brake RAM CHASSIS CAB 2021 Repair Manual

STARTING AND OPERATING167
(Continued)
Adaptive Cruise Control (ACC) Operation
The buttons on the right side of the steering
wheel operate the ACC system.
Adaptive Cruise Control Buttons
Does not always fully recognize
complex driving conditions, which can
result in wrong or missing distance
warnings.

Will bring the vehicle to a complete stop
while following a target vehicle and hold
the vehicle for approximately two seconds
in the stop position. At this point, there will
be an “ACC may cancel soon” chime and
warning to the driver. When ACC is
cancelled, the system will release the
brakes and the driver must take over
braking. The system can be resumed when
the target vehicle drives off by releasing
the brake and pushing the resume button
on the steering wheel.

WARNING! (Continued)
You should switch off the ACC system:
When driving in fog, heavy rain, heavy
snow, sleet, heavy traffic, and complex
driving situations (i.e., in highway construc -
tion zones).
When entering a turn lane or highway off
ramp; when driving on roads that are
winding, icy, snow-covered, slippery, or
have steep uphill or downhill slopes.
When towing a trailer up or down steep
slopes.
When circumstances do not allow safe
driving at a constant speed.
WARNING! (Continued)
1 — Adaptive Cruise Control On/Off Button
2 — Fixed Speed Cruise Control On/Off Button
3 — CANCEL
4 — Distance Button
5 — RES (+)
6 — SET (-)
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168STARTING AND OPERATING
Adaptive Cruise Control (ACC) Menu
The instrument cluster display will show the
current ACC system settings. The information it
displays depends on ACC system status.
Push the ACC on/off button until one of the
following appears in the instrument cluster
display:
Adaptive Cruise Control Off
When ACC is deactivated, the display will read
“Adaptive Cruise Control Off.”
Adaptive Cruise Control Ready
When ACC is activated, but the vehicle speed
setting has not been selected, the display will
read “Adaptive Cruise Control Ready.”
Adaptive Cruise Control Set
When the RES (+) or the SET(-) button is pushed,
the display will read “ACC SET.”
When ACC is set, the set speed will show in the
instrument cluster display.
The ACC screen may display once again if any of
the following ACC activity occurs:
System Cancel
Driver Override
System Off
ACC Proximity Warning
ACC Unavailable Warning
The instrument cluster display will return to the
last display selected after five seconds of no
ACC display activity.
Activating Adaptive Cruise Control (ACC)
The minimum set speed for the ACC system is
20 mph (32 km/h).
When the system is turned on and in the ready
state, the instrument cluster display will read
“ACC Ready.”
When the system is off, the instrument cluster
display will read “Adaptive Cruise Control (ACC)
Off.”
NOTE:
You cannot engage ACC under the following
conditions:
When in 4WD Low
When brakes are applied
When the parking brake is applied
When the automatic transmission is in PARK,
REVERSE or NEUTRAL
When the vehicle speed is below the
minimum speed range
When the brakes are overheated
When the driver’s door is open at low speeds
When the driver’s seat belt is unbuckled at
low speed
Electronic Stability Control (ESC) Full Off
mode is active
To Activate/Deactivate
Push and release the Adaptive Cruise Control
(ACC) on/off button. The ACC menu in the
instrument cluster displays “ACC Ready.”
To turn the system off, push and release the
Adaptive Cruise Control (ACC) on/off button
again. At this time, the system will turn off
and the instrument cluster display will show
“Adaptive Cruise Control (ACC) Off.”

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STARTING AND OPERATING169
To Set A Desired ACC Speed
When the vehicle reaches the speed
desired, push the SET (-) button and release.
The instrument cluster display will show the set
speed.
NOTE:
Fixed Speed Cruise Control can be used without
an ACC distance set. To change between the
different modes, push the ACC on/off button
which turns the ACC and the Fixed Speed Cruise
Control off. Pushing the Fixed Speed Cruise
Control on/off button will result in turning on
(changing to) Fixed Speed Cruise Control mode. If ACC is set when the vehicle speed is
below
20 mph (32 km/h), the set speed will default to
20 mph (20 km/h).
NOTE:
Fixed Speed Cruise Control cannot be set below
20 mph (32 km/h).
If either system is set when the vehicle speed is
above 20 mph (32 km/h), the set speed shall
be the current speed of the vehicle. NOTE:
Keeping your foot on the accelerator pedal
can cause the vehicle to continue to accel
-
erate beyond the set speed. If this occurs, the
message “ACC DRIVER OVERRIDE” will
display in the instrument cluster display.
If you continue to accelerate beyond the set
speed while an ACC distance is also set, the
system will not be controlling the distance
between your vehicle and the vehicle ahead.
The vehicle speed will only be determined by
the position of the accelerator pedal.
To Cancel
The following conditions cancel the ACC or Fixed
Speed Cruise Control systems:
The brake pedal is applied.
The CANCEL button is pushed.
An Anti-Lock Brake System (ABS) event
occurs.
WARNING!
Leaving the Adaptive Cruise Control (ACC)
system on when not in use is dangerous.
You could accidentally set the system or
cause it to go faster than you want. You could
lose control and have a collision. Always leave
the system off when you are not using it.
WARNING!
In the Fixed Speed Cruise Control mode
(no ACC distance set), the system will not
react to vehicles ahead. In addition, the
proximity warning does not activate and no
alarm will sound even if you are too close to
the vehicle ahead since neither the presence
of the vehicle ahead nor the vehicle-to-vehicle
distance is detected. Be sure to maintain a
safe distance between your vehicle and the
vehicle ahead. Always be aware which mode
is selected.
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170STARTING AND OPERATING
The gear selector is removed from the DRIVE
position.
The Electronic Stability Control/Traction
Control System (ESC/TCS) activates.
The vehicle parking brake is applied.
Driver seat belt is unbuckled at low speeds.
Driver door is opened at low speeds.
A Trailer Sway Control (TSC) event occurs.
The driver switches ESC to Full Off mode.
The braking temperature exceeds normal
range (overheated).
The trailer brake is applied manually
(if equipped).
The following conditions will only cancel the ACC
system:
Driver seat belt is unbuckled at low speeds
Driver door is opened at low speeds
To Turn Off
The system will turn off and clear the set speed
in memory if:
The Adaptive Cruise Control (ACC) on/off
button is pushed
The Fixed Speed Cruise Control on/off button
is pushed
The ignition is placed in the OFF position
4WD Low is engaged
To Resume
If there is a set speed in memory push the RES
(+) button and then remove your foot from the
accelerator pedal. The instrument cluster
display will display the last set speed.
Resume can be used at any speed above
20 mph (32 km/h) when only Fixed Speed
Cruise Control is being used.
Resume can be used at any speed above 0 mph
(0 km/h) when ACC is active. NOTE: 
While in ACC mode when the vehicle comes
to a complete stop longer than two seconds,
the system will cancel. The driver will have
to apply the brakes to keep the vehicle at a
standstill.
 ACC cannot be resumed if there is a
stationary vehicle in front of your vehicle in
close proximity.
WARNING!
The Resume function should only be used if
traffic and road conditions permit. Resuming
a set speed that is too high or too low for
prevailing traffic and road conditions could
cause the vehicle to accelerate or decelerate
too sharply for safe operation. Failure to
follow these warnings can result in a collision
and death or serious personal injury.

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STARTING AND OPERATING171
To Vary The Speed Setting
To Increase Or Decrease The Set Speed
After setting a speed, you can increase the
set speed by pushing the RES (+) button, or
decrease speed by pushing the SET (-) button.
U.S. Speed (mph)
Pushing the RES (+) button, or SET (-) button
once will result in a 1 mph speed adjustment.
Each subsequent tap of the button results in
an adjustment of 1 mph.
If the button is continually pushed, the set
speed will continue to adjust in 5 mph incre -
ments until the button is released. The new
set speed is reflected in the instrument
cluster display.
Metric Speed (km/h)
Pushing the RES (+) button, or SET (-) button
once will result in a 1 km/h speed adjust -
ment. Each subsequent tap of the button
results in an adjustment of 1 km/h.
If the button is continually pushed, the set
speed will continue to adjust in 10 km/h
increments until the button is released.
The new set speed is reflected in the instru -
ment cluster display. When An ACC Distance Is Also Set: 
When you use the SET (-) button to decel -
erate, if the engine’s braking power does not
slow the vehicle sufficiently to reach the set
speed, the brake system will automatically
slow the vehicle.
 The ACC system applies the brake down to a
full stop when following the vehicle in front.
If your vehicle follows the vehicle in front to
a standstill, your vehicle will release the
brakes two seconds after coming to a
complete stop.
 The ACC system maintains set speed when
driving uphill and downhill. However, a slight
speed change on moderate hills is normal.
In addition, downshifting may occur while
climbing uphill or descending downhill. This
is normal operation and necessary to main-
tain set speed. When driving uphill and
down -hill, the ACC system will cancel if the
braking temperature exceeds normal range
(over -heated).
Setting The Following Distance In ACC

The specified following distance for Adaptive
Cruise Control (ACC) can be set by varying the
distance setting between four bars (longest),
three bars (long), two bars (medium) and one
bar (short). Using this distance setting and the
vehicle speed, ACC calculates and sets the
distance to the vehicle ahead. This distance
setting displays in the instrument cluster display.
Distance Settings

1 — Longest Distance Setting (Four Bars)
2 — Long Distance Setting (Three Bars)
3 — Medium Distance Setting (Two Bars)
4 — Short Distance Setting (One Bar)
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172STARTING AND OPERATING
To adjust the distance setting, push the
Distance Button and release. Each time the
button is pushed, the distance setting increases
by one bar (longer). When the farthest distance
is set, pushing the distance button again will
reset to the shortest distance.

If there is no vehicle ahead, the vehicle will
maintain the set speed. If a slower moving
vehicle is detected in the same lane, the
instrument cluster displays the ACC Set With
Target Detected Indicator Light, and the system
adjusts vehicle speed automatically to maintain
the distance setting, regardless of the set speed.

The vehicle will then maintain the set distance
until:
The vehicle ahead accelerates to a speed
above the set speed.
The vehicle ahead moves out of your lane or
view of the sensor.
The distance setting is changed.
The system disengages. The maximum braking applied by ACC is limited;
however, the driver can always apply the brakes
manually, if necessary. NOTE:
The brake lights will illuminate whenever the
ACC system applies the brakes.
A Proximity Warning wil l alert the driver if ACC
predicts that its maximum braking level is not
sufficient to maintain the set distance. If this
occurs, a visua l alert “BRAKE” will flash in the
instrument cluster display and a chime will
sound while ACC continues to apply its
maximum braking force.
NOTE:
The “BRAKE!” screen in the instrument cluster
display is a warning for the driver to take action
and does not necessarily mean that the
Forward Collision Warning system is applying
the brakes autonomously. Overtake Aid
When driving with ACC engaged and following a
vehicle, the system will provide an additional
acceleration up to the ACC set speed to assist in
passing the vehicle. This additional
acceleration is triggered when the driver
utilizes the left turn signal and will only be
active when passing on the left hand side.
ACC Operation At Stop
If the ACC system brings your vehicle to a
standstill while following the vehicle in front,
your vehicle will resume motion without any
driver intervention if the vehicle in front starts
moving within two seconds.

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Trailer Detect — If Equipped
When a trailer is detected, the ACC system
automatically defaults to the longest setting
(four bars). The setting can be overridden by
pushing the Distance Button on the steering
wheel.

STARTING AND OPERATING173 If the vehicle in front does not start moving
within two seconds of your vehicle coming to a
standstill, the ACC with Stop system will
cancel and the brakes will release. A cancel
message will display on the instrument cluster
display and produce a warning chime. The
driver must now manually operate the
vehicle's accelerator and brakes.
While ACC is holding your vehicle at a
standstill, if the driver seat belt is unbuckled
or the driver door is opened, the ACC system
will cancel and the brakes will release. Driver
intervention will be required at this moment.
Display Warnings And Maintenance
“Wipe Front Radar Sensor In Front Of Vehicle”
Warning
The “ACC/FCW Unavailable Wipe Front Radar
Sensor” warning will display and a chime will
sound when conditions temporarily limit system
performance.
This most often occurs at times of poor visibility,
such as in snow or heavy rain. The ACC system
may also become temporarily blinded due to
obstructions, such as mud, dirt or ice. In these
cases, the instrument cluster display will display
“ACC/FCW Unavailable Wipe Front Radar
Sensor” and the system will deactivate.

This message can sometimes be displayed while
driving in highly reflective areas (i.e. ice and snow, or
tunnels with reflective tiles). The ACC system will
recover after the vehicle has left these areas. Under
rare conditions, when the radar is not tracking any
vehicles or objects in its path this warning may
temporarily occur.
NOTE:
If the “ACC/FCW Unavailable Wipe Front Radar
Sensor” warning is active, Fixed Speed Cruise
Control is still available.

If weather conditions are not a factor, the driver
should examine the sensor. It may require
cleaning or removal of an obstruction. The sensor
is located in the camera in the center of the
windshield, on the forward side of the rearview
mirror.

To keep the ACC system operating properly, it is
important to note the following maintenance
items:
Always keep the sensor clean. Carefully clear
the windshield.
Do not remove any screws from the sensor.
Doing so could cause an ACC system
malfunction or failure and require a sensor
realignment.
Do not attach or install any accessories near
the sensor, including transparent material or
aftermarket grilles. Doing so could cause an
ACC system failure or malfunction.
WARNING!

When the ACC system is resumed, the driver
must ensure that there are no pedestrians,
vehicles or objects in the path of the vehicle.
Failure to follow these warnings can result in a
collision and death or serious personal injury.

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STARTING AND OPERATING175
Service ACC/FCW Warning

If the system turns off, and the instrument cluster
displays “ACC/FCW Unavailable Service
Required” or “Cruise/FCW Unavailable Service
Required”, there may be an internal system fault
or a temporary malfunction that limits ACC
functionality. Although the vehicle is still drivable
under normal conditions, ACC will be temporarily
unavailable. If this occurs, try activating ACC
again later, following an ignition cycle. If the
problem persists, see an authorized dealer.

Precautions While Driving With ACC
NOTE:
Aftermarket add-ons such as snow plows, lift
kits, and brush/grille bars can hinder module
performance. Ensure the radar/camera has
no obstructions in the field of view.
Height modifications can limit module perfor -
mance and functionality.
Do not put stickers or easy passes over the
camera/radar field of view.
Any modifications to the vehicle that may
obstruct the field of view of the radar/camera
are not recommended.
In certain driving situations, ACC may have
detection issues. In these cases, ACC may
brake late or unexpectedly. The driver needs
to stay alert and may need to intervene.
The following are examples of these types of
situations:
Towing A Trailer
ACC while towing a trailer is recommended only
with an Integrated Trailer Brake Controller.
Aftermarket trailer brake controllers will not
activate the trailer brakes when ACC is braking. Offset Driving
ACC may not detect a vehicle in the same lane
that is offset from your direct line of travel, or a
vehicle merging in from a side lane. There may
not be sufficient distance to the vehicle ahead.
The offset vehicle may move in and out of the
line of travel, which can cause your vehicle to
brake or accelerate unexpectedly.

Offset Driving Condition Example

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176STARTING AND OPERATING
Turns And Bends
When driving on a curve with ACC engaged, the
system may decrease the vehicle speed and
acceleration for stability reasons, with no target
vehicle detected. Once the vehicle is out of the
curve the system will resume your original set
speed. This is a part of normal ACC system
functionality.
NOTE:
On tight turns ACC performance may be limited.
The driver must maintain control of the vehicle,
remain alert, and be ready to apply the brakes if
needed.

Turn Or Bend Example
Using ACC On Hills

When driving on hills, ACC may not detect a vehicle
in your lane. Depending on the speed, vehicle load,
traffic conditions, and the steepness of the hills,
ACC performance may be limited.

NOTE:
The driver must maintain control of the vehicle,
remain alert, and be ready to apply the brakes if
needed.

ACC Hill Example
Lane Changing

ACC may not detect a vehicle until it is completely
in the lane in which you are traveling. In the
illustration shown, ACC has not yet detected the
vehicle changing lanes and it may not detect the
vehicle until it's too late for the ACC system to
take action. ACC may not detect a vehicle until
it is completely in the lane. There may not be
sufficient distance to the lane-changing vehicle.
Always be attentive and ready to apply the brakes
if necessary.
Lane Changing Example

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STARTING AND OPERATING177
Narrow Vehicles
Some narrow vehicles traveling near the outer
edges of the lane or edging into the lane are not
detected until they have moved fully into the
lane. There may not be sufficient distance to the
vehicle ahead.

Narrow Vehicle Example
Stationary Objects And Vehicles

ACC does not react to stationary objects and
stationary vehicles. For example, ACC will not react
in situations where the vehicle you are following
exits your lane and the vehicle ahead is stopped in
your lane. Always be attentive and ready to apply the
brakes if necessary
Ú

page 449.

Stationary Object And Stationary Vehicle Example
PARKSENSE FRONT/REAR PARK ASSIST —
IF EQUIPPED

The ParkSense Park Assist system provides visual
and audible indications of the distance between the
rear, and/or front fascia/bumper, and a detected
obstacle when backing up or moving forward (e.g.
during a parking maneuver). For limitations of this
system and recommendations, see
Ú
page 182.

ParkSense will retain the system state (enabled
or disabled) from the previous ignition cycle
when the ignition is placed in the ON/RUN
position.
ParkSense can be active only when the gear
selector is in REVERSE or DRIVE. If ParkSense is
enabled at one of these gear selector positions,
the system will remain active until the vehicle
speed is increased to approximately 7 mph
(11 km/h) or above. A warning will appear in the
instrument cluster display when the vehicle is
in REVERSE, indicating the vehicle is above
ParkSense operating speed. The system will
become active again if the vehicle speed is
decreased to speeds less than approximately
6 mph (9 km/h).
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