions
system. For further information, refer to “Cybersecurity”
in “Multimedia”.
EMISSIONS INSPECTION AND
MAINTENANCE PROGRAMS
In some localities, it may be a legal requirement
to pass an inspection of your vehicle's emis
-sions 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.
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.
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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144 (Continued)
SAFETY
SAFETY FEATURES
Anti-Lock Brake System (ABS)
The Anti-Lock Brake System (ABS) provides
increased vehicle stability and brake perfor-
mance under most braking conditions. The
system automatically prevents wheel lock, and
enhances vehicle control during braking.
The ABS performs a self-check cycle to ensure
that the ABS is working properly each time the
vehicle is started and driven. During this
self-check, you may hear a slight clicking sound
as well as some related motor noises.
ABS is activated during braking when the
system detects one or more wheels begin to
lock. Road conditions such as ice, snow, gravel,
bumps, railroad tracks, loose debris, or panic
stops may increase the likelihood of ABS activa-
tion(s). You also may experience the following when
ABS activates:
The ABS motor noise (it may continue to run
for a short time after the stop)
The clicking sound of solenoid valves
Brake pedal pulsations
A slight drop of the brake pedal at the end of
the stop
These are all normal characteristics of ABS.
WARNING!
The ABS contains sophisticated electronic
equipment that may be susceptible to inter -
ference caused by improperly installed or
high output radio transmitting equipment.
This interference can cause possible loss of
anti-lock braking capability. Installation of
such equipment should be performed by
qualified professionals.
Pumping of the Anti-Lock Brakes will
diminish their effectiveness and may lead
to a collision. Pumping makes the stopping
distance longer. Just press firmly on your
brake pedal when you need to slow down or
stop.
The ABS cannot prevent the natural laws of
physics from acting on the vehicle, nor can
it increase braking or steering efficiency
beyond that afforded by the condition of the
vehicle brakes and tires or the traction
afforded.
The ABS cannot prevent collisions,
including those resulting from excessive
speed in turns, following another vehicle
too closely, or hydroplaning.
The capabilities of an ABS equipped vehicle
must never be exploited in a reckless or
dangerous manner that could jeopardize
the user’s safety or the safety of others.
WARNING! (Continued)

20_DJD2_OM_EN_USC_t.book Page 144

SAFETY145
ABS is designed to function with the Original
Equipment Manufacturer (OEM) tires. Modifica -
tion 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) System
Your vehicle is equipped with an advanced Elec -
tronic 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 Miti
-
gation (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 applica -
tion 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 stop-
ping 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.
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.
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.
4

20_DJD2_OM_EN_USC_t.book Page 145

146SAFETY
(Continued)
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 posi-
tion.
Understeer — when the vehicle is turning less
than appropriate for the steering wheel posi -
tion.
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 Indi -
cator 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.

20_DJD2_OM_EN_USC_t.book Page 146

SAFETY147
ESC Operating Modes
NOTE:
Depending upon model and mode of operation,
the ESC system may have multiple operating
modes. ESC On
This is the normal operating mode for the ESC.
Whenever the vehicle is started, the ESC system
will be in this mode. This mode should be used
for most driving conditions. Alternate ESC
modes should only be used for specific reasons
as noted in the following paragraphs.
Partial Off
The “Partial Off” mode is intended for times
when a more spirited driving experience is
desired. This mode may modify TCS and ESC
thresholds for activation, which allows for more
wheel spin than normally allowed. This mode
may be useful if the vehicle becomes stuck.
To enter the “Partial Off” mode, momentarily
push the “ESC OFF” switch and the “ESC OFF
Indicator Light” will illuminate. To turn the ESC
on again, momentarily push the “ESC OFF”
switch and the “ESC OFF Indicator Light” will
turn off.
NOTE:
For vehicles with multiple partial ESC modes, a
momentary button push will toggle the ESC
mode. Multiple momentary button pushes may
be required to return to ESC On.
Full Off — If Equipped
This mode is intended for off-highway or
off-road use only and should not be used on any
public roadways. In this mode, TCS and ESC
features are turned off. To enter the “Full Off”
mode, push and hold the “ESC OFF” switch for
five seconds while the vehicle is stopped with
the engine running. After five seconds, a chime
will sound, the “ESC OFF Indicator Light” will illu
-
minate, and the “ESC OFF” message will display
in the instrument cluster. To turn ESC on again,
momentarily push the “ESC OFF” switch.
Vehicle modifications, or failure to properly
maintain your vehicle, may change the
handling characteristics of your vehicle,
and may negatively affect the performance
of the ESC system. Changes to the steering
system, suspension, braking system, tire
type and size or wheel size may adversely
affect ESC performance. Improperly
inflated and unevenly worn tires may also
degrade ESC performance. Any vehicle
modification or poor vehicle maintenance
that reduces the effectiveness of the ESC
system can increase the risk of loss of
vehicle control, vehicle rollover, personal
injury and death.
WARNING! (Continued)WARNING!
When in “Partial Off” mode, the TCS func -
tionality of ESC, (except for the limited slip
feature described in the TCS section), has
been disabled and the “ESC Off Indicator
Light” will be illuminated. When in “Partial
Off” mode, the engine power reduction
feature of TCS is disabled, and the
enhanced vehicle stability offered by the
ESC system is reduced.
Trailer Sway Control (TSC) is disabled when
the ESC system is in the “Partial Off” mode.
4

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148SAFETY
(Continued)
NOTE:
System may switch from ESC “Full Off” to
“Partial Off” mode when vehicle exceeds a
predetermined speed. When the vehicle speed
slows below the predetermined speed the
system will return to ESC “Full Off”.
ESC modes may also be affected by drive
modes (if equipped).
ESC Activation/Malfunction Indicator Light
And ESC OFF Indicator Light
The “ESC Activation/Malfunction Indi -
cator Light” in the instrument cluster
will come on when the ignition is
turned to the ON mode. It should go
out with the engine running. If the “ESC Activa -
tion/Malfunction Indicator Light” comes on
continuously with the engine running, a
malfunction has been detected in the ESC
system. If this 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 Activation/Malfunction Indicator
Light” (located in the instrument cluster) starts
to flash as soon as the tires lose traction and
the ESC system becomes active. The “ESC Acti
-
vation/Malfunction Indicator Light” also flashes
when 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.
NOTE:
The “ESC Activation/Malfunction Indicator
Light” and the “ESC OFF Indicator Light”
come on momentarily each time the ignition
is placed in the ON position.
Each time the ignition is placed in the ON
position, the ESC system will be on even if it
was turned off previously.
The ESC system will make buzzing or clicking
sounds when it is active. This is normal; the
sounds will stop when ESC becomes inactive
following the maneuver that caused the ESC
activation.
WARNING!
In the ESC “Full Off” mode, the engine
torque reduction and stability features are
disabled. Therefore, enhanced vehicle
stability offered by the ESC system is
unavailable. In an emergency evasive
maneuver, the ESC system will not engage
to assist in maintaining stability. ESC “Full
Off” mode is intended for off-highway or
off-road use only.
The 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 all
accidents, including those resulting from
excessive speed in turns, driving on very
slippery surfaces, or hydroplaning. ESC also
cannot prevent collisions.
WARNING! (Continued)

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SAFETY149
The “ESC OFF Indicator Light” indi -
cates the customer has elected to
have the Electronic Stability Control
(ESC) in a reduced mode.
Electronic Roll Mitigation (ERM)
This system anticipates the potential for wheel
lift by monitoring the driver’s steering wheel
input and the speed of the vehicle. When Elec -
tronic Roll Mitigation (ERM) determines that the
rate of change of the steering wheel angle and
vehicle’s speed are sufficient to potentially
cause wheel lift, it then applies the appropriate
brake and may also reduce engine power to
lessen the chance that wheel lift will occur. ERM
can only reduce the chance of wheel lift occur -
ring during severe or evasive driving maneu -
vers; it cannot prevent wheel lift due to other
factors, such as road conditions, leaving the
roadway, or striking objects or other vehicles.
NOTE:
ERM is disabled anytime the ESC is in “Full Off”
mode (if equipped). Refer to “Electronic Stability
Control (ESC)” in this section for a complete
explanation of the available ESC modes.
Hill Descent Control (HDC) — If Equipped
Hill Descent Control (HDC) is intended for low
speed off road driving while in 4L Range. HDC
maintains vehicle speed while descending hills
during various driving situations. HDC controls
vehicle speed by actively controlling the brakes. HDC Has Three States:

1. Off (feature is not enabled and will not acti
-
vate)

2. Enabled (feature is enabled and ready but activation conditions are not met, or driver
is actively overriding with brake or throttle
application)
3. Active (feature is enabled and actively controlling vehicle speed)
Enabling HDC
HDC is enabled by pushing the HDC switch, but
the following conditions must also be met to
enable HDC:Driveline is in 4L Range
Vehicle speed is below 5 mph (8 km/h)
Parking brake is released
Driver door is closed
WARNING!
Many factors, such as vehicle loading, road
conditions and driving conditions, influence
the chance that wheel lift or rollover may
occur. ERM cannot prevent all wheel lift or roll
overs, especially those that involve leaving
the roadway or striking objects or other
vehicles. The capabilities of an
ERM-equipped vehicle must never be
exploited in a reckless or dangerous manner
which could jeopardize the user's safety or
the safety of others.
4

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SAFETY151
The cluster icon and switch lamp will flash for
several seconds then extinguish when HDC
disables due to excess speed.
The cluster icon and switch lamp will flash
when HDC deactivates due to overheated
brakes. The flashing will stop and HDC will
activate again once the brakes have cooled
sufficiently.
Hill Start Assist (HSA)
The Hill Start Assist (HSA) system is designed to
mitigate roll back from a complete stop while on
an incline. If the driver releases the brake while
stopped on an incline, HSA will continue to hold
the brake pressure for a short period. If the
driver does not apply the throttle before this
time expires, the system will release brake pres -
sure and the vehicle will roll down the hill as
normal. The following conditions must be met in order
for HSA to activate:
The feature must be enabled.
The vehicle must be stopped.
The park brake must be off.
The driver door must be closed.
The vehicle must be on a sufficient grade.
The gear selection must match vehicle uphill
direction (i.e., vehicle facing uphill is in
forward gear; vehicle backing uphill is in
REVERSE (R) gear).
HSA will work in REVERSE gear and all
forward gears. The system will not activate if
the transmission is in PARK or NEUTRAL (N).
For vehicles equipped with a manual trans
-
mission, if the clutch is pressed, HSA will
remain active.
WARNING!
HDC is only intended to assist the driver in
controlling vehicle speed when descending
hills. The driver must remain attentive to the
driving conditions and is responsible for
maintaining a safe vehicle speed.
WARNING!
There may be situations where the Hill Start
Assist (HSA) will not activate and slight rolling
may occur, such as on minor hills or with a
loaded vehicle, or while pulling a trailer. HSA
is not a substitute for active driving
involvement. It is always the driver’s
responsibility to be attentive to distance to
other vehicles, people, and objects, and most
importantly brake operation to ensure safe
operation of the vehicle under all road
conditions. Your complete attention is always
required while driving to maintain safe control
of your vehicle. Failure to follow these
warnings can result in a collision or serious
personal injury.
4

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