GMC 2003 Sonoma Owner's Manual page 136

Setting Cruise Control
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CAUTION:
If you leave your cruise control on when you
are not using cruise, you might hit a button
and go into cruise when you do not want to.
You could be startled and even lose control.
Keep the cruise control switch off until you
want to use cruise control.
1. Move the cruise control switch to ON.
2. Get up to the speed you want.
3. Press in the SET button located at the end of the
lever and release it.
4. Take your foot off the accelerator pedal.
3-10
Resuming a Set Speed
Suppose you set your cruise control at a desired speed
and then you apply the brake. This, of course, shuts
off cruise control. But you don't need to reset it.
Once you're going about 25 mph (40 km/h) or more, you
can move the cruise control switch briefly from ON to
R/A (Resume/Accelerate).
You'll go right back up to your chosen speed and
stay there.
If you hold the switch at R/A, the vehicle will keep going
faster until you release the switch or apply the brake.
You could be startled and even lose control. So unless
you want to go faster, don't hold the switch at R/A.