four wheel drive BMW 325Ci CONVERTIBLE 2001 E46 Owner's Manual

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IndexDataTechnologyRepairsCar careControlsOverview
Tire Pressure Control (RDC)
*
The conceptRDC monitors the tire pressures at all
four wheels, even when the vehicle is
moving. The system provides an alert
whenever the inflation pressure drops
significantly below the specified pres-
sure in one or more tires.
In order for the system to "learn" the
correct tire inflation pressure, check the
inflation pressure in all tires according
to the inflation pressure table (page 28)
and make corrections if necessary.
Then activate the system.
This indicator lamp in the instru-
ment cluster will inform you if
the tire pressure is not correct.
Activate the systemDepending on the type of equipment,
the switch either has the letters RDC on
it or the RDC-symbol.
1 Turn ignition key to position 2 (do not
start the engine).
2 Press the switch long enough for the
yellow indicator lamp in the instru-
ment cluster to light up for a few
seconds.
3 After a few minutes driving time, RDC
sets the current inflation pressure in
the tires as the target values to be
monitored.
You will only have to repeat this proce-
dure following a correction of the tire
inflation pressure. Otherwise, RDC
functions automatically when the igni-
tion key is in position 2, and thus oper-
ates whenever the vehicle is driven.46cus046
In the event of loss in tire
pressureIf the inflation pressure has dropped
significantly over a long period of time
(which is normal for any tire), the indi-
cator lamp will come on with a yellow
lamp.
This alerts you to have the tires inflated
to the specified pressures as soon as
possible.
If you are prompted to check the
tire pressure shortly after a
correction has been made, this indi-
cates that the corrected values were
not accurate. Please check the inflation
pressure again and make corrections
according to the inflation pressure
table. Then activate the system once
again.<

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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.46cde078
All
of the important electrical and elec-
tronic systems in the vehicle are tested
regularly and automatically Ð the driver
does not have to perform any extra
operations or adjustments.
The indicator lamps come on brießy
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 ßuctuation that 46cde052
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 ßaps 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 ßaps 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 ßaps 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.