1998 BMW 740I sensor

90n
Park Distance Control (PDC)
*
The PDC assists you when you are
parking. Acoustic signals warn you
of the distance to an obstacle. In addi-
tion, four ultrasonic sensors in each the
front and rear bumpers measure the
distance from the nearest object. The
monitoring range for the four front sen-
sors and that of the two rear corner
sensors ends approx. 2 feet (60 cm)
beyond the respective bumper. The two
center sensors cover a distance of
approx. 5 feet (1.50 m).380de619
The system starts to operate automati-
cally about one second after you move
the selector lever to "R" when the igni-
tion key is in position 2. It is similarly
deactivated when you move the selec-
tor lever position from the "R" position.
The indicator lamp in the button (arrow)
comes on to signal the active status.
Manual activation/deactivation is possi-
ble using the button in the center
console (arrow) (indicator lamp comes
on/goes out). The system deactivates
once the vehicle travels approximately
160 ft (50 m) or exceeds a speed of
about 18 mph (30 km/h). It must then be
switched on again as desired.
Acoustical signalsThe distance to an obstruction in the
front is indicated by a higher interval
tone, while the distance to an obstruc-
tion in the rear is indicated by a deeper
tone. As the distance between vehicle
and object decreases, the intervals be-
tween the tones become shorter. A
continuous tone indicates the presence
of an object less than 1 ft. (30 cm)
away.
The warning signal is canceled after ap-
prox. three seconds if the distance to
the obstruction remains constant during
this time (if you are moving parallel to a
wall, for instance).
System malfunctions are indicated by a
short, continuous tone and a flashing
indicator lamp (indicator lamp only
when the system is activated by shifting
the transmission into "R").
Switch the system off and consult an
authorized BMW center to have the
problem corrected.

91n
RepairsIndexOverview Controls Car care Technology Data
Park Distance Control (PDC)
*
The PDC does not remove the
driver's personal responsibility for
evaluating the distance between the ve-
hicle and any obstacles. Even when
sensors are involved, there is a blind
spot in which objects cannot be de-
tected. This applies especially in those
cases where the system approaches
the physical limits of ultrasonic mea-
surement, as occurs with tow bars and
trailer couplings, and in the vicinity of
thin and painted objects.
Certain sources of sound, such as a
loud radio, could drown the PDC signal
tone.<
Keep the sensors clean and free
of ice or snow in order to ensure
that they continue to operate effectively.
Do not apply high-pressure spray to the
sensors for a prolonged period of time.
Maintain an adequate distance of more
than approx. 4 inches (10 cm).<

124n
Catalytic converterThe catalytic converter reduces harmful
exhaust emissions, and is designed for
use with unleaded fuel only.
Even minute quantities of lead would be
enough to permanently damage both
the catalytic converter and the system's
oxygen sensor.
To ensure efficient, trouble-free engine
operation and avoid potential damage:
>Be sure to comply with the scheduled
maintenance requirements
>Fill the fuel tank well before it is
empty
>If you have problems starting the en-
gine, use jumper cables (you cannot
tow-start the vehicle with an auto-
matic transmission)>Avoid other situations in which the
fuel is not burned, or burns incom-
pletely, such as engaging the starter
frequently or for extended periods, or
repeated start attempts in which the
engine does not start (stopping and
restarting an engine which is running
properly does not present a problem).
Never let the engine run with any of
the spark plug cables disconnected.Be sure to comply with the in-
structions above to prevent un-
burned fuel from reaching the catalytic
converter. Otherwise there is danger of
overheating and damage to the cata-
lytic converter.
Extreme temperatures occur at the
catalytic converter on this and every
catalyst-equipped vehicle. Heat shields
are installed adjacent to some sections
of the exhaust system. Never remove
these shields; do not apply undercoat-
ing to their surfaces. When driving,
standing at idle, and parking the vehi-
cle, take care to avoid contact between
the exhaust system and flammable ma-
terials (grass, hay, leaves, etc.). Such
contact could lead to a fire, resulting in
personal injury and property damage.<

150n
Caring for your carWashing your carYou can have your new BMW washed
in an automatic car wash. Car wash
systems that do not employ brushes are
preferable.
Wipe away tough dirt and loosen and
remove dead insects before washing
the car.
To prevent spots, avoid washing when
the hood is still warm, or immediately
after and during exposure to strong
sunlight.
When using an automatic car wash, be
sure that:
>The car wash system is suited for the
dimensions of your vehicle
>No damage will occur on vehicles
with attached body accessories (such
as spoilers or antennas). If you are
uncertain, consult the manager of the
car wash
>The wheels and tires of your vehicle
cannot be damaged by the convey-
ance devices of the car wash system
>The vehicle is cleaned with minimum
brush pressure, and that ample water
is available for washing and rinsing.Vehicles with rain sensor
*:
Clean the windshield regularly. Wax
from automatic car washes or insects,
for example, can cause malfunctions in
the function of the rain sensor.
Turn the rain sensor off in auto-
matic car washes. If you do not,
damage may occur if the wipers switch
on unintentionally.<
Parts of the car which are inaccessible
to the automatic washer - such as door
sills, door and hood edges, etc. -
should be cleaned by hand.
In the winter months, it is especially im-
portant to ensure that the car is washed
on a regular basis. Large quantities of
dirt and road salt are difficult to remove,
and they also cause damage to the ve-
hicle.
If spray wands or high-pressure
washers are used, be sure to
maintain an adequate distance between
the spray source and the vehicle's sur-
face.
Inadequate distance and excessive
pressure can damage or weaken the
finish, making it more susceptible to
subsequent attack. In addition, mois-
ture could penetrate to vehicle compo-
nents, leading to long-term damage.<
When cleaning the headlamps,
please observe the following:
>Do not clean by wiping with a dry
cloth (scratches). Never use abra-
sives or strong solvents to clean the
covers
>Remove dirt and contamination
(such as insects) by soaking with
BMW Car Shampoo and then rinsing
with plenty of water
>Always use a deicer spray to remove
accumulated ice and snow – never
use a scraper.<
After washing the car, apply the
brakes briefly to dry them. Braking
efficiency might otherwise be reduced
by the moisture, and the brake rotors
could also be corroded.<

184n
Deceleration sensors continuously
monitor the physical forces acting upon
the vehicle. In a severe frontal collision,
the gas generators of the driver's airbag
and the front passenger airbag are ig-
nited. However, the passenger-side air-
bag is only triggered if an additional
sensor has recognized that the passen-
ger seat is occupied.
In the event of a severe side impact, the
head protection and side airbags in the
front and/or rear
* are triggered.
390de319
The airbags located under the marked
covers inflate and unfold in a matter of a
few milliseconds. In this process they
tear through the rated breaking points
of the upholstered covers or press them
out.
Because the inflation process must be
virtually instantaneous, it is necessarily
accompanied by a certain amount of ig-
nition and inflation noise. The gas which
the system employs to inflate the airbag
is not dangerous, and the associated
smoke is quickly dissipated.
The entire process is completed within
fractions of a second.On vehicles with automatic transmis-
sion Adaptive Transmission Control
(ATC) uses a number of factors to cal-
culate the maximally efficient gear. In
this process it monitors your personal
driving style, the situation in which you
are driving, the condition of the road
and the traffic conditions.
ATC recognizes your personal driving
style from the positions and movements
of the gas pedal, declaration when
braking and lateral acceleration through
curves. Four shift characteristics – from
comfort-oriented to performance-ori-
ented – are available for selection by
ATC.
390de048
ATC
Airbags ATC

185n
RepairsIndexOverview Controls Car care Technology Data
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
downshifts 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, and 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. Position
"2" is best for driving on steep mountain
slopes with a heavy load.Precision sensors monitor the number
of revolutions of the wheels. When
equipped with DSC, they also monitor
steering angle, lateral acceleration,
brake pressure and the movement of
the vehicle around its vertical axis.
If differences in the wheel speeds oc-
cur, the system counteracts the danger
of wheelspin by reducing torque. If nec-
essary, the system also responds with
additional applications of the brakes at
the rear wheels.
If the system detects an instability in the
vehicle's condition, the braking action
can also be directed to the front wheels
by the DSC in order to stabilize the ve-
hicle.
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
*

188n
Rearview mirror with automatic dimmerThe interior rearview mirror with auto-
matic dimming feature reduces glare
from following traffic by adapting the in-
tensity of the reflected images to corre-
spond to levels of light registered by the
unit's sensors. The mirror reverts to its
undimmed setting as soon as the light
source disappears. One of these sen-
sors is mounted on the front of the mir-
ror housing and is designed to monitor
light levels in the area immediately for-
ward of the vehicle. The second sensor
is integrated within the mirror's glass.
The electronic control system operates
by comparing the respective levels of
luminous intensity in front of and behind
the car. The difference provides the ba-
sic parameter used to modulate an
electrical current and induce chemical
changes in a semisolid layer incorpo-
rated in the lens. 390de113
The semisolid reacts chemically to this
electrical current, thus providing infi-
nitely-variable dimming of the mirror
(electrochromic technology).
As a result, it is no longer necessary to
dim the mirror manually, and the driver
can maintain full concentration on traf-
fic.

189n
RepairsIndexOverview Controls Car care Technology Data
Tire Pressure Control (RDC)
*
The Tire Pressure Control system as-
sumes the task of regular tire pressure
checks for you. Tire pressures are mon-
itored at all four wheels, even when the
vehicle is moving.
Behind the valve stem in every wheel,
there is an electronic chip which is de-
signed for severe-duty applications and
long service life. It 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 de-
tected, the transmission rate is in-
creased.380de673
Near every wheel, there are antennas in
the body which receive the signals from
all four wheels. 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.