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189n
Index Data Technology Repairs Car care Controls Overview
In order to take driving conditions into
account, ATC registers corners and
both uphill and downhill gradients. For
example, if you maintain speed through
a curve, the transmission does not up-
shift.
On uphill gradients, it shifts only when
the engine speed increases in order to
make more efficient use of power re-
serves. On downhill gradients, ATC
shifts down when the speed of the vehi-
cles increases, causing the driver to
step on the brakes.
With respect to road conditions, ATC
monitors the friction between the tires
and the road. The system responds to
slippery road surfaces (snow and ice)
by activating the winter program.
Second gear is used when moving
away from a standstill, upshifts occur
sooner. On descents, downshifting
does not occur in spite of the applica-
tion of brakes. This enables you to
"feel" the road as you drive and pro-
duces greater dynamic stability. If the
friction between the tires and the road
is adequate, the normal system is again
activated. The system also leaves the
winter program when you shift from
drive position "D" to "S," "3" or "2," or if
the ASC+T/DSC
* is deactivated.
By recognizing traffic conditions, ATC
can retain maximum driving comfort.
For instance, the system recognizes
stop-and-go traffic and then proceeds
only in second gear until it encounters
higher starting loads.
Of course, the selector lever can still be
used to select specific gear ratios. Per-
formance-oriented driving is enabled by
shifting from drive position "D" to "S,"
"3" or "2." Positions "3" and "2" each
limit upshifts to the next gear. Posi-
tion "2" is best for driving on steep
mountain slopes with a heavy load.
Precision sensors monitor the wheel
speeds. The DSC also monitors steer-
ing angle, lateral acceleration, brake
pressure and the movement of the vehi-
cle around its vertical axis.
If differences in wheel speeds occur,
the system recognizes the danger of
wheelspin and reduces the engine's
drive torque. If necessary, the system
also responds with additional braking
intervention at all four wheels.
In addition, DSC permanently monitors
the vehicle's current operating condi-
tion and compares it with an ideal con-
dition that is calculated from the sensor
signals. If discrepancies from this ideal
condition (understeering or oversteer-
ing, for example) occur, DSC stabilizes
the vehicle in fractions of a second by
reducing engine power output and with
the assistance of braking intervention at
individual wheels. Dangerous skids are
thus prevented from the very beginning.
You may need some time to become
accustomed to this system intervention.
However, it helps provide optimum pro-
pulsive force and driving stability.
The braking intervention may be ac-
companied by a certain degree of
noise.
ATC ASC+T/DSC
Online Edition for Part No. 01 41 0 004 597 - © 08/99 BMW Group
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