Saab 2005 9-3 M, Owner'S Manual

Page: 171 / 292

169 Starting and driving
Traction Control
System (TCS)
Anti-spin 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 uses information from the ABS
wheel sensors to detect when the front (driv-
ing) 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 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
surfaces (e.g. one slippery and one dry),
the TCS functions like an electronic differ-
ential lock, making sure that both wheels
rotate at the same speed.
• When the car is pulling away or accelerat-
ing on a slippery surface, in which case
the system eliminates wheelspin. The
system also functions when the car is
reversing.
• When cornering, if the inside front wheel
rotates faster than the other wheels.
TCS OFF
lights up under the speedometer if:
• a fault has been detected and the system
has therefore been switched off
• there is a fault in the ABS system
• the system has been switched off
manually.
WARNING
When driving normally, the TCS system
helps to improve the car’s directional
stability. The TCS must not be regarded
as a system to enable the driver to main-
tain higher speeds. The same precau-
tions must be adopted as normal for safe
cornering and driving on slippery roads.