BMW 2001 325CI, Manual

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Tire Pressure Control* Self-diagnostics
This system regularly checks tire pres-
sure and monitors all four tires even
while driving, so you do not have to.
Behind the valve stem in every wheel,
there is an extended-life electronic chip
that contains a pressure sensor, a
transmitter and a battery. The pressure
is measured in extremely short time
intervals and then transmitted by a
radio signal. If an irregularity is
detected, the transmission rate is
increased.
Located near each wheel and
embedded in the vehicle body is an
antenna that receives signals from the
wheel. A central electronics system
evaluates the quadruple signals and
forwards any changes.
The RDC provides an important contri-
bution to driving safety.
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All of the important electrical and elec-
tronic systems in the vehicle are tested
regularly and automatically – the driver
does not have to perform any extra
operations or adjustments.
The indicator lamps come on briefly
after the ignition has been turned on, for
example.
While you are driving, the functional
status of the actuator motors (for the
windshield wipers, power windows,
seats, etc.) is constantly being analyzed
by electrical measurements in the relays.
In the same manner, the electrical
resistance of the airbag ignition genera-
tors and all of the remaining airbag
components is measured at all times. Any
fault in this system would be detected
immediately by a current fluctuation that
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would necessarily accompany it. The fault
would be indicated immediately by the
airbag warning lamp.
Even after you shut off the engine, the
overall functional status of your vehicle is
monitored. For example, all of the flaps of
the heating and ventilation system travel
to the nearest limit position. This action
ensures that the system will be able to
provide defrosting, regardless of other
circumstances, e.g. if a malfunction in the
air conditioner/automatic climate control
system
*
should occur during the night
while the vehicle is parked.
A calibration cycle runs every tenth time
the engine is shut off. During this cycle,
the actuator motors of all the heating and
ventilation flaps travel to their limit stops
in both directions. The limit positions and
the return travel paths are checked in this
manner in order to ensure that appro-
priate adjustments for the operating
elements can be made at any time.
You will hear the sounds of the air flaps as
the air conditioner/automatic climate
control
*
carries out its self-diagnostic
functions after the ignition has been shut
off. All of the other self-diagnostics func-
tions operate silently in the background.
Any possible faults detected during these
self-diagnostics can be read out and
corrected by your BMW center during the
next regularly scheduled maintenance.