Cadillac XTS Owner's Manual page 201

200 DRIVING AND OPERATING
ACC may detect a vehicle that is not
in your lane and apply the brakes.
ACC may occasionally provide an alert
and/or braking that is considered
unnecessary. It could respond to
vehicles in different lanes, signs,
guardrails, and other stationary
objects when entering or exiting a
curve. This is normal operation. The
vehicle does not need service.
Other Vehicle Lane Changes
ACC will not detect a vehicle ahead
until it is completely in the lane. The
brakes may need to be manually
applied.
Do Not Use ACC on Hills and When
Towing a Trailer
Do not use ACC when driving on steep
hills or when towing a trailer. ACC will
not detect a vehicle in the lane while
driving on steep hills. The driver will
often need to take over acceleration
and braking on steep hills, especially
when towing a trailer. If the brakes are
applied, the ACC disengages.
Disengaging ACC
There are three ways to
disengage ACC:
Step lightly on the brake pedal.
Press .
Press .
Erasing Speed Memory
The cruise control set speed is erased
from memory if is pressed or if
the ignition is turned off.