1998 BMW 528i ECT

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- -
Seat Belts
Front seat belt tensioner, removing and
installing
- Disconnect battery negative (-) cable in trunk.
The
front seat belt loclts are equipped with pyrotechnic (ex-
plosive charge) automatic tensioners. These tensioners are
designed to automatically retract and tension the seat belt by
55 mm (approximately 2 inches) in the event of an accident.
CAUTION-
Prior to disconnecting the battery, read the battery discon-
nection cautions given in
001 General Warnings and Cau-
tions.
WARNING-
Pyrotechnic seat belt tensioners are powerful devices and
should be handled with extreme care. Incorrect handling
can trigger the tensioner and cause injury
BMW recommends that all repair or replacement work
on pyrotechnic devices must be carried out by a quali-
fied BMW technician.
Be sure to disconnect the battery and wait
5 seconds
before attempting to work on pyrotechnic devices.
Pyrotechnic devices cannot be repaired. Always re-
place them.
Never treat pyrotechnic components with cleaning
agents or grease.
- Do not expose pyrotechnic components to tempera-
tures above
75% (167°F).
Pyrotechnic components can only be tested electrically
when installedusing the
BMWService Tester (DISplus,
GTI, or MoDiC).
Do not fire a pyrotechnic gas generatorprior to dispos-
al. It must be fired by a special disposal company or
shipped
back to BMW in the packaging of the new com-
ponent.
During body straightening and welding with an electric
arc welder, always disconnect the battery and the con-
nection to the pyrotechnic gas generators.
- Remove front seat as described in 520 Seats.
-

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Seat ~eltsl
< Remove tensioner cover:
Cut wire ties (A).
Release wiring harness from tensioner cover clip (B).
- Release tensioner cover locks (C) and slide cover down to
remove.
- When reinstalling:
Replace wire ties to relieve tension on pyrotechnic belt
ten-
sioner harness connector.
Tightening torques . -
Front seat to floor (M10) 42 Nm (31 it-lb)
Seat belt to seat 48 Nm (35 It-lb)
Tensioner mounting bracitet
to seat rail 24 Nm (18 it-lb)
Tensioner to mounting bracket 48 Nm (35 it-lb)

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I Seat Belts
a
Front seat belt assembly
1. Seat belt buckle
2. Seat belt stop button
3. Seat belt
4. Seat belt height adjuster
5.
6-pillar cross brace
6. Seat belt reel mounting bolt
7. Seat belt anchor mounting bolt
8. Seat belt lock with pyrotechnic
tensioner
9. Tensioner mounting bolt
Front seat belt reel, removing and installing
(sedan and Sport Wagon models)
- Detach battery negative (-) cable in trunk.
~~-~
Prior to disconnecting the battery, read the battery discon-
nection cautions given in
001 General Warnings and Cau-
l tions. I
- Remove front seat as described in 520 Seats
4 Gently pry up front and rear plastic door sill protector strips
to remove.

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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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Airbag System (SRS)~
Warnings
When servicing airbag equipped cars, the following precau-
tions must be
observed to prevent personal injury.
WARNING-
. If the airbag indicator light is on, there is a risk that the air-
bags will not be triggered in case of an accident Be sure
to have the system inspected and repaired immediately
Airbag(s) are inflated by an explosive device. Handled
improperly or witliout adequate safeguards, the system
can be very dangerous. Special precautions must be
observed prior to any work at or near the airbags.
0 The airbag is a vehicle safety system. Serious injury
may result if system service is attempted by persons
unfamiliar with the BMW
MRS and its approved service
procedures. BMW advises that all inspection and ser-
vice be performed by an authorized BMW dealer.
Always disconnect the battery and cover the negative
(-) battery terminal with an insulator before starting di-
agnostic, troubleshooting or service
work not associat-
ed
with the airbags, and before doing any welding on
the car.
0 After disconnecting the battery, wait 5 seconds before
beginning work on
airbag components.
* If an airbag has been activated due to an accident,
BMW specifies that
airbag components be replaced.
For more information on post-collision
airbag service,
see an authorized BMW dealer.
Do not fire an
airbag unit prior to disposal. It must be
fired by a special disposal company or shipped back to
BMW in the packaging of the new components.
When removing a fired
airbag unit, avoid contact with
the
skin; weargloves. In case ofskin contact, wash with
water.
Do not allow
airbag system components to come in
contact with cleaning solutions or grease. Never sub-
ject
airbag components to temperatures above 167°F
(75°C). When reconnecting the battery, no person
should be inside the vehicle.
Always place an
airbag unit that has been removed
from its
packaging with the paddedside facing upward.
Do not leave an
airbag unit unattended.
0 If the airbag unit or airbag control module has been
dropped from a height of
'/? meter (I//: ft.) or more, the
airbag unit should not be installed.