Cadillac 2010 DTS Owner's Manual page 179

The vehicle returns to and stays at the preset speed.
If you press and hold the +RES button, the vehicle
speed increases until the button is released or the
brake is applied. Do not hold in the +RES button, if you
do not want the vehicle speed to increase.
There are two ways to go to a higher speed:
Use the accelerator pedal to get to the higher
speed. Press the SET button, then release the
button and the accelerator pedal. The vehicle now
cruises at the higher speed.
Press the +RES button. Hold it there until the
desired speed is reached, and then release the
button. To increase the vehicle speed in very small
amounts, briefly press the +RES button and then
release it. Each time this is done, the vehicle
accelerates approximately 1.6 km/h (1 mph).
The accelerate feature only works after the cruise
control speed is set by pressing the SET button.
There are two ways to reduce the vehicle speed while
using cruise control:
Press the SET button until the lower speed
desired is reached, then release it.
To slow down in very small amounts, push the
SET button briefly. Each time this is done,
the vehicle slows down approximately
1.6 km/h (1 mph).
Use the accelerator pedal to increase the vehicle
speed. When you take your foot off the pedal, the
vehicle slows down to the previous cruise control
speed.
How well your cruise control works on hills depends
upon the vehicle speed, load, and the steepness of
the hills. When going up steep hills, you might have to
step on the accelerator pedal to maintain the vehicle's
speed. When going downhill, you might have to brake
or shift to a lower gear to keep the vehicle's speed
down. Applying the brake or shifting into a lower gear
ends cruise control. If you need to apply the brake or
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