Owner’s Manual

Black plate (4,1)
GMC Yukon/Yukon XL Owner Manual - 2011
9-4 Driving and Operating
Braking
See Brake System Warning Light on
page 5‑23.
Braking action involves perception
time and reaction time. Deciding
to push the brake pedal is
perception time. Actually doing
it 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
100 km/h (60 mph) travels 20 m
(66 ft). That could be a lot of
distance in an emergency, so
keeping enough space between the
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 the
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. The brakes might not
have time to cool between hard
stops. The brakes will wear out
much faster with a lot of heavy
braking. Keeping pace with the
traffic and allowing realistic
following distances eliminates
a lot of unnecessary braking.
That means better braking and
longer brake life.
If the engine ever stops while the
vehicle is being driven, brake
normally but do not pump the
brakes. If the brakes are pumped,
the pedal could get harder to push
down. If the engine stops, there will
still be some power brake assist but
it will be used when the brake is
applied. Once the power assist is
used up, it can take longer to stop
and the brake pedal will be harder
to push.
Adding non‐dealer accessories can
affect vehicle performance. See
Accessories and Modifications on
page 10‑3.