GMC TopKick 2007 Owner's Manual page 147

Reducing Speed While Using
Cruise Control
Press in the button at the end of the lever until you
reach the lower speed you want, then release it.
To slow down in very small amounts, tap the
button briefly. Each time you do this, you'll
go 1 mph (1.6 km/h) slower.
Passing Another Vehicle While Using
Cruise Control
Use the accelerator pedal to increase your speed.
When you take your foot off the pedal, your
vehicle will slow down to the cruise control speed
you set earlier.
Using Cruise Control on Hills
How well your cruise control will work on hills
depends upon your speed, load and the steepness
of the hills. When going up steep hills, you may
want to step on the accelerator pedal to maintain
your speed. When going downhill, you may
have to brake or shift to a lower gear to keep your
speed down. Of course, applying the brake or
clutch takes you out of cruise control. Many drivers
find this to be too much trouble and don't use
cruise control on steep hills.
If your vehicle is equipped with the exhaust brake
option and the exhaust brake is turned on, the
exhaust brake may come on and try to slow down
the vehicle to the set cruise control speed if the
vehicle has accelerated past the set cruise control
speed while going downhill.
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