2001 BMW 530i DSC

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Suspension, Steering and Brakes - General
WHEELS AND TIRES
Tire size is critical to the properoperation of the antilock brake
system and traction control system. Several differentstyles of
wheels in
15,16, and 17 inch diameters are available from an
authorized BMW dealer.
Rim and tire size applications are listed in the table below.
Rim and tire sizes table
ELECTRONIC BRAKE AND STABILITY
CONTROL SYSTEMS
Model
5251
5281
530i
540i (manual
transmission)
540i (automatic
transmission)
All
E39 vehicles are equipped with the Antilock Braking Sys-
tem
(ABS). Early production models featured ABS with Auto-
matic Stability
control (ABSIASC). Later models came
equipped with ABS and Dynamic Stability Control
(ABSIDSC). DSC builds upon the existing ABSIASC system
to provide electronic control of drive and braking systems to
insure vehicle stability.
This manual will refer to these systems as ABS. ASC or DSC
will be specified when necessary. ABS component replace-
ment is covered in
340 Brakes.
Standard
ABS applications are shown in the accompanying table
Rim size
16x7
15x7
16x7
17x8
16x7 Optional
Tire size
225160R-15
235145-1 7
225155-1 6
Rim size
17x8
Front 17
x 8 Rear 17 x 9
17 x 8
Front 17x8
Rear 17x9
Front 17 x 8
Rear 17 x 9 Tire
size
245145R-17
Front 235145-1 7
255140R-17
235145R-17
Front 235145-1 7
Rear
255140R-17
Front 235145-17
Rear 255140R-17

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300-1 2
I Sus~ension, Steerincl and Brakes - General
E39 electronic brake and stability control
systems application table
(528i, 54bi) Traction (ASC) I Hydraulic unit in right rear of engine compartment 1
Identifiers
Year (model)
I No precharge pump 1
Manuf. up to 911998 l~utomatic Stability Control plus I Electronic control module next to glove compartment
System
Precharge pump in
lefl front of engine compartment, below
steering fluid reservoir
Separate rotational rate (yaw) and lateral acceleration sensors
I I
Combined rotational rate (yaw) and lateral acceleration sensors
Electronic control
module next to glove compartment
Hydraulic unit in right rear of engine compartment
Manuf. up to 911999
(540i optional)
I I
ABS system
Dynamic Stability Control (Bosch
DSC
Ill v. 5.3)
The electronically controlled
ABS maintains vehicle stability
and control during emergency braking by preventing wheel
lock-up.
ABS provides optimum deceleration and stability dur-
ing adverse conditions. It automatically adjusts brake system
hydraulic pressure at each wheel to prevent wheel lock-up.
Control
moduleihydraulic unit
in right rear of engine compartment
No precharge pump
Manuf. from
911999
(all models)
Automatic Stability Control (ASC)
Dynamic Stability Control (Boscli
DSC Ill v. 5.7)
NOJE-
ASC (Automatic Stability Control) may also be referred to as
ASCiT (Automatic Stability ControkTraction).
ASC works in conjunction with ABS and the engine manage-
ment system to enhance vehicle control. The main function of
the
ASC system is to maintain the contact between the tires
and the road surface under all driving conditions. This is
achieved through exact application and management of brak-
ing and drivetrain forces.
The
ASC system improves traction by electronically applying
the rear brakes when the rear drive wheels are spinning at a
faster rate than the front wheels. The combined
ABSIASC
control module, operating through the ABS hydraulic control
unit, modulates braking force at the rear wheels.
In addition,
ASC overrides the throttle opening to reduce en-
gine torque and maintain vehicle traction. Because the throt-
tle is controlled electronically, the driver cannot increase
engine power output during
ASC intervention regardless of
how far the accelerator pedal is pushed.

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Suspension, Steering and Brakes - ~enerail
The main components of the system are the wheel speed
(pulse) sensors, the
ABSIASC or ABSIDSC control module,
and the hydraulic control unit.
Traction control also comes into operation during decelera-
tion. Decelerating on snowy or icy road surfaces can lead to
rear wheel slip. If a rear wheel starts to drag or lock up, the
ASC system can limit the problem by adjusting throttle, fuel
injection and ignition timing.
4 A switch (arrow) on the center console is used to toggle the
ASC on or off.
NOJE-
Even with the ASC system turned off, if the ASC control mod-
ule senses a difference in wheel speed (one wheel spinning)
the
ASC system applies modulated braling force to the slip-
ping wheel until traction is regained. There is no override of
fuelinjection function.
The ASC system is designed to be maintenance free. There
are no adjustments that can be made. Repair and trouble-
shooting of the ASC system requires special test equipment
and knowledge and should be performed only by an autho-
rized
BMW dealer.
ABSIASC traction
I 1.
control system
Wheel speed sensor
Wheel speed pulse wheel
Brake disk
Brake caliper
ABSIASC hydraulic unit
Brake master cylinder
Pedal operated throttle valve
ASC controlled throttle valve
Engine control module (ECM)
Accelerator pedal
ABSlASC control module

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300-1 4
I Susoension. Steerina and Brakes - General
DSC system I
Dynamic Stability Control (DSC)
Dynamic Stability Control (DSC) utilizes many principles and
components of the ASC traction control system. DSC is ac-
tive throughoutthe driving range, unlike ASC which is only ac-
tive during acceleration and braking. DSC helps stabilize the
vehicle in cornering and avoidance maneuvers by adjusting
engine controls such as throttle, ignition, fuel injection and the
application of
brake pressure individually to the wheels.
Inputs
fi- 0
2 4-* .. o
[11-' IJ
411m4
3?-
G
4 The DSC control module uses various inputs to determine
vehicle instability during braking, cornering, or reduced trac-
tion situations. Based upon these inputs the ABSIDSC con-
trol module sends outputs to the engine control module and
the ABSIDSC hydraulic unit to activate torque reduction pro-
tocols and braking intervention.
-
ABSIDSC control module
OUI~YIS
4
The DSC system can be toggled on and off by a switch
mounted on the center console. Turning off the DSC system
does not disable ABS or ASC functions.
+
Measure ride height (A) from center of fender arch to bottom
of wheel rim.
Car in normal loaded position on the ground. See Normal
loaded position.
Engine
control
module
Specified tires and wheels, correct tire pressure, even tire
wear
-'* 9-
.%A
Correct wheel bearing play
T'== ..t, 9 B
-.m
Model with air suspension (EHC): Disconnect electrical har-
ness connector to air supply pump to prevent automatic
height regulation.
When finished, reset ride height using BMW diagnostic
scan tools DIS or
MoDiC.
NOTE-
Airsupply pump is located beneath a cover under the spare
tire in the floor of the cargo compartment.
- If ride height is outside specification listed, install new
springs. Suspension spring removal and installation is cov-
ered in
310 Front Suspension and 330 Rear Suspension.
Normal loaded position
Each front seat 68 kg (150 Ib)
Center of rear seat 68 kg (150 lb)
Trunk 21 kg (46 lb)
Fuel tank full

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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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, Brake caliper bolt tool
4 ASC bleeder wrench
(Tool No. BMW 34
3 110)
4 Brake line flare wrench set (12 mm, 14 mm, 17 mm, 19 rnm)
(Tool No. BMW 34 3 150)
34 3 152
34 3 153
34 3 154
4 DSC Dressure sensor installation socltet
4 ABS IASC or ABSI DSC control unit 42-pin harness adapter
(break-out adapter)
(Tool No. BMW 34 5 240)
0
(Tool NO. BMW 34 5 160)

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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