Srs BMW 528i 1998 E39 Owner's Guide

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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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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.

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721 -8
(Airbag System (SRS)
4 Remove electrical harness connector from crash sensor (A).
Remove sensor retaining screws (6) and remove sensor.
Note direction of sensor before removing.
- Installation is reverse of removal,
NOTE -
Arrow on sensor must point to door sill.
Driver airbag, removing and installing
- Disconnect negative (-) cable from battery and cover nega-
tive terminal with insulating material.
WARNING-
After disconnecting the batter)! wait 5 seconds before begin-
ning work on
airbag components.
CAUTION-
Prior to disconnecting the batter)! read the battery discon-
nection cautionsgiven
in001 General Warnings and Cau-
tions.
4 Multifunction (MFL) steering wheel:
. Working behind steering wheel, completely loosen Torx
screws
(T30) while holding airbag in place.
Support
airbag unit to prevent it from falling out.

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721 -9
Airbaq System ~SRS)~
4 Sport steering wheel:
Insert screwdriver through opening in rear of steering
wheel and push against spring tension to release
airbag
unit lock.
Repeat procedure on other side of steering wheel.
Lift off
airbag unit and detach electrical harness connec-
tors.
WARNING-
Store the removedairbag unit with the horn pad facing up.
If stored facing down, accidental deployment could propel
it violently into the air, causing injury.
Once an
airbag is removed, the car must not be driven.
Do not connect the battery with the
airbag disconnect-
ed. A fault code will be stored, setting off the
airbag in-
dicator light Special tools are needed to reset the fault
memory
Once the
airbag unit is installed and all other service
procedures have been completed, start the engine and
check that the
airbag indicator light goes out. If the in-
dicator light stays on, the
airbag system will not func-
tion as designed. Have the system diagnosed and
repaired by an authorized
BMW dealer.
- Installation is reverse of removal.
MFL steering wheel: Torque airbag using specification list-
ed below.
- Sport steering wheel: Press airbag unit mounting pins into
spring
loclts in steering wheel until they snap in firmly.
CAUTION--
Do notpinch airbag harness in center of steering wheel when
installino
airbaa.
Tightening torque
Airbao to steerino wheel IMFL) 8 Nm (71 in-lb)
Passenger airbag, removing and installing
- Disconnect negative (-) cable from battery and cover nega-
tive terminal with insulating material.
--
WARNING -
After disconnecting the batteg wait 5 seconds before begin-
nina work on airbaa components.
Prior to disconnecting the battery, read the battery discon-
nection cautionsgiven in001 General Warnings and
Cau-

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721 -1 0
/Airbag System (SRS)
4 Pry up cover from top of passenger side airbag on dash-
board.
4 Remove airbag mounting bolts (arrows)
- Lift airbag and disconnect electrical harness connector. Re-
move
airbag.
WARNING-
Store the removed airbag unit with the soft pad facing up. If
stored facing down, accidental deployment could propel it vi-
olentlv into the
ail: causino inium
- Installation is reverse of removal. Make sure wiring harness
is not pinched when installing
airbag unit in dashboard.
Tightening torques
-
Passenger alr bag to 10 NM (88 in-lb)
dashboard (Me)
Door mounted side-impact airbag,
removing and installing
- Disconnect negatlve (-) cable from battery and cover nega-
tive terminal with insulating material.
CAUTION-
Prior to disconnecting the battea read the battery discon-
nection cautions given
in 001 General Warnings and Cau-
tions.
- Remove inside door panel as described in 41 1 Doors