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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.

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INDEX 'tl
WARNING
Your common sense, good
judgemenl, and general alertness are
crucial to sale and successiul service
worlr. Belore attempting any work on
your
BMM be sure lo read 001
General Warnings and Cautions
and the
copyriglll page at the front 01
the manual. Review these warnings
and
caulions each lime you prepare
lo work on your BMW. Please also
read any warnings and cautions that
accompany
tile procedures in the
manual.
312-way valve (running losses)
see Fuel tank
Abbreviations, commonly used 600-14
ABS (antilock brake system)
see
Bral(es
A/C air distribution motors
see stepper motors (below)
blower final stage (resistor pack),
replacing
640-16
blower, removinglinslalling
640-1 5
compressor, replacing
640-24 condenser, replacing 64045
control panellmodule, removing1
installing
640-1 1
evaporakr, removinglinstalling 640-29
evaporator temperature sensor
640-12 expansion valve, removinglinstailing
640-27
IHKA/ IHKR system description 640-5
receiveridrier, replacing 640-26
stepper motors 640-1 3 ventilation microiilter, replacing
020-22. 640-17
see also Heating
Accelerator
iinlcage
see Maintenance
Activated carbon canister
see Fuel tank
ADS (auxiliary throttle valve)
130-57
Air compressor
330-44
Air conditioning
see
AIC
Air distribution (flap) motors
seeNC, stepper motors
Air filter see Maintenance
Air spring
300-6, 330-12
Airbag system (SRS)
2-stage
airbag 721-4
control module, replacing 721-7 driver airbag, removinglinstalling
721-8
iiead protection airbag 721-12 components 721-1 1
indicator
lighl721-4
passenger airbag, removinglinstalling
721-9 side-impact airbags crash sensor,
replacing
721-7
Airflow sensor see 130 under appropriate
fuel
injection system
Air pump
see 130 under appropriate fuel
injection system, secondary air
injection system
Air suspension
see Electronic height control
(EHC)
Alarm
see Anti-theft alarm
Alignment see
Wheei alignment
Aluminum suspension components
300-2
Antenna 650-6
Alternator see Battery, starter, alte rnator
Amplifier
650-4
Anti-theft alarm (DWA)
515-24 emergency disarming 515-31
Antifreeze (engine coolant)
see Maintenance
see also Cooling system
Antilock brake system (ABS) see Brakes
ASC see Brakes
ATF (automatic transmission fluid)
see Automatic transmission
see also Cooling systern
Automatic headlight adjustmenl
(LWR) see Lights
Automatic seat belt tensioner
720-4
Automatic shiftloclc
see
Gearshift
Automatic transmission
applications
200-3, 240-4
ATF 020-10, 200-4
capacity 240-8 checking 240-6
drainingifilling 240-7
heat exchanger 170-5
fluid pan and strainer 240-9 gearshift
see Gearshift
ID tag
200-3 range switch 610-6
removaliinstallation 240-10
steptronic see Gearshift
Auxiliary cooling fan
see
Coollng system, electric Ian
Auxiliary throttle valve (ADS)
130-57
Axle joint
see Drive axle
Back-up light switch
automatic transmission see Automatic transmission. range switch
- .~.~~~
manual transmission 230-8 -
- I