Drive Systems; All-Wheel Drive; Antilock Brake; System (Abs) - GMC 2010 Acadia Owner's Manual

9-28 Driving and Operating

Drive Systems

All-Wheel Drive

With this feature, engine power is
always sent to all four wheels. It is
fully automatic, and adjusts itself as
needed for road conditions.
When using a compact spare tire
on an AWD vehicle, the system
automatically detects the compact
spare and disables AWD. To restore
AWD operation and prevent
excessive wear on system, replace
the compact spare with a full-size
tire as soon as possible. See
Compact Spare Tire on page 10 77
for more information.
Brakes

Antilock Brake

System (ABS)

This vehicle has the Antilock
Brake System (ABS), an advanced
electronic braking system that helps
prevent a braking skid.
When the engine is started and
the vehicle begins to drive away,
ABS checks itself. A momentary
motor or clicking noise might be
heard while this test is going on,
and it might even be noticed that
the brake pedal moves a little.
This is normal.
If there is a problem with ABS, this
warning light stays on. See Antilock
Brake System (ABS) Warning Light
on page 5 20.
If driving safely on a wet road
and it becomes necessary to slam
on the brakes and continue braking
to avoid a sudden obstacle, a
computer senses that the wheels
are slowing down. If one of the
wheels is about to stop rolling, the
computer will separately work the
brakes at each wheel.
ABS can change the brake pressure
to each wheel, as required, faster
than any driver could. This can help
the driver steer around the obstacle
while braking hard.
As the brakes are applied, the
computer keeps receiving updates
on wheel speed and controls
braking pressure accordingly.