Cadillac 2011 DTS Owner's Manual page 171

If the cruise control is already activated,
Press the +RES button. Hold it there until the
desired speed is reached, and then release the
button.
To increase the vehicle speed in small amounts,
briefly press the +RES button and then release it.
Each time this is done, the vehicle goes about
1.6 km/h (1 mph) faster.
The accelerate feature only works after the cruise
control speed is set by pressing the SET button.
If the cruise control is already activated,
Press the SET button until the lower speed
desired is reached, then release it.
To slow down in small amounts, press the SET
button briefly. Each time this is done, the vehicle
goes about 1.6 km/h (1 mph) slower.
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 speed.
When going downhill, you might have to brake or shift
to a lower gear to keep the vehicle speed down. When
the brakes are applied or you shift into a lower gear the
cruise control is disengaged.
There are three ways to end cruise control:
To disengage cruise control, step lightly on the
brake pedal.
Press the button.
Press the button.
4-13