Description: Today, virtually all cars
come with ABS as standard equipment or as an option. The typical ABS
system includes wheel-speed sensors, a hydraulic control unit, and
an electronic control unit. When you apply the brake pedal, the
electronic control unit monitors and compares the signals from the
wheel-speed sensors. If the electronic control unit senses rapid
deceleration (impending lock-up) at a given wheel, the electronic
control unit commands the hydraulic control unit to reduce hydraulic
pressure to that wheel. This type of pressure limiting is similar to
pumping the brake pedal, only much faster. Some pick-up trucks and
cargo vans have rear-wheel only ABS to handle different braking
needs under different loading conditions. This type of ABS system
controls only the rear wheels and limits pressure to both of them
when either is about to lock. Click here to view a
detailed diagram of the brake system.
Purpose: ABS was designed to help you
maintain directional control during emergency stops and when road
conditions are poor. By maintaining control, you have better chances
of avoiding a crash. ABS is especially useful on wet and slippery
roads. You should never pump the brake pedal on a car with ABS,
since the system itself “pumps” the brakes automatically. All you
need to do is apply firm and continuous pressure to the brake pedal
to activate ABS operation. When the ABS system operates,
you may feel a pulsating sensation from the brake pedal.
When ABS operation is no longer
needed,
the braking
system reverts to
conventional hydraulic operation without intervention from the ABS
system.
Maintenance Tips/Suggestions: When turning the ignition switch to the
on position, the amber BRAKE, ANTILOCK or ABS light on the
instrument panel should glow momentarily, and then turn off. If the
light stays on or flashes, or comes on while driving, it indicates a
fault in the ABS system. Have your car’s ABS system inspected
immediately by a professional technician to determine the source of
the problem. Your owner’s manual may specify
periodic
flushing and filling of the brake hydraulic system, which should not be
overlooked. This is a service best left to professional technicians,
as many cars with ABS have specialized
brake-bleeding procedures. Braking systems with ABS can also generate extremely
high hydraulic pressures, which can be dangerous.
Once again, consult a professional service technician if your car
needs ABS or hydraulic system service.
