warning BMW X5 2002 E53 DSC System Workshop Manual

TABLE OF CONTENTS
Subject Page
Dynamic Stability Control (DSC III) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2
Corner Braking Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Electronic Brake Proportioning (EBV) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
Dynamic Braking System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
DSC New Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12
DSC New Feature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
Control Module Hydraulic Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
Rotation Rate/Transverse Acceleration Sensor . . . . . . . . . . . . . . . . . . . . . . . .19
Brake Pressure Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
DSC III Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
Steering Angle Sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
Brake Fluid Level Warning Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23
Diagnosis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24

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DSC - NEW FEATURE
TRACTION CONTROL
The traction control feature of the DSC III on the X5 cannot be switched OFF with the DSC
switch. Pressing the button will only switch off the dynamic stability control function of the
DSC.
The traction control feature is needed at all times to provide anti-spin control especially
when driving the vehicle off road. The DSC warning lamp in the instrument cluster will still
come on when the system is switched off manually or there is a fault in the system.
Off road traction control or HDC regulation places an additional load on the brakes. To pre-
vent overheating of the brakes and rotors, the temperature of the rotors is calculated over
time from the road speed and amount of brake application. If the temperature of one or
more rotors goes above 600o
C, the traction control or HDC function for that wheel will be
cancelled temporarily. Once the temperature of the rotor goes below 500o
C, the traction
application will be re-activated.
The normal braking function (including ABS) is always active at any temperatures.
DSC - NEW FEATURE
OFF-ROAD ABS Control Module Programming
The programming for ABS regulation have changed to allow a higher threshold for ABS reg-
ulation when driving off-road in loose gravel or dirt. A locked wheel is more effective in slow-
ing or stopping the vehicle because of the wedge that is built up in front of the tire.
The programming in the DSC control module allows one or both front wheel(s) to lock up
to a speed of 12 MPH as long as the vehicle is traveling straight ahead. If the DSC control
module receives a signal from the steering angle sensor indicating a turn, ABS regulation
will activate to prevent the lock and allow the vehicle to be steered.

BRAKE FLUID LEVEL WARNING SWITCH
A new fluid level switch is incorporated into the reservoir cap.
• With sufficient fluid level the reed contact is closed.
• When level drops below allowable limits, switch opens.
Since the normal position is closed, this circuit is monitored
for shorts to + and ground.
The LCM constantly monitors the input. If the ground signal is momentary,the LCM sig-
nals the Instrument cluster of the condition. The instrument cluster then informs the DSC
III control module over the CAN bus. If the signal is received just prior to the activation of
the charge pump, the charge pump activation is delayed.
If the signal is present for more then 25 seconds, the LCM issues two I BUS message for
the Instrument Cluster:
1. Post “Brake Fluid Level” in the Matrix display
2. Notify the DSC III via CAN that the Fluid level has been low for more than 25 seconds.
The DSC III control module immediately switches DSC III functions off and continuously illu-
minates the DSC indicator in the cluster.
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DIAGNOSIS
Diagnosis and troubleshooting of the DSC III system is carried out using the DIS Tester or
MoDiC. The DSC control module performs a self check every time the ignition is switched
on. The warning lamps for DSC and ABS will remain on during the self check.
Any faults with the system will cause the lamps to remain on when the engine is started.
Faults that only effect the DSC operation will cause the DSC warning lamp to remain on,
however ABS can still function.
If the battery has been disconnected, the DSC warning lamp will remain on until the vehi-
cle receives road speed signals front the front wheel speed sensors and the steering angle
sensor can calculate the direction of travel.