GMC SIERRA 2020 Owner's Manual page 250

Pressing RES+ when there is no
longer a vehicle ahead or the
vehicle ahead is pulling away
and the brake is not applied with
cause the ACC to resume.
When it is determined that there is
no vehicle ahead or the vehicle
ahead is beyond the selected
following gap, then the vehicle
speed will increase to the set speed.
Reducing Speed While ACC Is at a
Set Speed
If ACC is already activated, do one
of the following:
Use the brake to get to the
desired lower speed. Release
the brake and press SET . The
vehicle will now cruise at the
lower speed.
Press and hold SET until the
desired lower speed is reached,
then release it.
To decrease the vehicle speed in
smaller increments, press SET
briefly. For each press, the
vehicle goes about 1 km/h
(1 mph) slower.
To decrease the vehicle speed in
larger increments, hold SET .
While holding SET , the vehicle
speed decreases to the next
5 km/h (5 mph) step, then
continues to decrease by 5 km/h
(5 mph) at a time.
The set speed can also be
decreased while the vehicle is
stopped.
If stopped with the brake
applied, press or hold SET until
the desired set speed is
displayed.
Selecting the Follow Distance Gap
When a slower moving vehicle is
detected ahead within the selected
following gap, ACC will adjust the
vehicle's speed and attempt to
maintain the follow distance gap
selected.
Press on the steering wheel to
adjust the following gap. Each press
cycles the gap button through three
settings: Far, Medium, or Near.
Driving and Operating
When pressed, the current gap
setting displays briefly on the
instrument cluster. The gap setting
will be maintained until it is
changed.
Since each gap setting corresponds
to a following time (Far, Medium,
or Near), the following distance will
vary based on vehicle speed. The
faster the vehicle speed, the further
back your vehicle will follow a
vehicle detected ahead. Consider
traffic and weather conditions when
selecting the following gap. The
range of selectable gaps may not be
appropriate for all drivers and
driving conditions.
Changing the gap setting
automatically changes the alert
timing sensitivity (Far, Medium,
or Near) for the Forward Collision
Alert (FCA) feature. See Forward
Collision Alert (FCA) System 0 268.
249