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Control of a Vehicle
You have three systems that make your vehicle go where
you want it to go. They are the brakes, the steering, and
the accelerator. All three systems have to do their work at
the places where the tires meet the road.
Sometimes, as when you are driving on snow or ice, it is
easy to ask more of those control systems than the tires
and road can provide. That means you can lose control of
your vehicle. See Traction Control System (TCS) on
page 4-9 and StabiliTrak
®
System on page 4-10.
Adding non-GM accessories can affect your vehicle’s
performance. See Accessories and Modifications
on page 5-3.
Braking
See Brake System Warning Light on page 3-41.
Braking action involves perception time and
reaction time.
First, you have to decide to push on the brake pedal. That
is perception time. Then you have to bring up your foot
and do it. That is reaction time.
Average reaction time is about three-fourths of a second.
But that is only an average. It might be less with one
driver and as long as two or three seconds or more with
another. Age, physical condition, alertness, coordination,
and eyesight all play a part. So do alcohol, drugs, and
frustration. But even in three-fourths of a second, a
vehicle moving at 60 mph (100 km/h) travels 66 feet
(20 m). That could be a lot of distance in an emergency,
so keeping enough space between your vehicle and
others is important.
And, of course, actual stopping distances vary greatly
with the surface of the road, whether it is pavement or
gravel; the condition of the road, whether it is wet, dry, or
icy; tire tread; the condition of your brakes; the weight of
the vehicle; and the amount of brake force applied.
Avoid needless heavy braking. Some people drive in
spurts — heavy acceleration followed by heavy
braking — rather than keeping pace with traffic. This is a
mistake. Your brakes may not have time to cool between
hard stops. Your brakes will wear out much faster if you
do a lot of heavy braking. If you keep pace with the traffic
and allow realistic following distances, you will eliminate a
lot of unnecessary braking. That means better braking
and longer brake life.
If your engine ever stops while you are driving, brake
normally but do not pump your brakes. If you do, the
pedal may get harder to push down. If your engine stops,
you will still have some power brake assist. But you will
use it when you brake. Once the power assist is used up,
it may take longer to stop and the brake pedal will be
harder to push.
Adding non-GM accessories can affect your vehicle’s
performance. See Accessories and Modifications on
page 5-3.
4-6