Saab 2000 9-5 - Manual (Page 147)

147 Starting and driving
The ABS system will not reduce the braking
distance on loose gravel or on snow or ice
but, because the wheels cannot lock up,
some steering control is retained.
When the ABS system is working, i.e. mod-
ulation of the brake pressure is in progress,
the brake pedal will pulsate and a ticking
noise will be heard. All this is perfectly nor-
mal.
Press the pedal down hard (you cannot
press too hard) and steer the car to safety.
Do not release the brake pedal before the
car has come to a halt or the danger is
past!
That is critical.
If the road is slippery, the ABS system will
operate even when only light pressure is
applied to the pedal. This means that you
can brake gently to test the condition of the
road and adapt your driving accordingly.
It is well worth practicing the use of ABS
brakes on a skid pan or other suitable facil-
ity.
Traction Control System
How the system works
The traction control system (TCS) is
designed to prevent wheelspin. This
enables the car to achieve the best possible
grip and, hence, maximum tractive effort,
together with greater stability.
The TCS system uses information from the
ABS system’s wheel sensors to detect
when the front (driving) wheels are rotating
faster then the rear wheels. It then monitors
whether one driving wheel is rotating faster
than the other. If so, the faster wheel is
retarded until both wheels are rotating at the
same speed.
If the two front wheels are rotating at the
same speed but are turning faster than the
rear wheels, the torque from the engine is
reduced to eliminate the difference.
The process continues until all the wheels
are rotating at the same speed.
The advantages of the TCS system become
most apparent when the cohesion between
the front wheels and the road surface is so
low that one or both of the wheels would
lose their grip were the car not equipped
with the TCS, e.g.:
• When the car is pulling away or accelerat-
ing with the front wheels on different sur-
faces (e.g. one slippery and one dry). The
TCS then functions like an electronic dif-
ferential lock.
• When the car is pulling away or accelerat-
ing on a slippery road, in which case the
Braking with ABS brakes
When the system is operating, the brake
pedal will pulsate gently and the system
will make a ticking noise
IB476 IB477
Braking with ABS – evasive steering