1999 BMW 540i electrical

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340-8
1 Brakes
Brake bleeding is usually done for one of two reasons: either
to replace old brake fluid as part of routine maintenance or to
expel trapped air in the system that resulted
from opening the
brake hydraulic system during repairs.
Read the
Warnings listed below before beginning the bleed-
ing procedure an on any
E39 car. If air enters the ACS or DSC
hydraulic unit, the factory BMW Service Tester MUST be
used in conjunction with a bralte pressure bleeder before the
vehicle is driven.
The BMW
ServiceTester (DISpluslGT1iMoDiC) must be
used to bleed the braltes if:
Any hydraulic brake system components are replaced, in-
cluding bralte lines.
Air has enter the
ABSIASC or ABSlDSC hydraulic unit.
WARNING -
* The ASC and DSC systems use electronic controls and a
sophisticated hydraulic unit Once air enters the hydraulic
unit, it is very difficult to remove using traditional methods.
For this reason, pressure
brake bleeding should be done
in conjunction with the BMW
Sewice Tester (DIS-
plus/GTl/MoDiC). The tester electrically cycles the hy-
draulic unit solenoids in the hydraulic unit while
pressurized brake fluid is forced through the system.
When flushing the brake fluid from the system, use ex-
treme care to not let the
brale fluid reservoir run dry If
air enters the hydraulic unit, the BMW Service Tester
MUST be used to bleed the brale system before the
vehicle is driven.
Always use new brake fluid from an unopened container. It is
important to bleed the entire system when any part of the hy-
draulic system has been opened. Be sure to have the special
equipment needed before beginning the job.
When bleeding the
braltes, start atthe wheel farthest from the
master cylinder and progress in the following order:
right rear brake
left rear brake
* right front brake
left front brake

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1 Brakes
Pull down panel
If applicable, disconnect electrical harness
rows) from 16-pin OBD-ll plug.
Remove panel from interior. connectors
(ar-
Working
above and in front of pedals, remove locking clip (A)
and slide brake booster pushrod off bralte pedal pin. Remove
brake booster mounting nuts
(6).
Working in engine compartment, carefully separate bralte
booster from engine compartment bulkhead.
CAUTION-
Do not use force on booster when separating from bulkhead.
This can damage booster and pushrod.
Remove booster by tilting out in direction of engine. Lift
booster up and out of engine compartment.
- Installation is reverse of removal, noting the following:
Make sure all nuts, fluid couplings, thread bores and mat-
ing surfaces are clean.
Replace bralte booster self-locking mounting nuts.
Replace sealing O-ring between master cylinder and bralte
booster.
Bleed bralte system as described earlier.
CAUTION--
Do not over-torque tlie master cylinder mounting bolts.
This could damage the
bralce booster and prevent proper
vacuum build-up.
After
30 minutes of use recheclc the torque on bralce
booster mounting nuts.
Tightening torques
Brake master cylinder to brake booster
26 Nm (19 it-lb)
Brake booster to bulkhead 22 Nm (16 it-lb)
(Recheck torque after
30 minutes of use.)
Brake fluid line to master cylinder 18 Nm (13 it-lb)
NOTE-
When replacing the brake booster check valve or vacuum
hose, install the valve so that the molded arrow is pointing to-
ward the
fntalce manifold. Use new hose clamps

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4 Disconnect and remove speed sensor electrical harness (ar-
row) from retaining mounts. (Lefl front wheel shown).
- During installation, apply thin coat of StaburagsBNBU 12/K
or equivalent grease to speed sensor and housing.
- Installation is reverse of removal.
Tightening torque
ABS wheel speed sensor to steering knuckle or 8 Nm (6 It-lb)
rear wheel bearing carrier
ABS impulse wheel
The front and rear impulse wheels are integral with the inner
wheel bearing seal and not available as separate part. See
310 Front Suspension or 330 Rear Suspension for wheel
bearing replacement procedures.
DSC lateral acceleration or rotational rate
(yaw) sensor, replacing
DSC system on 1998 cars (Bosch DSC Ill v. 5.3): Lateral ac-
celeration sensor and rotational rate (yaw) sensor are sepa-
rate units, both mounted underneath or in front of driver's
seat.
DSC system on 1999 and later cars (Bosch DSC
Ill v. 5.7):
Lateral acceleration sensor and rotational rate (yaw) sensor
are combined into one unit, located under driver's seat.
- Remove driver's seat. See 520 Seats.
- Lateral acceleration sensor (1 998 models): Remove lower
lefl door pillar trim (driver's
kick panel) to access sensor. Pull
up carpet as necessary to reach sensor harness connector
or fasteners.
4 Rotational rate (yaw) sensor (1998 models): Remove plastic
trim at door sill to access sensor (arrow). Pull up carpet and
move insulation forward as necessary to reach sensor har-
ness connector or fasteners.
- Combined lateral acceleration / rotational rate (yaw) sensor
(1 999 and later models): Remove plastic trim at door sill to
access sensor. Pull up carpet and move insulation forward as
necessary to reach sensor harness connector or fasteners.
- Disconnect electrical harness connector at sensor.
- Combined sensor (1 999 and later models): Remove sensor
bracket mounting screws.

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Remove snap ring from steering shaft.
- Slide steering angle sensor off steering shaft
< Installation is reverse of removal, noting the following.
Take care to line up loclting pin
(arrow) with mount hole in
sensor.
Perform steering angle offset test using BMW scan tools
DISplus, GT1, or MoDiC. Once calibrated, the sensor
sends a confirmation ID code to the DSC control module
to indicate proper calibration.
DSC precharge pump, removing and
installing
(1 998 models)
1998 V-8 cars with Bosch DSC Ill v. 5.3 are equipped with a
DSC precharge pump mounted in the engine compartment.
There is no separate precharge pump in the Bosch DSC
Ill v.
5.7 system (1999 models and later).
WARNING-
E39 cars require special BMWservice equipment to properly
bleed the brakes. Removal of hydraulic components is not
recommended unless this equipment is available. For safety
reasons, the
brake system on cars with ABS must be bled us-
ing the procedures described in this repair group.
- Using a clean syringe, empty brake fluid reservoir.
CAUTIOI\C
Brake fluid is highly corrosive and dangerous to the environ-
ment. Disoose of it
orooerlv.
Working at precharge pump, disconnect hydraulic lines (A)
and electrical harness connector (6). Clean up dripping fluid.
hydraulic unit. Label all
con-

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1 Brakes
- Remove precharge pump mounting bracket fasteners and re-
move pump.
- Installation is reverse of removal, noting the following:
Be sure to replace rubber pump mounts if damaged
01
worn.
Bleed brakes as described earlier.
Tightening torque Brake line
to precharge pump 18 Nrn (13 ft-lb)
DSC pressure sensor (1 999 - 2002 models)
On 1999 and later DSC systems, the DSC pressure sensor is
screwed into the DSC hydraulic unit (right rear of engine com-
partment).
WARNING-
* €39 cars require special BMW service equipment to prop-
erly bleed the brakes. Removal of the
DSCpressure sensor
is not recommended unless this equipment is available. For
safety reasons, the brake system on cars with ABS must be
bled using the procedures described in this repair group.
Switch off ignition and remove
key to male sure brake
system cannot be activated.
- Disconnect electrical harness connector at switch.
- Use BMW special tool 34 5 160 to remove and install sensor.
Inspect threads and sealing surfaces for damage.
* Work quicltly to avoid excessive brake fluid leakage.
Tightening torque
Pressure sensor
to hydraulic 19 Nrn (14ft-lb)
unit
- Reconnect harness connector
- Bleed front brakes as described earlier.
- Press on brakes and check for leaks at sensor.
- Turn on ignition and firmly depress brake pedal. Check that
DSC warning light does not come on.

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340-32
Brakes
The procedure for removing the ABS I ASC or ABS I DSC hy-
draulic unit is similar for all models. The unit is located at the
right rear of the engine compartment.
- Using a clean syringe, empty brake fluid reservoir.
CAUTION-
Brake fluid is highly corrosive and dangerous to the environ-
ment. Dispose of it
properiw
4 Disconnect electrical harness connector (A) at hydraulic unit
(1998 DSC hydraulic unit in V-8 model shown).
Where applicable, detach electrical harness connector to
DSC pressure sensor.
Mark brake lines
(arrows) in relation to their placement on
hydraulic unit. Detach lines from unit using appropriate
sized flare wrench.
Seal open brake fluid lines and bores with suitable plugs to
prevent contamination.
- Carefully push aside brake lines from retainerslgrommets
that may be in the way of hydraulic unit removal. Use care not
to
kink brake lines.
- Remove hydraulic unit mounting screws. Remove hydraulic unit.
- If necessary, separate hydraulic unit from control module.
- Installation is reverse of removal, noting the following:
Check rubber mount for hydraulic unit/control module. Re-
place if damaged.
Make sure all nuts, fluid couplings, thread bores and mat-
ing surfaces are clean.
Avoid bending pins on control module harness connector
when reattaching.
Make sure brake lines are securely seated in grommets
before installing brake lines in hydraulic unit bores.
Bleed brakes using
BMW Service Testeras described earlier.
Tightening torques Brake lines to hydraulic unit
18 Nm (13 ft-lb)
DSC electronic control unit to hydraulic unit 2.9 Nrn (26 in-lb)
(use new screws)
Hydraulic unit to body
8 Nm (6 ft-ib)
Mounting bracket to hydraulic unit 8 Nrn (6 ft-lb)

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400-5
Body-General
Tailgate
The E39 Sporl Wagon tailgate is large with a low sill for easy
cargo loading. The tailgate opens to an angle of
88" mea-
sured from the rear roof pillar (D-pillar) and to a height of
2029
mm (79.8 in) measured from the ground to the upper edge of
the raised tailgate.
The rear window is bonded to a load bearing frame and can
be opened separately from the main tailgate. Tailgatesupport
gas springs are recessed into cavities in the roof.
Tailgate lock system
A mechanical tailgate lock cylinder is not used; the tailgate is
opened by the unlock pad above the license plate, the remote
tailgate switch located in the drivers kick panel, or via
FZV
(Iteyless entry) control.
4 An emergency release mechanism is incorporated into the
latch assembly to open the hatch from the vehicle interior if a
malfunction occurs.
The tailgate lock assembly includes an automatic soft close
(SCA) feature. The electrical operation of SCA is a function of
central body electronics
(ZKE Ill). The SCA actuator is locat-
ed in the rear cowl panel below the tailgate. The actuator is
controlled by a load relay in the General Module. A locking
cam is mounted on an eccentric that is driven by the actuator.
4 The SCA cam always turns in the same direction to open or
close the tailgate. The cam turns
180" to open or to close.
When the cam turns in the up direction the notch in the cam
SCA actuator pushes on a lever on the back of the latch in the tailgate. This
mechanically unlocks the latch. The tailgate is raised up and
can be opened.

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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.