Air sensor BMW 525i 2001 E39 Workshop Manual

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Body-General
SAFETY AND SECURITY FEATURES
A number of new or improved safety and security features are
incorporated in
E39 cars.
Safety cage
4 The body safety cage is a continuation of an established
BMW concept for passenger protection. Tubular impact
structures built into the body provide protection against pas-
senger injury during front or rear impacts.
Door locks and door handles
4 The door handles allow easy door opening, but are secure in
accidents.
Electrical components in the locks are fully encapsulated and
cannot be picked easily. The door handles, latches and
loclc
assemblies offer reliability and security against theft.
Door position and
loclc condition are detected by hall sensors.
Roof padding
In addition to the side and head protection airbags, there is
supplementary padding at the roof pillars and along the roof
above the doors. This is positioned to present energy absorb-
ing
surlaces to passengers thrown around by side impact
forces.
Seat belts
Each front seat belt assembly has a height-adjustable anchor
at the 8-pillar.
An automatic pyrotechnic (explosive charge) tensioner tight-
ens the front belt at the buckle upon impact, snugging up lap
and shoulder segments of the belt. The tensioners are de-
signed to automatically tension the belts by about
2 inches
(55 mm) in the event ofa collision.
A force limiter puts an upper limit on the amount of iorce each
belt can exert on the passenger.

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400-8
Body-General
Airbags
Front airbags, s~de a~rbags, pyrotechnic seat belt tensioners
and the Battery Safety Terminal (BST) are integrated into the
Supplemental Restraint System (SRS) and its variants.
NOTE-
The BMW SRS system is called Multiple Restra~nt System
(MRS). Over the years,
E39 cars were equipped with MRS,
MRS
11, MRS 111. Each version offers varied features and im-
provements over the previous system.
< As many as 8 airbags may be installed in E39 cars, depend-
ing on model and MRS version.
The front
airbags operate without sodium azide propellant,
widely considered an irritant when an
airbag is deployed.
Starting with
1999 models. "smart"front passenger and driver
airbags were installed. These are of the dual-threshold, dual
stage design, including a
sensorto help prevent the unneces-
sary deployment of the passenger side
airbag if the seat is un-
occupied.
MRS control Depend~ng on options chosen, one airbag may be installed in module each door of the sedan and Sport Wagon models, protecting
passengers against
s~de impacts.
Head Protection System (ITS)
airbags strelch diagonally
across the tops of the front doors.
Airbag deployment automatically triggers fuel shutoff, turns
on the hazard and interior lights, and unlocks the doors.
- -
WARNING -
Airbags are inflated by an explosive device. Handled im-
properly or without adequate safeguards,
airbag units can
be very dangerous. Special precautions must be observed
prior to any worlc at or near any of the airbags. See
721 Air-
bag System (SRS).
Always disconnect the battery and cover the negative
(-) battery terminal with an insulator before starting di-
agnostic, troubleshooting or service work on cars fitted
with SRS, and before doing any welding on the
car.

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Instrument cluster
Instrument cluster uses large easy-to-read analog instru-
ments and is removable as a unit without removing the dash-
board. On-board computer and Check Control functions are
integrated into the instrument cluster displays.
Service Interval Display
Service Interval Display calculates vehicle service needs
based on current driving patterns, and indicates to the driver
when the car requires
service
On-board navigation
An integrated on-board navigation system, based on Global
Positioning System (GPS) technology, is optionally available
on
E39 cars. When installed, a multifunction monitor is includ-
ed in the center of the dash above the radio. in addition to dis-
playing navigation system information, this monitor accesses
On-Board Computerfunctions, audiosystem controls, mobile
phone dialling and memory, and automatic ventilation.
Park Distance Control (PDC)
Park Distance Control (PDC) is an optional system which
uses ultrasonic sensors in the rear bumper trim to warn the
driver of approaching too close to obstacles when parlting.
Central body electronics
E39 vehicles are equipped with an integrated complex of
electronic modules connected mostly via K-Bus. This system,
called central body electronics (ZKE
Ill), is primarily con-
trolled by the general module (GM
Ill). An overview of ZKE Ill
functions is found in 600 Electrical System-General. Details
of ZKE
Ill functioning is in the following repair groups:
- 512 Door Windows
* 515 Central Locking and Aniti-Theft
520 Seats
a 540 Sunroof
611 Wipers and Washers
620 Instruments

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51 2-2
I Door Windows 1
This repair group covers door glass, window regulator and
power window motor repair information.
CA U JIO&
All E39 models are equipped with side-impact airbags in the
front doors. Some models are also equipped with
airbags in
the rear doors. Be sure to read the
airbag warnings and cau-
tions in 721
Airbag System (SRS).
Electric window switch replacement is covered in 612
Switches.
The windshield, rear window, fixed rear doorglass, and cargo
compartment glass (Sport Wagon only) are bonded using
special adhesives and tools. It is recommended that bonded
glass replacement be done by an authorized
BMW service fa-
cility or an automotive glass installer.
Special tools
Some window repair operations require special tools.
Power windows
- Power window features in E39 models include:
Control of the front and rear door window motors is carried
out directly by the General Module (GM
Ill).
One-touch operation in both directions on all four windows.
Cable type window regulator used for all door windows.
. Anti-trap protection provided by pressure sensitive finger
guard.
Right front and each rear door has a single window switch
located in door handle trim.
Rear door window switches can be deactivated by press-
ing child lock-out switch in the driver's window switch block.
Convenience closinglopening of the windows from driver's
loci( cylinder or convenience opening only from remote un-
lociting feature (FZV) remote key.
Window (FZV) operation can be owner customized with
Car Memory function. See 515 Central Locking and Anti-
Theft.
After ignition is switched off, electric windows can be oper-
ated until a door is opened or until
I6 minutes has elapsed.
The GM
IiI bases window motor end position on current
draw (load). There is a maximum window motor run time of
6 seconds. The motor is then switched off even if the end
position load sensor fails.

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721 Airbag System (SRS)
........................... General ............................ 721-2 Airbags 721-8
..... E39Airbags ......................... 721-3 Driver airbag. removing and installing 721-8
Two-stage airbag (MRS 111) ............ .72 1.4 Passenger airbag. removing and installing . 721-9
Airbag indicator light .................. .72 1.4 Door mounted side-impact airbag.
............... Warninas .......................... .72 1.5 removina and installina 721-10 .
..... Head protection airbag components 721
-1 1 Airbag Electronics ................. '721-6 Head protection airbag (HpS) .......... 721-12 MRS ............................... 721-6
MRS
airbag system diagram ........... .72 1.6
MRS control module. replacing ......... .72 1.7
Side-impact crash sensor.
removing and installing
................ .72 1.7

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721 -2
l~irba~ System (SRS)
This repair group covers airbag components and replace-
ment.
Airbag system repairand fault diagnosis is not covered.
Diagnostics, component testing, and
airbag system repair
should be carried out by trained BMW service technicians.
Individual
airbag system components can only be tested elec-
tronically when installed in the car. BMW service testers
DIS
or MoDiC or equivalent must be used for diagnostic work.
WARNING-
Special test equipment is required to retrieve airbag fault
codes, diagnose system faults, and
reseffturn off the air-
bag indicator light. The indicator light will remain on until
any problem has been corrected and the fault memory has
been cleared.
Airbags are part of the BMW Multiple Restraint System
(MRS). Three versions of MRS are available in E39 models.
Multiple Restraint Systems
MRS and MRS II include the following restraint components:
311 996-811 997
911
997-311 999
311 999-2002
Driver and passenger front
airbags (MRSIMRS II)
MRS
MRS
II
MRS Ill
Passenger front two-stage airbag (cars manufactured
from
911998).
The seat occupancy sensor (SBE) is used for detection of
a passenger in the right front seat. MRS uses the SBE in-
put to determine seat belt tensioner
and/or front airbag de-
ployment thresholds.
Side impact
airbag for driver and front passenger
(MRSIMRS II)
Leftlright side impact crash sensors (MRSIMRS 11)
Side impact airbag for rear passenger (MRS II) (optional)
Head Protection System (HPS) for driver and front passen-
ger (MRS
II)
Battery Safety Terminal - BST (MRS II)
Hall Sensor seat belt switches (MRS II)
Front pyrotechnic seat belt tensioners
Fuel pump cut off message

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721 -3
Airbag System (SRS)
MRS Ill adds the following features:
MRS
Ill employs "smart" technology. Smart technology re-
fers to the control module's programming for the deploy-
ment of the airbags, in stages depending on the severity of
the impact.
Two-stage a~rbag for ooln drver and passenger Alloivs for
a softer
c~snioning elfecl when the airbags are lr ggered at
lighter impact,
MRS
Ill satellite sensors use 2 wire connectors
Rear side
airbags arrive de-activated from the factory and
can only be activated upon written request from the cus-
tomer.
Rear seat head protection is available when ordered with
optional rear seat side airbags.
E39 Airbags
Driver airbag
Passenger airbag
Head Protection System (HPS)
Inflatable Tubular Structure
(ITS) (MRS
II and MRS Ill)
Front side impact airbag
Rear door side impact airbag
(optional) (MRS I1 and MRS Ill)

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I Airbag System (SRS)
Two-stage airbag (MRS Ill)
Beginning with 2000 model year (911 999 production) the front
airbags were changed to a two-stage style airbag. This en-
sures that the force of
airbag inflation is not greater than nec-
essary to provide
protection. The airbags are designed to
Drovide "soit" de~lovment if the acceleration sensor detects a
iow-speed impact, and "hard deployment in higher speed im-
pacts.
NOTE-
A two-stage passenger airbag was used on cars built be-
tween
9/1998 and 3/1999. This pre-smart technology airbag
used two ignition stages. Stage one is designed to ignite first
during an impact. Stage two ignites after a timed period, as
programmed in the MRS
I1 control module.
Airbag indicator light
The MRS control module detects and stores system status
The
airbag indicator light in the instrument cluster displays
the status of the
airbag system when the ignition key is in "ac-
cessory" or
ON positions.
System normal: lndicator light comes on briefly, then goes
out.
- System malfunction: lndicator light fails to come on.
System malfunction: lndicator light comes on briefly, goes
out and lights up again.
The
airbag indicator light also comes on if the seat belt pyro-
technic tensioners have been triggered.

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721-6
I Airbag System (SRS)
MRS
The MRS control module contains the electronic crash sensor
for frontal impact. Sensors mounted on the driver and
pas-
sengerfloor are used for side impacts. The MRS control mod-
ule
is located between the front seat under the center
console.
MRS airbag system
diagram
1. Driver's side airbag
2. Passenger's side airbag
3. Right side impact sensor
4. Seat occupancy sensor pad
5. Right side impact airbag
6. SBE control module (analog to
digital converter)
7. Passenger pyrotechnic seat belt
tensioner and seat belt
mi-
croswitch (Hall sensor MRS Ill)
8. MRS control module
9. Driver pyrotechnic seat belt ten-
sioner and seat belt microswitch
(Hall sensor MRS
Ill)
10. Left side impact airbag
11. Left side impact sensor

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Airbag System (SRS)~
MRS control module, replacing
- Disconnect negative (-) cable from battery and cover nega-
tive terminal with insulating material.
CAUTIOI\C
Prior to disconnecting the battery, read the battery discon-
nection cautionsgiven in001 General Warnings and
Cau-
tions.
- Remove center console between front seats. See 513 lnteri-
or Trim.
Remove module mounting nuts (arrows) and lift up control
module. Disconnect electrical harness connector.
Installation is reverse of removal.
Be sure that MRS control module ground cable is attached
to the module mounting stud.
Side-impact crash sensor, removing and
installing
- Make sure ignition key is OFF.
- Remove front seat. See 520 Seats.
Remove plastic door sill trim by lifting to release clips at one
end, then sliding off. Fold up carpet towards rear seat floor. If
necessary, remove floor level heater duct.