GMC 2012 Sierra Owner's Manual page 347

Cruise control can be dangerous
where you cannot drive safely at
a steady speed. So, do not use
the cruise control on winding
roads or in heavy traffic.
Cruise control can be dangerous
on slippery roads. On such roads,
fast changes in tire traction can
cause excessive wheel slip, and
you could lose control. Do not use
cruise control on slippery roads.
For vehicles with cruise control, a
speed of about 40 km/h (25 mph) or
more can be maintained without
keeping your foot on the
accelerator. Cruise control does
not work at speeds below about
40 km/h (25 mph).
When the brakes are applied, cruise
control is turned off.
For vehicles with an Allison or
Hydra Matic 6 speed automatic
transmission, see Grade Braking
under
for an explanation of how cruise
control interacts with the Range
Selection Mode, tow/haul and grade
braking systems.
For vehicles with the StabiliTrak
system that begins to limit wheel
spin while you are using cruise
control, the cruise control will
automatically disengage. See
When road conditions allow the
cruise control to be safely used
again, it can be turned back on.
Press to turn the
.
system on or off. The indicator light
is on when cruise control is on and
turns off when cruise control is off.
Press briefly to resume to a
previously set speed, or press and
hold to accelerate.
the speed and activate cruise
control or make the vehicle
decelerate.
Press to set