3 Series E46 320Ci (M54) COUPE
ABS intervention range.
Automatic stability control ASC
ASC prevents the wheels from spinning when the vehicle is accelerating.
Advantage: enhanced traction and the vehicle remains stable.
If one of the wheels of the drive axle is on a high-grip surface and the other is on a slippery surface, the wheel
tending to skid is braked.
ASC is also able to intervene in the engine control (to reduce the ignition angle, injection quantity, throttle valve
setting).
Dynamic traction control DTC
The functions of the DTC correspond to those of DSC with a slightly modified regulating strategy. DTC can be
activated by deactivating DSC (DSC button). DTC intervenes in the braking actions to imitate the function of a
conventional differential lock.
Advantage: higher traction is available with DTC.
Vehicle stabilisation intervention (e.g. reduced power output) is made slightly later than with DSC. This
enhances traction with a slight loss of driving stability. In particular when accelerating and driving uphill on a
loose surface or in deep snow (coefficients of friction requiring increased slip), a compromise is needed between
vehicle stability and traction: DSC provides a high degree of vehicle stability with adequate traction. DTC
provides better traction with a slight loss of stability, and is thus only recommended in exceptional circumstances
(e.g. when driving in deep snow).
Engine drag torque control MSR
Engine drag torque control MSR prevents: the tendency of the drive wheels to lock on a slippery surface when a
lower gear is engaged or load is abruptly changed.
Advantage: the drive wheels retain their lateral stability in overrun mode.
The wheel speed sensors tell MSR as soon as the wheels are about to lock. MSR then briefly reduces the
engine overrun torque by opening the throttle slightly.
Dynamic brake control DBC
DBC supports the driver in emergency braking situations by automatically boosting the brake pressure.
Advantage: shortest possible braking distances in emergency braking situations by achieving ABS regulation on
all four wheels.
The brake pedal is frequently not depressed strongly enough in emergency braking situations. ABS regulation is
then not activated.
The return pump increases the brake pressure until ABS regulation is activated:
-
if the brake pedal is depressed quickly but with insufficient force (from brake pressure sensor signal)
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if the brake pedal is depressed slowly and then rapid deceleration is required (from brake pressure sensor
signal), when one wheel reaches ABS regulation.
Which wheel locks first depends on load and coefficient of friction of the road surface.
Example of a typical situation:
The traffic slows, making light braking necessary at first, but then demands as short a stopping distance as
possible.
Operation
The DSC button is located next to the RPA button (RPA = tyre failure indicator) in the centre console switch cluster.
SBT Dynamic stability control DSC Mk60 E85
BMW AG - TIS
13.02.2013 10:04
Issue status (12/2007) Valid only until next DVD is issued
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