1998 BMW 528i engine control system

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General ........................... .34 0.2
Special Tools
....................... .34 0.2
E39 brake system
.................... .34 0.4
Electronic braking and stability control
.... .34 0.4
Troubleshooting
..................... .34 0.5
Warnings and cautions
................ .34 0.7
Bleeding Brakes ................... .34 0.8
Brakes, bleeding
..................... .34 0.9
Brake Pads, Calipers and Rotors ... .34 0.1 1
Braking system components .......... .34 0.11
Brake pads,
checking and replacing ..... .34 0.12
Brake rotors, removing and installing
.... .34 0.15
Master Cylinder .................. .34 0.16
Master cylinder, removing and installing
. .34 0.17
Brake Booster .................... .349 0.1
Brake booster check valve
............ .34 0.19
Brake booster, removing and installing
.. .34 0.20
Parking Brake .................... .34 0.22
Parking brake components
............ .34 0.22
Parking
brake, adjusting .............. .34 0.22
Parking bralte shoes, removing
and installing
....................... .34 0.23
Parking
brake cable, replacing ......... .34 0.24
ABS Component Replacement ..... 340-26
Wheel speed sensor. replacing
......... 340-26
ABS impulse wheel
.................. 340-27
DSC lateral acceleration or
rotational rate (yaw) sensor. replacing
... 340-27
DSC steering angle sensor.
removing and installing
............... 340-28
DSC precharge pump.
removing and installing (1998 models)
... 340-29
DSC pressure sensor
(1 999 - 2002 models) ................ 340-30
ABS /traction electronic control
module
(1 997 -1 998 models) .......... 340-31
ABS
/ DSC control module
(1 999
- 2002 models) ................ 340-31
ABS
/ traction control hydraulic unit.
removing and installing
............... 340-31

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This repair group covers brake service:
Brake pads, calipers, and disks
Master cylinder, bralte booster, and parking brake
ABS
1 ASC and ABS / DSC component replacement
ABS
1 ASC and ABS 1 DSC system descriptions are covered
in
300 Suspension, Steering and Brakes - General.
Special Tools
BMW requires the use of either the DIS or the MoDiC diag-
nostic tool to safely and completely bleed the
brak~ng and
traction control systems. Read all procedures through before
beginning a job.
< Parking bralte cable adjusting tool
(Tool No. BMW 34
1 030)
4 Brake piston expander
(Tool No. BMW 34
1 050)
4 Bralte caliper bolt tool (7 mrn Allen)
(Tool No. BMW 34
1 080)
34 I 000
34 1 090 < Steel wire brush
7 (Tool No. BMW 34 1 090)

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E39 brake system
BMW E39 models are equipped with vacuum power-assisted
four-wheel disc brakes with an integral
Antilock Brake System
(ABS). Single-piston calipers act on vented front and rear ro-
tors. A brake pad wear sensor for each axle indicates when
brake pads need replacement. The dual drum-type parking
brake system is integrated with the rear brake rotors.
Electronic braking and stability control
E39 models were introduced with Automatic Stability Control,
a computer controlled traction control system that uses the
AB5 system in conjunction with engine management controls
to control wheel spin during take-off and maintain vehicle sta-
bility while braking.
Added in the
1998 model year was Dynamic Stability Control
(DSC). This system implements wheel speed modulation
throughout all stages of driving. For example, DSC is able to
reduce understeer by applying differing amounts of braking
force to each wheel, or it can override the engine manage-
ment system during hard cornering.
A summary of distinguishing characteristics of the various
systems is shown in the table
E39 electronic braking and
stability control systems.
For ABS, ASC and DSC system and component descriptions,
see
300 Suspension, Steering and Brakes-General.
WARNING-
A car with electronic stability control is still subject to normal
physical laws. Avoid excessive speeds for the road conditions
encountered.
E39 electronic braking and stability control systems
Year (model)
manuf. up to 911998
(528i, 540i)
manuf. from 911999
(540i optional)*
From
911 999
(ail models) System
Automatic Stability Control (ASC) Identifiers
Electronic control module next to glove compartment
Hydraulic unit in right rear of engine compartment
No precharge pump
Dynamic Stability Control
(Bosch DSC
Ill v. 5.3)
Dynamic
Stabil~ty Control
(Bosch DSC
Ill v. 5.7) Electronic
control module next to glove compartment
Hydraulic unit in right rear of engine compartment
Precharge pump in left front of engine compartment, below steering
fluid reservoir
Separate rotational rate (yaw) and lateral acceleration sensors
Control
modulelhydraulic unit in right rear of engine compartment
No precharge pump
Combined rotational rate (yaw) and lateral acceleration sensors

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340-6
1 Brakes
Brake system troubleshooting
/symptom I Probable cause 1 Repairs
Brake squeal
Pedal goes to floor when
bralting
Low pedal after system bleeding
Pedal spongy or brakes work
only when pedal is pumped
Excessive braking effort
Brakes pulsate, chatter or grab
Uneven
bralting, car pulls to one
side, rear braltes
loclt
Brakes drag, bind or overheat Brake
pad carriers dirty or corroded or
pads loose (poor fit) in pad carrier
Braite pads heat-glazed or oil-soaked
Wheel bearings worn (noise most
pronounced when turning)
Incorrectly Installed brake pads,
parking bralte shoes, or bralte parts
Brake fluid loss due to system leaks
Master cylinder or traction control
system faulty
Master cylinder faulty
Air in braite fluid
Master cylinder or traction control
system faulty
Brake pads wet
Brake pads
heat-glazedorfluid-soalted
Vacuum booster or vacuum hose
connections to booster faulty
--- Warped brake rotors
Brake pads worn
Brake pads heat-glazed or oil-soaked Remove
brake pads and clean calipers. Use original
equipment pads for proper fit and use BMW anti-squeal
compound during installation,
Replace brake pads. Ciean rotors. Replace leaking caliper:
as required.
Replace worn bearings. See 310 Front Suspension
or33C
Rear Suspension.
Check component installation. Checldreplace anti-rattle
springs.
Checlt fluid level and inspect for signs of leakage.
Replace master cylinder. Diagnose traction control system
using factory or compatible diagnostic tool.
Replace master cylinder.
Bleed system using factory or compatible diagnostic tool.
Replace master cylinder. Diagnose traction control system
using factory or compatible diagnostic tool.
Use light pedal pressure to dry pads while driving.
Replace
bralte pads and rotors. Replace leaking calipers.
lnspect vacuum lines. Test vacuum booster and replace as
required. Test vacuum non-return valve for one-way flow.
Resurface or replace rotors.
Replace brake pads.
Clean rotors. Replace leaiting calipers.
Incorrect tire pressures or worn tires
Brake pads on one side of car heat-
glazed or fluid-soaked
Caliper or brake pads binding
Worn suspension components
Brake caliper or brake pads binding
Master cylinder or traction control
system faulty lnspect
tire condition. Checlt and correct tire pressures.
Replace brake pads. Clean rotors. Replace leaking
calipers.
Clean and recondition brakes.
Inspect for worn or damaged suspension components. See
310 Front Suspension or 330 Rear Suspension.
Ciean or replace caliper.
Replace master cylinder. Diagnose traction control system
using faclory or compatible diagnostic tool.

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Brakes
Warnings and cautions
WARNING-
. E39 cars require special BMWsen/ice equipment toprop-
erly bleed the brake hydraulic system. See Bleeding
Brakes for additional information.
Semi-metallic and metallic brake friction materials in
brake pads or shoes may produce dangerous dust.
Brake fluid is poisonous, corrosive and dangerous to
the environment. Wear safety glasses and rubber
gloves when worliing with
bralie fluid. Do not siphon
brake fluid with your mouth. Dispose of brake fluid
properly
Do not reuse self-locking nuts, bolts or fasteners. They
are designed to be used only once and may fail if re-
used. Always replace them with new self-locliing fas-
teners.
CAUTlOI\C
Immediately clean bralie fluid spilled on painted surfaces
and wash with water, as
bralie fluid will remove paint.
Always use new brake fluid from a fresh, unopened
container.
Brake fluid will absorb moisture from the air.
This can lead to corrosion problems in the
braking sys-
tem, and will also lower the fluid boiling point.
. Plug open lines and brake fluid ports to prevent con-
tamination.
Only tighten brake hoses on front wheels
with wheels
in straight ahead position.
If carrying out electric welding
worlc, be sure to discon-
nect electrical harness connector from electronic con-
trol module.
Do not expose electronic control modules to high sus-
tained heat, such as in a paint drying booth. Maximum
heat exposure:-95°C (203
OF) for short periods of time-
85'C (185°F) for Ions periods of time (approx. 2 hours)

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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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Brakes
Brakes, bleeding
The procedure below requires a BMW Service Tester (DIS-
pluslGTl/MoDiC).
- Determine type of traction control (ASC, DSC with precharge
pump, DSC without precharge pump). Be sure to use correct
specification brake fluid, according to application table below.
Brake fluid applications
ABS I ASC and ABS / DSC models DOT 4 brake fluid
with precharge pump (to 911998)
ABS I DSC models without precharge DOT 4 low viscosity
pump (911998 and later) brake
fluid
< Remove left side interior ventilation microfilter housing:
Remove upper cover and microfilter loclting clip
(A).
Release locking clamp (B), and rotate air tube in direction
of arrow to remove.
Disconnect wiring harness from hood switch
(C).
Release filter body mounting clamp (D) and remove lower
microfilter housing.
- Top off bralte fluid in reservoir and connect BMW Service
Tester to
20 pin Data Link Connector (DLC) under hood or 16
pin
DLCIOBD I1 connector under dash.
- Call up service function Bleeding ABS / ASC or service func-
tion Bleeding ABS
/ DSC, depending on installed system.
- Fill pressure bleeding device with the correct brake fluid and
connect to brake fluid reservoir and apply pressurize.
Do not exceed a pressure of
2 bar (29 psi) when pressure
bleeding the
brake system. Excessive pressure will damage
4 Starting at right rear wheel, connect bleed hose and fluid re-
ceptacle to bleeder screw (arrow).
CA UTlON-
Bleeder hose must always remain submersed in clean brake
fluid whenever the bleeder valve is open.

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1 Brakes
Max. machine limit per
friction ring side 0.8 mm (0.03
in) I
Brake rotor reconditioning specifications
Model
Replace
braite rotors in pairs
Bralre rotor sizes
Clean rotor with brake cleaner before installing.
Front
Model
6-cylinder
models (5251,
5281, 530i)
V-8 models (540i)
* When installing new rear brake rotors, adjust pariting brake
as described later, in Parking brake, adjusting. Rear
Vented rotor wear limit (min. thickness)
Tightening torques
Braite rotor to hub 16 Nm (12 ft-lb)
6-cylinder models
(525i, 5281, 530i)
- V-8 models (540i)
Front
296 mm (1 1.65 in)
324 mm (12.76 in)
Front bralte pad
carrler to steering ltnucitle 110 Nm (81 ft-lb)
Rear
298 mm (1 1.73 in)
Rear
brake pad carrier to wheel bearing carrier 65 Nm (48 ft-lb)
20.4
mm (0.80 in)
28.4 mm (1.12 in)
Road wheel to hub
120ilONm
(89 -t 7 it-lb)
18.4 mm (0.72 in)
The brake master cylinder is mounted to the front of the vacu-
um booster on the driverside bullthead.
-
CAUTION-
All E39 vehicles soldin the USA are equipped with Antilock
Braling System (ABS) and either Automatic Stability Control
(ASC) or Dynamic Stability Control (DSC).
In order for the
braling and stability controls to work properk if the brake
master cylinder is replaced, make sure that the brake system
is bled
by an authorized BMW dealer or other qualified repair
facility
using the BMW Service Tester. See Brake Bleeding
earlier
in this group.