2001 BMW 325I Owners Manual

177n
IndexDataTechnologyRepairsCar careControlsOverview
Rain sensor
*
Depending on how wet the windshield
is, the rain sensor controls the opera-
tion of the windshield wipers.
Infrared light is carried along the
surface of the windshield in an optical
conductor in such a manner that it is
reflected completely when the wind-
shield is dry. The quantity of reflected
light is measured.
If there is moisture on the glass, the
amount of light reflected is reduced
since the infrared light at the surface of
the windshield can escape. The quan-
tity of reflected light is thus a means of
gauging the degree of wetness on the
windshield.390de133
When the system is set to the "Intermit-
tent" wiper speed, the wipers react
immediately Ð if water is splashed onto
the windshield by vehicles traveling
ahead of you, for example. As a result,
the rain sensor contributes to driving
safety and comfort.

178n
Tire Pressure Control (RDC)
*
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 electronic chip which is
designed for severe-duty applications
and long service life. It contains a pres-
sure 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. 463de006
There is an antenna located right near
every wheel in the vehicle body. This
antenna picks up signals from its
respective wheel. A central electronics
system evaluates the quadruple signals
which it receives and forwards any
changes.
The RDC provides an important contri-
bution to driving safety.

179n
IndexDataTechnologyRepairsCar careControlsOverview
Self-diagnostics 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 also come on
briefly after the ignition has been turned
on.
While you are driving, the functional
status of the actuator motors (for the
windshield wipers, power windows,
seats, sliding/tilt sunroof, etc.) is
constantly analyzed by current
measurements in their relays.460de177
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 fluc-
tuation that would necessarily accom-
pany 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 posi-
tion. This action ensures that the
system will be able to provide
defrosting, regardless of other circum-
stances, e. g. if a malfunction in the air
conditioner/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 move all air condi-
tioner/automatic climate control flaps 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 appropriate adjust-
ments for the operating elements can
be made at any time.You will hear the sounds of the air flaps
as the air conditioning system/auto-
matic climate control carry out their
self-diagnostic functions after the igni-
tion has been turned off. All of the other
self-diagnostics functions operate
silently in the background.
Any possible defects detected during
these self-diagnostics can be read out
by your BMW center and quickly
corrected during the vehicle's next
regularly scheduled maintenance.

180n
Xenon lamps
*
The xenon lamp provides forward illu-
mination with significantly more bright-
ness and uniformity than the traditional
halogen lamp.
In a xenon lamp, an electric arc replaces
the filament in order to generate intense
illumination. A gas mixture in a quartz
glass tube with metal vapor is ignited by
a high electric voltage. The arc that is
generated is then sustained by a lower
voltage. When the lamp is turned on,
there is a brief warm-up period.
Maximum brightness is attained in
approx. 15 seconds.390de134
Xenon lamps provide significantly
improved visibility, especially during
adverse weather and poor driving
conditions e. g. driving at night in heavy
rain or through road repair areas where
there are no lane markers.
Vehicles with xenon lamps are equipped
with an automatic headlamp range
control. Thus the highway is always
optimally lighted and drivers in
oncoming traffic are not blinded.
Xenon lamps make a significant contri-
bution to highway safety since other
highway users, bicyclists and motorcy-
clists in the right lane, and pedestrians
are more easily detected.

181n
IndexDataTechnologyRepairsCar careControlsOverview

182n

Overview
Controls and features
Operation, care
and maintenance
Technical data
Index Advanced technology
183n
IndexDataTechnologyRepairsCar careControlsOverview
Engine data184
Dimensions185
Weights186
Capacities187
Electrical system188
Drive belts188
Data
Owner service procedures

184n
BMW 325i/325xi
Displacement
Number of cylinders cu.in (cmm) 152.2 (2,494)
6
Maximum output
at engine speed hp (kW)
rpm184 (135)
6.000
Maximum torque
at engine speedlb.ft (Nm)
rpm175 (237)
3.500
Compression ratioe
10.5
Stroke
Borein (mm)
in (mm)2.95 (75)
3.31 (84)
Fuel-injection system Digital-electronic engine-management system
Engine data