Abs/traction Control - Service Information BMW M5 E60/E61

Dynamic Stability Control DSC 8

E60, E61, E63, E64

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Introduction

The BMW 5 Series and the BMW 6 Series are equipped with Dynamic Stability Control DSC 8 as standard. DSC 8 is a further development of DSC 5.7 familiar from the E65.

The DSC unit (comprising a DSC control unit and hydraulic unit) performs even better. System supplier of DSC 8 is Bosch.

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Introduction (Con't)

The principal new features of DSC 8 are

1. Very compact DSC unit, approximately 25 % smaller and some 30 % lighter
2. No electric pre-pressurising pump
3. DSC unit connected to the chassis CAN (F-CAN) in addition to connection to the powertrain CAN (PT-CAN)

DSC is a control system that maintains dynamic stability within the laws of physics when the car is being driven close to its limits of performance and handling.

It also improves traction.

The parameters DSC needs as input in order to discharge its control functions are as follows

1. Yaw rate (measure of movement of the car about its vertical axis)
2. Lateral acceleration
3. Wheel speeds (measure of the car's road speed)
4. Steering angle
5. Brake pressure

The measured values available are used to calculate how the car is moving at any given instant. This actual condition is compared to the nominal values calculated in the DSC control unit.

If the actual status deviates from the nominal values the DSC system goes active and intervenes in the braking system or the engine management system, as applicable.

The Advantages: The intervention of DSC in the engine control and brakes provides outstanding driving stability and traction in all driving situations. DSC combats negative, dynamic driving forces. This means DSC brings about maximum active safety within the physical limits. DSC thus enhances driving comfort by allowing more relaxed driving.

Brief description of components

Dynamic Stability Control (DSC) comprises the following components

DSC Unit

The DSC unit can be broken down into the components of DSC control unit and hydraulic unit.

The DSC control unit regulates the pressure in the brake system via the hydraulic unit (comprises valve block and pump motor).

Installation Location

The DSC unit is located in the engine compartment, in front of the right-hand suspension strut dome.

Exception E60, E61 with M57 TOP (with two turbochargers): For this version of the engine, the DSC unit is located in the front left of the engine compartment.

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The DSC unit consists of the DSC control unit and the hydraulic unit. The hydraulic unit comprises principally the valve block and the pump motor. The following components are integrated in the valve block

1. 2 pump elements driven by eccentric shafts (front-axle brake circuit and rear-axle brake circuit)
2. 2 intake valves, 2 switchover valves and 4 inlet valves and 4 outlet valves (12 solenoid valves)
3. Internal brake pressure sensor
4. 2 accumulators

The (design-related) separating line between the DSC control unit and the hydraulic unit runs through the solenoid valves. The electrical components of the solenoid valves (valve coils) are assigned to the DSC control unit and are directly connected to the board. The mechanical components of the valve (principally the valve domes with the tappets) are affixed to the hydraulic unit.

Pin Assignment

The DSC control unit is integrated into the vehicle electrical system via a 38-pin connector.

DSC UNIT PIN ASSIGNMENT X1746, 38-PIN

Pump Motor With Self-Drawing Return Pump

The return pump is integrated in the hydraulic unit. The return pump contains two pump elements (driven by eccentric shaft) that supply the front-axle brake circuit and rear-axle brake circuit. The return pump is driven by the pump motor. When ABS regulation is active, the brake pressure at the wheels is regulated by controlled build-up and reduction of pressure. When pressure is reduced in the wheel brakes, the brake fluid is fed back towards the tandem-brake master cylinder by the return pump. When automatic stability control is active, the pressure is also built up by the return pump. The direction of activity is determined by the switchover valves. The return pump draws in fluid from the expansion tank via the tandem-brake master cylinder.

Accumulators

The accumulators (1 for each brake circuit) take up the initial volume of brake fluid as pressure is reduced. This volume has to be taken up when ABS, ASC or DSC regulation is active, until the pump motor has fully started.

Inlet And Outlet Valves

The inlet and outlet valves (1 pair for each wheel brake) modulate the pressure in the wheel brakes during regulation.

Intake Valves (High-Pressure Switching Valves) And Switchover Valves

The intake valves (closed when no current is applied) and the switchover valves (open when no current is applied). One pair for each brake circuit-regulate the build-up of pressure during active DSC brake intervention.

Internal Brake Pressure Sensor

The brake pressure sensor measures the braking pressure applied by the brake pedal and the brake booster. The brake pressure sensor has a measuring range from 0 to 250 bar. Its zero point is continuously adjusted when the brake light switch is not activated and the ignition is switched ON.

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The DSC control unit regulates all DSC sub-functions.

Note. Additional function for vehicle with trailer module In the E60/E61 with trailer module, DSC also takes on the trailer stabilising control function (see SYSTEM FUNCTIONS ).

4 Wheel Speed Sensors

Each of the wheel speed sensors registers the speed of an individual wheel. In addition, the wheel speed sensors recognize the direction of rotation (forwards or backwards)

The 4 wheel speed sensors are each affixed to the respective wheel hub.

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The increment wheel assigned to the wheel speed sensor is integrated in the wheel bearing. The housing of the wheel speed sensor contains 3 Hall sensors (elements) adjacent to each other. The measuring procedure employing 3 Hall sensors allows the wheel speed sensor to recognise forwards and backwards travel.

How It Works

The signal is converted entirely within the wheel speed sensor. The signals from 2 of the Hall sensors (1 and 3) are used to generate a difference signal. The signal frequency and the air gap between the wheel speed sensor and increment wheel are derived from this difference signal. The time lag between the signal from the middle Hall sensor and the difference signal is used to identify forwards or backwards travel. The additional information about the air gap and the direction of rotation is given by the pulse width of the current pulse. When the vehicle is stationary, a current pulse is generated approximately every 740 milliseconds, contrasting with previous wheel speed sensors. This current pulse indicates the availability of the wheel speed sensor.

DSC Sensor

The DSC sensor measures the rotation of the vehicle around the vertical axis (yaw rate) and the lateral acceleration of the vehicle. A car fitted with Active Steering has two DSC sensors (redundancy). The DSC sensors are connected to the DSC and AS control units via the chassis CAN.

The standard DSC sensor is underneath the driver's seat. For reasons of safety on vehicles with Active Steering, a second DSC sensor is integrated along with the standard DSC sensor as a redundant sensor. The second DSC sensor is located underneath the front-passenger seat

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The DSC sensors are a combination of lateral acceleration sensor and yaw-rate sensor. The DSC sensor consists of

1. Housing cover
2. Board with electronic evaluation unit for converting signals
3. Sensor electronics: The sensor electronics consists of 2 piezoelectric acceleration sensors. A spring-mounted weight is hung in the measuring cell of the acceleration sensor.
4. Damper to prevent mechanical overstressing
5. Housing with connector

Technically, the two DSC sensors are virtually identical. DSC sensor 2 has an extra terminating resistor. The two DSC sensors have different part numbers. In addition, the DSC sensors make use of a different identifier in the CAN bus. This excludes the possibility of confusing the DSC sensors.

When the vehicle accelerates, the spring-mounted hanging weight is also accelerated. The force needed to achieve this is generated by mechanical tension in the piezoelectric material. This results in a shift in the electric charge. This charge shift is picked up by electrodes and processed as an electric signal. The yaw rate is derived from the difference between the two acceleration signals.

The second DSC sensor redundantly registers the signals for lateral acceleration and yaw rate. The fact that two DSC sensors are used means that plausibility can be monitored. The two DSC sensors are triggered (excited) by the DSC control unit every 10 milliseconds. Each time they are triggered, the two DSC sensors send their signals to the F-CAN.

Steering-Angle Sensor

The steering-angle sensor detects the movements of the steering wheel. The steering-angle sensor is part of the steering column switch cluster (SZL).

On vehicles with Active Steering, the cumulative steering angle is measured by the cumulative steering angle sensor (= steering angle at steering gear output).

The steering-angle sensor is integrated in the steering-column electronic circuitry. The steering-column electronic circuitry is part of the steering column switch cluster (SZL).

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Construction

The steering-angle sensor is a potentiometer with 2 sliding contacts offset by 90°. The use of 2 sliding contacts allows the direction of turn to be recognised.

DSC needs the steering angle for its regulation function. The steering angles detected by the sliding contacts (2 voltage values) make up a complete turn of the steering wheel. Once the steering wheel has been turned through 360°, the voltage values are repeated. The steering-angle sensor thus also counts the number of turns of the steering wheel.

The entire steering angle measured by the steering-angle sensor is made up of

1. Steering-angle sensor correction value: This correction value determines the straight-ahead position of the steering wheel. The correction value is defined and stored when the steering-angle sensor is calibrated.
2. Current measured steering angle
3. Number of turns of steering wheel

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The steering angle, including the number of turns of the steering wheel, must be available when the ignition is switched ON. For this reason, the steering column switch cluster (SZL), and with it the steering-angle sensor, has permanent current via terminal 30. This allows steering movements to be registered even when terminal R is switched OFF.

Open circuits would cause the number of turns of the steering wheel stored in the steering-angle sensor to be lost. To ensure that the steering-angle sensor remains functional even in the event of an open circuit, the DSC control unit "learns" the steering angle via a plausibility check (initialisation). The DSC control unit computes the steering angle from the wheel speeds on the front axle. The plausibility check compares these signals with those from other sensors to recognise whether the vehicle is operating with an incorrectly calibrated steering-angle sensor.

If initialisation is unsuccessful after starting up to a speed threshold of approx. 25 km/h, then the following happens

1. DSC is deactivated
2. The DSC warning light comes on
3. A fault entry is stored in the DSC control unit (not in the steering-angle sensor)

Note. Steering-angle sensor failure If the steering-angle sensor fails, ABS will remain active.

The DSC unit incorporates a brake pressure sensor. This brake pressure sensor registers the braking pressure applied by the brake pedal and the brake booster.

2 Additional Brake Pressure Sensors (Only In Combination With Active Cruise Control, ACC)

Two more brake pressure sensors are integrated, one in the front brake circuit and one in the rear brake circuit. A car fitted with Active Cruise Control (ACC) is slowed by DSC when necessary. The braking pressure applied in this way at the front and rear wheels is often very low. It is controlled by means of the brake pressure sensors (objective: to equalize the brake load at the front and rear axles on long downhill stretches).

2 Brake Pad Wear Sensors

The brake pad wear sensors (front left and rear right) monitor the thickness of the brake pads. The Condition Based Service indicator (CBS) in the instrument cluster lights up if brake pad wear progresses to the point at which it becomes critical.

Brake Light Switch

The brake light switch tells DSC when the brake pedal has been pressed.

Brake Fluid Level Switch

If the brake fluid level is too low, this will be detected and the DSC control unit will be informed.

An insufficient brake fluid level will be indicated on the instrument cluster by the general brake system warning light (signal via CAN bus).

DSC Button

The DSC button is in the center console switch cluster (SZM) The DSC button has three switching states

1. DSC ready for use
2. DTC ready for use
3. DSC completely switched off

Digital Motor Electronics Or Digital Diesel Electronics

Note. The DSC control unit also communicates with the following control units

The DME/DDE controls engine adaptation (for example, reduction in engine output to prevent spin at the driven wheels). The DME/DDE also receives the converted wheel speed signal from the rear right wheel. This signal is used to check the plausibility of engine misfires (DME).

Car Access System Or Multi-Audio System Controller/Car Communication Computer

The CAS control unit and M-ASK/CCC receive the converted wheel speed signal from the rear left wheel.

Both these control units use this signal to ascertain whether the car is moving or at a standstill.

Safety And Gateway Module

The SGM is the gateway between

1. PT-CAN
2. K-CAN
3. Byteflight
4. Diagnostic Wire

Active Cruise Control

DSC receives requests from the Active Cruise Control (ACC) via the PT-CAN. In response, DSC reduces speed by applying the brakes at all four wheels.

Light Module

As required by law, the brake lights are activated in the event of automatic braking when the Electronically Controlled Deceleration function (ECD) is triggered by the ACC. This function requires a signal sent via the K-CAN to the light module (LM).

Instrument Cluster

The DSC control unit actuates the indicator and warning lights for DSC in the instrument cluster.

Electronic gearbox control (vehicles with automatic transmission)

The transmission control (EGS) receives the wheel speed signals via the PT-CAN.

The gearbox controller responds by adapting the gearshift characteristics for cornering and ascents. In addition, the gearshift characteristics are adapted to winter conditions (high wheel slip).

Moreover, gearshifts are suppressed during DSC control.

Central Information Display and Controller

The detailed texts for the Check Control messages are shown in the Central Information Display (CID).

CID and controller are also used to initialize the tire defect indicator (RPA).

Telephone Control Unit With GPS Antenna

If the car is not fitted with a navigation system , the telephone control unit receives the converted wheel speed signals from the front left and right wheels.

The telephone control unit uses these signals to pinpoint the car's position as precisely as possible.

System functions

The dynamic stability control system (DSC) controls longitudinal and transverse dynamics by means of engine and brake system intervention.

Dynamic Stability Control (DSC) incorporates the following functions

1. Anti-lock brake system (ABS)
2. Electronic brake force distribution (EBV)
3. Cornering brake control (CBC)
4. Automatic stability control (ASC)
5. Dynamic traction control (DTC)
6. Electronic brake force distribution (MSR)
7. Dynamic brake control (DBC)
8. Electronically controlled deceleration (ECD only in conjunction with ACC)
9. Trailer stabilizing control (only in conjunction with trailer module for E60 and E61)

Note. Yaw-rate control by the Active Steering (AS) Active Steering also influences the vehicle's yaw characteristics. Consequently, the software in DSC is modified accordingly in cars fitted with Active Steering (for example, 2 DSC sensors).

Dynamic Stability Control

Dynamic Stability Control (DSC) detects the current status of the vehicle by evaluating the sensor signals. This status is compared with the nominal values derived from a computational model. In this way, the system recognizes incipient instabilities.

The vehicle is stabilized as soon as a deviation exceeds the control threshold stored in the DSC control unit. Stabilization (within the limits imposed by the laws of physics) is achieved by reducing engine power and by braking individual wheels.

DSC interventions override the ABS and ASC functions.

The DSC function can be deactivated by means of the DSC button.

Anti-Lock Braking System

The anti-lock braking system (ABS) stops the wheels locking during braking.

Advantage: Shorter stopping distances, the car retains its directional stability and remains steerable.

Brake pressure is regulated at all wheels to ensure that each wheel runs in the best possible slip range. When this happens, slip is controlled so that the maximum possible braking and lateral stability forces can be transmitted.

ABS alone is available for braking if a sensor for DSC fails or if a bus fault occurs (PT-CAN or chassis CAN). ABS is the surviving safety function in circumstances in which DSC control is no longer possible.

Electronic Brake Force Distribution

Electronic brake force distribution (EBV) is a component of the ABS. EBV regulates the brake force distribution between the front and rear axles, depending on vehicle load.

Advantage: Regardless of the load state of the vehicle, the best possible braking distance is achieved while driving stability is maintained.

If ABS fails, the EBV function is sustained for as long as possible.

The signals from at least two wheel speed sensors are needed for the EBV function.

Cornering Brake Control

Cornering Brake Control (CBC) is an extension of ABS. CBC increases driving stability when the brakes are applied as the car corners ("cornering logic").

Advantage: Optimum driving stability if brakes are partially applied when cornering.

The shift in wheel loads as the car corners (the onset of this phenomenon requires no more than light application of the brakes) can result in a reduction in handling stability. If required, CBC generates a stabilizing load moment when the brakes are applied lightly outside the ABS intervention range.

Automatic Stability Control

Automatic stability control (ASC) prevents the wheels spinning during acceleration by intervention in brake and engine operations.

Advantage: More traction and better driving stability.

If, for example, one of the wheels of the drive axle is on a high grip surface and the other is on a slippery surface, the wheel tending to spin is braked. If necessary, the engine's power output is also reduced.

Dynamic Traction Control

Dynamic traction control (DTC) offers better traction as a trade off against a reduction in stability in some circumstances. Consequently, its use should be reserved for exceptional conditions (driving in deep snow, for example).

The DTC function approximates to that of DSC with a slightly modified control strategy. DTC can be activated by deactivating DSC (DSC button). DTC intervenes in the braking actions to imitate the function of a conventional differential lock.

Advantage: Higher traction is available with DTC.

Vehicle stabilization intervention (e.g. reduced power output) is made slightly later than with DSC.

This enhances traction with a slight loss of driving stability. Occasionally, a compromise is needed between driving stability and traction.

This is especially true when accelerating and driving uphill on loose surfaces or in deep snow (= friction values demanding increased slip).

DTC allows DSC to provide a high degree of driving stability while retaining sufficient traction.

Engine Drag Torque Control

The engine drag torque control (MSR) counteracts the tendency of the wheels to lock on smooth surfaces. The engine's drag torque generated by downshifts or abrupt load changes can lock the driven wheels (especially on surfaces with a low coefficient of friction).

The wheel speed sensors tell MSR as soon as the wheels are about to lock. MSR then briefly reduces the engine's drag torque by opening the throttle slightly.

Advantage: The drive wheels retain their lateral stability in overrun mode.

Dynamic Brake Control

Dynamic brake control (DBC) assists the driver in emergency braking situations by automatically increasing the brake pressure.

Advantage: Shortest possible stopping distances in emergency braking situations, because the ABS control threshold is reached at all four wheels.

In emergency-braking situations, drivers often fail to apply sufficient force to the brake pedal. ABS regulation is then not activated.

In the following situations, the return pump increases the brake pressure until ABS regulation is activated

1. When the brake pedal is rapidly depressed with insufficient pedal pressure
2. When the brake pedal is depressed slowly and the demand for deceleration is subsequently high, after one wheel reaches the ABS control threshold.

Which wheel locks first depends on load and coefficient of friction of the road surface.

Example of a typical situation

The traffic slows, making light braking necessary at first, but then demands as short a stopping distance as possible.

Electronically Controlled Deceleration

The electronically controlled deceleration (ECD) reacts to a demand from the Active Cruise Control (ACC).

When ACC requires deceleration, DSC responds by applying the disc brakes on all four wheels (maximum rate of deceleration 2.5 m/s 2 ).

When the car is on a decent with the speed preset by the driver, ECD automatically applies the brakes in order to keep the car's speed constant at the preset value.

When the brakes are applied automatically in this way, the brake lights are activated in accordance with the requirements of road safety legislation. The light module does not activate the brake lights unless the vehicle's rate of deceleration is greater than 1m/s 2. This prevents the brake lights from flickering on and off.

Trailer Stabilizing Control (Only In Conjunction With Trailer Module For E60 And E61)

Trailer stabilizing control detects when a trailer is rocking about its vertical axis. The system functions at a speed of about 65 km/h when the trailer socket is in use.

With the aid of the DSC sensors, Dynamic Stability Control (DSC) monitors the vehicle's yaw behavior. If the trailer's rocking motion exceeds the limit, the engine output is reduced. In addition, DSC brakes all four wheels automatically.

If DSC is deactivated or faulty, then the trailer stabilizing control does not work either.

Tire Defect Indicator

The Run Flat Indicator (RPA) is not a function of the Dynamic Stability Control system.

RPA is integrated into the DSC control unit as the four wheel speed signals are required for this function.

By comparing the speed signals for all four wheels, the system detects differences in rolling circumference at the individual wheels. This enables the system to recognize a sudden loss of pressure in the tires.

Operation

The DSC button is in the center console switch cluster (SZM)

The DSC button has 2 functions that can be set by pressing the button for different lengths of time.

TIRE DEFECT INDICATOR FUNCTION

Note. Reactivating DSC Briefly pressing the button again reactivates the DSC function. The DSC indicator and warning light goes out (unless the system has developed a fault). If the DSC button remains pressed for longer than 10 seconds (e.g. by a handbag on the center console), DSC will detect an operating error. The DSC function remains active and cannot be deactivated until the ignition has been switched off and on again.

Switch-On Conditions

DSC is in ready mode after each engine start.

NOTES FOR SERVICE STAFF

Service staff should note the following points

1. General information: N/A
2. Diagnostics: N/A
3. Encoding/programming: Refer to «E60, E61, E63, E64: ENCODING/PROGRAMMING DSC 8»(/bmw/m5/e60e61-2004-2010/remont/anti-locktraction-control/#abstraction-control-service-information) .
4. Car & Key Memory: N/A

Subject to change.

Encoding The Steering-Angle Sensor

Automatic Encoding Of The DSC Control Unit

After replacing the DSC control unit, the DSC control unit is automatically encoded. If the vehicle identification number differs, the DSC control unit will obtain the necessary data (vehicle identification) from the vehicle order. The vehicle order is stored in the instrument cluster.

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The xDrive all-wheel drive system is also employed on the BMW 5-Series. These vehicles are equipped as standard with Dynamic Stability Control (DSC) 8Plus.

DSC 8Plus is an advanced development of DSC 8.

The DSC unit (comprising DSC control unit and hydraulic unit) is even more powerful. The newly developed switchover valves allow a more precise regulation, especially at low brake pressure. DSC 8Plus is supplied by Bosch.

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The principal new features of DSC 8Plus are

1. Additional functions: Brake Standby through precautionary pre-tensioning of the brakes in an emergency Brake disk drying on wet roads Detection of fading and increase in brake pressure during fading Soft stop when braking to standstill Start-off assistant
2. 2 additional brake pressure sensors, only in combination with Active Cruise Control (ACC)

Note. Option 203 not with option 217 The option "xDrive" can no longer be combined with the option "Active Steering" (installation space).

New From 09/2005

1. DSC 8Plus is also employed in the BMW 5-Series and 6-Series with rear-wheel drive (E60, E61, E63, E64). From this time on, the body gateway module (KGM) is the gateway to the PT-CAN.
2. DSC 8Plus is also employed on the BMW 3-Series with all-wheel drive (E90, E91). In these vehicles, the junction box electronics (JBE) is the gateway to the PT-CAN.

Note. New soft stop function not for BMW 3-Series all-wheel drive vehicles. For technical reasons, the soft stop function has not been incorporated on BMW 3-Series all-wheel drive vehicles

DSC is a control system that maintains dynamic stability within the laws of physics when the car is being driven close to its limits of performance and handling.

It also improves traction.

DSC needs the following input signals in order to discharge its control functions

1. Yaw Rate (Measure Of Movement Of The Car About Its Vertical Axis)
2. Lateral Acceleration
3. Wheel Speeds (Measure Of The Car's Road Speed)
4. Steering Angle
5. Brake Pressure

The measured values available are used to calculate how the car is moving at any given instant. The actual condition is compared with nominal values (values in stable driving conditions) that are calculated in the DSC control unit. If the actual condition differs from the nominal values, DSC is activated and initiates brake actions and/or engine control functions.

The advantages: The intervention of DSC in the engine control and brakes provides outstanding driving stability and traction in all driving situations.

DSC combats negative, dynamic driving forces. This means DSC brings about maximum active safety within the physical limits. DSC thus enhances driving comfort by allowing more relaxed driving.

The following components are described for the Dynamic Stability Control (DSC)

DSC Unit For DSC 8Plus: E60, E61, E63, E64

The DSC unit consists of the components DSC control unit and hydraulic unit.

The DSC control unit regulates the pressure in the brake system via the hydraulic unit (comprises valve block and pump motor).

E60, E61, E63, E64 The DSC unit is located in the engine compartment in front of the coolant expansion tank.

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E90, E91 The DSC unit is located under a cover at the front left on the bulkhead.

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The DSC unit consists of the DSC control unit and the hydraulic unit. The hydraulic unit comprises principally the valve block and the pump motor.

The following components are integrated in the valve block

1. 2 pump elements driven by eccentric shafts (front-axle brake circuit and rear-axle brake circuit)
2. 2 intake valves, 2 switchover valves and 4 inlet valves and 4 outlet valves (12 solenoid valves)
3. Internal brake pressure sensor
4. 2 accumulators

The (design-related) separating line between the DSC control unit and the hydraulic unit runs through the solenoid valves. The electrical components of the solenoid valves (valve coils) are assigned to the DSC control unit and are directly connected to the board. The mechanical components of the valve (principally the valve domes with the tappets) are affixed to the hydraulic unit.

The DSC control unit is integrated into the vehicle electrical system via a 38-pin connector.

DSC UNIT (DSC PLUS8) PIN ASSIGNMENT X1746, 38-PIN

The so-called return pump is integrated in the hydraulic unit. The return pump contains two pump elements (driven by eccentric shaft) that supply the front-axle brake circuit and rear-axle brake circuit. The return pump is driven by the pump motor. When ABS regulation is active, the brake pressure at the wheels is regulated by controlled build-up and reduction of pressure. When pressure is reduced in the wheel brakes, the brake fluid is fed back towards the tandem-brake master cylinder by the return pump (hence the term "return pump").

When automatic stability control is active, the pressure is also built up by the return pump. The direction of activity is determined by the switchover valves. The return pump draws in fluid from the expansion tank via the tandem-brake master cylinder.

The accumulators (1 for each brake circuit) act as initial volume stores for brake fluid as pressure is reduced. These volume accumulators are needed during ABS, ASC and DSC regulation, until the pump motor is running fully (compensation for volume change).

The inlet and outlet valves (1 pair for each wheel brake) modulate the pressure in the wheel brakes during regulation, regardless of brake pedal pressure.

The intake valves are closed when no current is applies, the switchover valves are open when no current is applied (1 pair for each brake circuit). These valves control the pressure build-up during active brake application by DSC by changing the direction of effect.

The brake pressure sensor measures the braking pressure applied by the brake pedal and the brake booster. The brake pressure sensor has a measuring range from 0 to 250 bar. The zero point is continuously adjusted when the brake light switch is not activated and the ignition is switched ON.

The active wheel speed sensors register the speed of an individual wheel at their circumference. Moreover, the wheel-speed sensors also recognize the direction of rotation (forwards or backwards).

When a wheel is stationary, the wheel-speed sensor emits a pulse every 0.75 seconds.

An active wheel-speed sensor is fitted to each wheel. On the front axle there is sensor gear opposite the wheel-speed sensor.

On the rear axle there is a ring of magnets around the wheel bearing (increment wheel). The north and south poles of the increment wheel alternate. One north pole with one south pole constitutes one increment (cf. tooth/gap on a sensor gear).

The wheel-speed sensor consists of 3 Hall sensors and an electronic evaluation unit.

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The complete signal processing takes place in the active wheel-speed sensors.

For example, the wheel-speed sensor on the rear axle: The active wheel-speed sensors change their electrical resistance when influenced by a magnetic field. Each increment generates 2 pulses in the wheel-speed sensor (96 pulses/revolution of wheel). For the data transmission to the control unit, additional data are added alongside the pulse. Functionally, this integrated data processing goes beyond the simple recording of speed of rotation.

The following additional information is possible, e.g.

1. Direction Of Rotation Of Wheel
2. Air Gap
3. Vehicle Standstill

In contrast to earlier wheel-speed sensors, a current pulse is transmitted approximately every 0.75 seconds when the vehicle is stationary. This current pulse indicates the availability of the wheel speed sensor.

The active wheel-speed sensors give the following benefits

1. Fast and reliable recognition of direction of travel
2. Improved actuation of transmission control
3. Improved actuation of navigation system

The DSC sensor measures

1. Vehicle rotation around the vertical axis (rate of yaw)
2. Lateral acceleration of vehicle
3. Longitudinal acceleration of vehicle

The DSC sensor is linked to the DSC control unit by the F-CAN.

E60, E61, E63, E64 The DSC sensor is located under the front-passenger seat on the floor assembly.

E90, E91 The DSC sensor is located on the seat cross member under the driver's seat.

A new feature for the DSC sensor is: The DSC sensor has an additional longitudinal-acceleration sensor. The DSC sensor still has a lateral-acceleration sensor and rotating-speed sensor.

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Within the micromechanical rotation-speed sensor there are 2 oscillating measuring devices that are guided by a retaining spring. An alternating current is sent through the conductor on the measuring device. The alternating current excites the measuring devices to constant oscillations with the magnetic field of the permanent magnet (natural frequency). Each measuring device has an acceleration sensor. The acceleration sensor measures the acceleration vertical to the oscillations. This measured acceleration is proportional to the yaw rate.

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Within the lateral-acceleration sensor there is a comb-like element that acts as a buffering mass. On both sides of this mobile element there are comb-like electrodes. This arrangement corresponds to a series connection of 2 capacitors. An alternating current is applied to give the two capacitors a phase alignment of 180°. When the vehicle accelerates laterally, the mobile mass is moved. The capacity of the capacitor changes with the distance between electrodes. The sensor signal thus generated corresponds to the lateral acceleration of the vehicle. A longitudinal-acceleration sensor works in the same way as a lateral-acceleration sensor. The arrangement is turned through 90°.

The steering-angle sensor detects the movements of the steering wheel. The steering angle sensor is part of the steering column switch cluster (SZL). The steering column switch cluster is connected to the Chassis CAN.

The DSC unit incorporates a brake pressure sensor. This brake pressure sensor registers the braking pressure applied by the brake pedal and the brake booster.

The brake pad wear sensors (front left and rear right in the inner brake pads) provide additional information about the thickness of the brake pads. This additional information (2 reference points) is compared to the value calculated by the DSC.

A critical brake lining thickness will be indicated in the instrument cluster by the Next Service indicator (Condition Based Service, CBS) and by the general brake warning lamp lighting up red.

The brake light switch tells DSC when the brake pedal has been pressed.

Insufficient brake fluid is detected and a signal sent to the DSC control unit.

If there is insufficient brake fluid, this will be indicated in the instrument cluster by the general brake warning lamp lighting up red.

DTC Button

The DTC button is in the center console switch cluster (SZM) The signal is transmitted on the K-CAN and via a separate wire. The DTC button has the letters "DTC".

The DTC button has 3 switching states

1. DSC ready for use
2. DTC ready for use
3. DSC completely switched off

E60, E61, E63, E64 The DTC button is in the centre console switch cluster (SZM) The signal is transmitted on the K-CAN and via a separate wire. The signal on the separate wire is decisive.

E90, E91 The DTC button is connected to the junction box electronics (JBE). The JBE transmits a bus signal.

DME or DDE: digital engine electronics or digital diesel electronics

Note. The DSC control unit also communicates with the following control units

The DME/DDE controls engine adaptation (for example, reduction in engine output to prevent spin at the driven wheels). The DME or DDE also receives the converted wheel speed signal from the rear right wheel. This signal is used to check the plausibility of engine misfires (DME). The signal on the PT-CAN is redundant.

RLS: Rain-Light Sensor

The signal from the rain-light sensor is used to brake the brake disks dry on a wet road surface. In addition, it is important for a wiper stage to be switched on.

The rain-light sensor supplies the signal on the CAN bus.

E90, E91 The rain-light sensor is connected to the roof control panel (FZD) via the LIN bus.

CAS and M-ASK/CCC: Car Access System And Multi-Audio System Controller/Car Communication Computer

The CAS control unit and M-ASK/CCC receive the converted wheel speed signal from the rear left wheel.

Both these control units use this signal to ascertain whether the car is moving or at a standstill.

SGM: Safety And Gateway Module

E60, E61, E63, E64 up to 09/2005 The SGM is the gateway between

1. PT-CAN
2. K-CAN
3. Byteflight
4. Diagnosis cable to OBD socket

E60, E61, E63, E64 from 09/2005 The body gateway module (KGM) is the gateway. The door modules and byteflight are discontinued.

JBE: Junction Box Electronics

E90, E91 from 09/2005 The JBE is the gateway between

1. PT-CAN
2. K-CAN
3. Byteflight
4. Diagnosis cable to OBD socket

ACC: Active Cruise Control

DSC receives requests from the Active Cruise Control (ACC) via the PT-CAN. In response, DSC reduces speed by applying the brakes at all four wheels.

E90, E91 from 09/2005 The request for brake application is given by the LDM control unit (LDM: longitudinal dynamics management).

LM: Light Module

As required by law, the brake lights are activated in the event of automatic braking when the Electronically Controlled Deceleration function (ECD) is triggered by the ACC.

This function requires a signal sent via the K-CAN to the light module (LM).

KOMBI: Instrument Cluster

The DSC control unit actuates the indicator and warning lights for the individual DSC functions via the instrument cluster (signal via CAN bus).

EGS: Electronic Gearbox Control (Vehicles With Automatic Transmission)

The transmission control (EGS) receives the wheel speed signals via the PT-CAN.

The gearbox control responds by adapting the gearshift characteristics for cornering and ascents. In addition, the gearshift characteristics are adapted to winter conditions (high wheel slip).

Moreover, gearshifts are suppressed during DSC control.

CID and CON: Central Information Display And Controller

The detailed texts for the Check Control messages are shown in the Central Information Display (CID).

CID and controller are also used to initialize the tire defect indicator (RPA).

With xDrive an additional function can be activated to reduce speed when driving downhill: Hill Descent Control (HDC)

TCU or ULF: Telephone Control Unit With GPS Antenna

If the car is not fitted with a navigation system , the telephone control unit receives the converted wheel speed signals from the front left and right wheels.

The telephone control unit uses these signals to pinpoint the car's position as precisely as possible.

The Dynamic Stability Control system (DSC) controls longitudinal and lateral dynamics by means of engine and brake system intervention.

DSC 8Plus includes the following new functions

1. Brake Standby through pre-tensioning of the brakes in an emergency
2. Brake disk drying on wet roads
3. Fading compensation
4. Soft stop when braking to standstill
5. Start-off assistant

DSC 8Plus includes the following familiar functions

1. ABS: Anti-lock braking system
2. EBV: Electronic brake force distribution
3. CBC: Cornering brake control
4. ASC: Automatic stability control
5. DTC: Dynamic traction control
6. MSR: Engine drag torque control
7. DBC: Dynamic brake control
8. HDC: Hill Descent Control
9. ECD: Electronically controlled deceleration (only in conjunction with ACC)
10. Trailer stabilization control
11. All-wheel control
12. RPA: Run Flat Indicator
13. CBS: Condition Based Service

Brake Standby Through Pre-Tensioning Of The Brakes In An Emergency

Pre-tensioning the brakes shortens the brakes' response time.

If the accelerator pedal is rapidly released (accelerator pedal angle), the brakes are immediately pre-tensioned. DSC generates a low brake pressure without a measurable deceleration taking place. The clearance between the brake pads and brake disks is eliminated. If the brakes are not applied within half a second, this precautionary brake pressure is cancelled. The pre-tensioning of the brake pads is active at road speeds greater than 70 km/h.

Brake Disk Drying On Wet Roads

Braking dry removes moisture that gathers on the brake disks during journeys on wet roads or in rain. The brake pads are lightly applied. This function also shortens the brakes' response time.

Depending on the signal from the rain sensor and the position of the wiper switch, DSC cyclically generates a low brake pressure. This creates no measurable deceleration on the vehicle. The brake pads are cyclically applied. This means that the brake disk are regularly wiped down. How often and how long the brake pads are applied depends on

1. The intensity of the rain, e.g. the speed of the windscreen wiper
2. Road speed greater than 70 km/h

Fading Compensation

Fading means: braking effect deteriorates as a result of high brake disc temperatures.

If fading is detected, DSC reacts by increasing the brake pressure above that specified by the driver.

At very high brake disc temperatures, fading compensation is indicated by the following

1. General brake warning lamp lighting up yellow
2. Check Control symbol in LCD display in instrument cluster lighting up yellow

DSC detects fading as follows: DSC compares the current vehicle deceleration with a nominal value based on the current brake pressure.

DSC increases brake pressure until the nominal deceleration is achieved or until all wheels are subject to ABS control. The process is ended when the brake pedal is no longer depressed or when the speed drops below a certain threshold.

Soft Stop When Braking To Standstill

Soft stop prevents the vehicle from jolting to a stop (e.g. if the driver is inexperienced).

When the vehicle is braked to a standstill, there is no uncomfortable jerk (causing the occupants to "lurch" forward). DSC calculates the moment that standstill can be expected from the current road speed and deceleration. Just before standstill is achieved, the brake pressure on the rear axle is reduced so that the vehicle stops with practically no jerking. Soft stop is only active for light braking, so that the shortest possible stopping distance can still be achieved in emergency braking situations.

Start-Off Assistant

When pulling away on a slope, it is necessary to move your foot from the brake pedal to the accelerator pedal. The start-off assistant prevents the vehicle from rolling downhill in the following situations

1. Uphill In Forward Gear
2. Uphill In Reverse Gear

It does this by maintaining the brake pressure needed to hold the vehicle. The gradient is recorded by the longitudinal-acceleration sensor in the DSC control unit. The braking torque and engine torque needed is calculated from the gradient. When pulling away is detected, brake pressure is reduced as soon as the available engine torque is sufficient to move the vehicle in the direction required. The start-off assistant is deactivated when the parking brake is applied. If no move is made to pull away within 2 seconds of the brake pedal being released, the start-off assistant will be deactivated.

DSC: Dynamic Stability Control

Dynamic Stability Control (DSC) detects the current status of the vehicle by evaluating the sensor signals.

This status is compared with the nominal values derived from a computational model.

In this way, the system recognizes incipient instabilities.

The vehicle is stabilized as soon as a deviation exceeds the control threshold stored in the DSC control unit. Stabilization (within the limits imposed by the laws of physics) is achieved by reducing engine power and by braking individual wheels.

DSC interventions override the ABS and ASC functions.

The DSC function can be deactivated by means of the DTC button.

ABS: Anti-Lock Braking System

The anti-lock braking system (ABS) stops the wheels locking during braking.

Advantage: Shorter stopping distances, the car retains its directional stability and remains steerable.

Brake pressure is regulated at all wheels to ensure that each wheel runs in the best possible slip range.

When this happens, slip is controlled so that the maximum possible braking and lateral stability forces can be transmitted.

ABS alone is available for braking if a sensor for DSC fails or if a bus fault occurs (PT-CAN or chassis CAN).

ABS is the surviving safety function in circumstances in which DSC control is no longer possible.

EBV: Electronic Brake Force Distribution

Electronic brake force distribution (EBV) is a component of the ABS. EBV regulates the brake force distribution between the front and rear axles, depending on vehicle load.

Advantage: Regardless of the load state of the vehicle, the best possible braking distance is achieved while driving stability is maintained. The brake pads wear more evenly.

If ABS fails, the EBV function is sustained for as long as possible.

The signals from at least two wheel speed sensors are needed for the EBV function.

CBC: Cornering Brake Control

Cornering Brake Control (CBC) is an extension of ABS. CBC increases driving stability when the brakes are applied as the car corners ("cornering logic").

Advantage: Optimum driving stability if brakes are partially applied when cornering.

The shift in wheel loads as the car corners (the onset of this phenomenon requires no more than light application of the brakes) can result in a reduction in handling stability. If required, CBC generates a stabilizing load moment when the brakes are applied lightly outside the ABS intervention range.

ASC: Automatic Stability Control

Automatic stability control (ASC) prevents the wheels spinning during acceleration by intervention in brake and engine operations.

Advantage: More traction and better driving stability.

If the wheels on the driven axle have a different level of grip, the wheel that tends to spin is braked. If necessary, the engine's power output is also reduced.

DTC: Dynamic Traction Control

DTC is a variation of DSC that has been optimized for forward momentum in certain road conditions.

Dynamic traction control (DTC) offers better traction as a trade off against a reduction in stability in some circumstances. Consequently, its use should be reserved for exceptional conditions. It is advisable to briefly activate DTC in the following exceptional circumstances

1. To rock the vehicle free or to pull away in deep snow or on a loose surface.
2. When driving on snowy uphill stretches, in slush and on roads that have not been
3. When driving with snow chains.

The DTC function approximates to that of DSC with a slightly modified control strategy.

DTC can be activated by deactivating DSC (DTC button). DTC intervenes in the braking actions to imitate the function of a conventional differential lock. This effect of this is to increase the input torque on those wheels that are on a higher-friction surface.

Advantage: Higher traction is available with DTC.

Vehicle stabilization intervention (e.g. reduced power output) is made slightly later than with DSC. In certain situation, the driver has to intervene more intensively himself to stabiles the vehicle.

MSR: Engine Drag Torque Control

The engine drag torque control (MSR) counteracts the tendency of the wheels to lock on smooth surfaces. The engine's drag torque generated by downshifts or abrupt load changes can lock the driven wheels (especially on surfaces with a low coefficient of friction).

The wheel speed sensors tell MSR as soon as the wheels are about to lock. MSR then briefly reduces the engine's drag torque by opening the throttle slightly.

Advantage: The drive wheels retain their lateral stability in overrun mode.

DBC: Dynamic Brake Control

Dynamic brake control (DBC) assists in emergency braking situations by automatically increasing the brake pressure.

Advantage: Shortest possible braking distances in emergency braking situations by achieving ABS regulation on all four wheels.

The brake pedal is frequently not depressed strongly enough in emergency braking situations. ABS regulation is then not activated.

In the following situations, the return pump increases the brake pressure until ABS regulation is activated

1. When the brake pedal is rapidly depressed with insufficient pedal pressure
2. When the brake pedal is depressed slowly and the demand for deceleration is subsequently high, after one wheel reaches the ABS control threshold.

Which wheel locks first depends on load and coefficient of friction of the road surface.

Example of a typical situation

The traffic slows, making light braking necessary at first, but then demands as short a stopping distance as possible.

HDC: Hill Descent Control

Hill Descent Control (HDC) is an automatic cruise control system on all-wheel-drive vehicles for driving downhill. HDC can be switched on and off at the Central Information Display (CID): "Settings" menu and "Vehicle settings" sub-menu.

HDC automatically reduces the vehicle's speed. The brakes are applied on all four wheels to reduce road speed to just above walking pace. This allows stable downhill driving on steep and slippery surfaces.

HDC holds this speed constant (all DSC functions remain active). The vehicle's road speed can be continuously varied within the specified values by depressing the accelerator pedal and brake pedal or the cruise control system steering column stalk.

At the factory, HDC is assigned to the lower freely programmable button on the multi-function steering wheel.

The electronically controlled deceleration (ECD) reacts to a demand from the Active Cruise Control (ACC).

When ACC requires deceleration, DSC responds by applying the disc brakes on all four wheels (maximum rate of deceleration 2.5 m/s 2).

When the car is on a decent with the speed preset by the driver, ECD automatically applies the brakes in order to keep the car's speed constant at the preset value.

When the brakes are applied automatically in this way, the brake lights are activated in accordance with the requirements of road safety legislation.

The light module does not activate the brake lights unless the vehicle's rate of deceleration is greater than 1m/s2. This prevents the brake lights from flickering on and off.

Trailer Stabilization Control

Trailer stabilizing control detects when a trailer is rocking about its vertical axis. The system functions at a speed of about 65 km/h when the trailer socket is in use.

With the aid of the DSC sensors, Dynamic Stability Control (DSC) monitors the vehicle's yaw behavior. If the trailer's rocking motion exceeds the limit, the engine output is reduced. In addition, DSC brakes all four wheels automatically.

If DSC is deactivated or faulty, then the trailer stabilizing control does not work either.

All-Wheel Control

Dynamic Stability Control (DSC) specifies the nominal value for xDrive all-wheel control. The DSC control unit calculates the locking moment for the multi-plate clutch in the transfer box.

The nominal value depends on the vehicle's tendency to oversteer or understeer and wheelslip. The nominal value is sent via the PT-CAN to the VTG control unit.

The VTG control unit reports the actual set locking moment back to the DSC control unit.

The DSC control unit calculates the locking torque for the multi-plate clutch as follows

1. Pre-activation = driver's command
2. Driving dynamic control
3. Detection of different tire rolling circumferences

RPA: Run Flat Indicator

The Run Flat Indicator (RPA) is not a dynamic driving control function.

RPA is integrated into the DSC control unit as 4 wheel speed signals are needed for this function.

By comparing the speed signals for all four wheels, the system detects differences in rolling circumference at the individual wheels. This enables the system to recognize a gradual loss of pressure in the tires.

CBS: Condition Based Service

CBS is not a driving dynamic function.

Condition Based Service, as the name suggests, is a means of ensuring that the car is serviced as and when necessary. CBS comprises various maintenance operations, e.g. engine oil, spark plugs and brake pads.

The remaining distance for the front and back brake pads are calculated separately in the DSC control unit.

When making the calculation, the condition of the brake pad wear sensors is taken into account (reference point at 6 mm and 4 mm).

E60, E61, E63, E64 The DTC button is in the center console switch cluster (SZM).

E90, E91 The DTC button is located between the central air vents in the instrument panel.

The DTC button has 2 functions that can be set by pressing the button for different lengths of time.

DTC BUTTON FUNCTIONS

Note. Reactivating DSC Briefly pressing the button again reactivates the DSC function. The DSC indicator and warning light goes out (unless the system has developed a fault). If the DTC button remains pressed for longer than 10 seconds (e.g. by a handbag on the center console), DSC will detect an operating error. The DSC function remains active and cannot be deactivated until the ignition has been switched off and on again.

PRECONDITIONS FOR ACTIVATION

DSC is in ready mode after each engine start.

The following information is available for service staff

1. General information: Refer to «GENERAL INFORMATION ON DSC 8PLUS: E60, E61, E63, E64; E90, E91»(/bmw/m5/e60e61-2004-2010/remont/anti-locktraction-control/#abstraction-control-service-information) .
2. Diagnosis: Refer to «DSC 8PLUS DIAGNOSIS: E60, E61, E63, E64, E90, E91»(/bmw/m5/e60e61-2004-2010/remont/anti-locktraction-control/#abstraction-control-service-information__dsc-8plus-diagnosis-e60-e61-e63) .
3. Encoding/programming: Refer to «ENCODING/PROGRAMMING DSC 8PLUS: E60, E61, E63, E64, E90, E91»(/bmw/m5/e60e61-2004-2010/remont/anti-locktraction-control/#abstraction-control-service-information) .

Subject to change.

Calibrating The Steering-Angle Sensor

E60, E61, E63, E64 Calibration must be performed after the following operations

1. Exchanging the steering column switch cluster (SZL)
2. Programming the steering column switch cluster (SZL)
3. Work on the front-axle or steering
4. Adjusting work on the steering geometry

E90, E91 (all-wheel drive) Calibration must be performed in addition after the following operations

1. Replacement of DSC control unit NOTE: SZL is connected to the DSC control unit.

During calibration, the steering-wheel position set is stored in the steering-angle sensor as the straight-ahead position. For this reason, the steering wheel must be precisely in the straight-ahead position when the front wheels are calibrated. Calibration must be performed with the BMW diagnosis system.

The SZL is permanently supplied with voltage via terminal 30. This allows steering wheel movements for be detected even when the ignition is OFF. The neutral position of the steering wheel remains stored even after a power interruption. However, the current number of steering-wheel turns will be lost. The current steering-wheel turn is calculated again during a journey from the two front-wheel speeds. If this process has not been completed when a speed of approx. 25 km/h has been reached, the DSC indicator and warning light will light up.

All-Wheel Drive Vehicles The DSC indicator and warning light is immediately switched on in the event of a power interruption. The DSC indicator and warning light is switched off when the midrange setting of the steering angle is found at speeds up to 25 km/h.

The number of current steering-wheel turns can also be calculated as follows after a power interruption

1. Turn the steering wheel from stop to stop NOTE: Note different vehicle identification numbers It is not possible to calibrate the steering-angle sensor if the vehicle identification number stored in the steering column switch cluster differs from that stored in the CAS control unit

The vehicle identification number will be different if a used part is installed.

E90, E91 (All-Wheel Drive) The vehicle identification number is not transferred to the steering angle sensor. A replacement steering angle sensor is recognised by the changed serial number. When the steering angle sensor is calibrated, the new serial number will be stored in the DSC control unit.

Run Flat Indicator Initialisation

The customer is able to perform initialisation himself

1. With the on-board computer function in the instrument cluster on vehicles without iDrive (please refer to Owner's Handbook).
2. In the "Vehicle settings" menu on vehicles with iDrive (please refer to Owner's Handbook).

DSC 8Plus Diagnosis: E60, E61, E63, E64, E90, E91

Please note the following information for diagnosis on the DSC 8Plus

Clear The Fault Memory

If the fault memory cannot be cleared after a repair, proceed in the following order

1. Rectify the fault with the ignition OFF
2. Switch the ignition ON and then clear the fault memory
3. Switch the ignition OFF
4. Wait 5 to 10 seconds and then switch the ignition ON again
5. Clear the fault memory again NOTE: Indicator and warning lights stay lit. With certain faults, it is possible that the indicator and warning lights only go out after a short test drive.

Replacement of DSC Unit Or DSC Control Unit

Perform the following service functions/operations in the following order

1. Service function "Steering angle sensor calibration"
2. Service function "DSC unit bleed routine"
3. Service function "brake line interchange check"
4. Initialise Run Flat Indicator

Replacement Of DSC Sensor

After the DSC sensor has been replaced, the service function "DSC sensor calibration" must be performed. Here, the longitudinal-acceleration sensor in the DSC sensor is calibrated. The vehicle must be standing on a level surface when this is done. Moreover, the learned compensation values for yaw rate and lateral acceleration are cleared in the Active Steering control unit.

E60, E61, E63, E64

It is not necessary to encode the steering angle sensor. The steering angle sensor is automatically encoded when the steering column switch cluster is encoded (component in SZL).

E90, E91 (All-Wheel Drive)

When the DSC control unit is encoded, SZL encoding data is also stored in the DSC control unit. The DSC control unit will then transmit these data to the SZL through the F-CAN.

It is only possible to calibrate the steering angle sensor with the BMW diagnosis system after encoding.

Note. Note different vehicle identification numbers.

It is not possible to calibrate the steering-angle sensor if the vehicle identification number stored in the steering column switch cluster differs from that stored in the CAS control unit. The vehicle identification number will be different if a used part is installed.

E90, E91 (All-Wheel Drive) The vehicle identification number is not transferred to the steering angle sensor. A replacement steering angle sensor is recognised by the changed serial number. When the steering angle sensor is calibrated, the new serial number will be stored in the DSC control unit.

After replacing the DSC control unit, the DSC control unit will automatically encode itself up to the Run Flat Indicator. If the vehicle identification number differs, the DSC control unit will obtain the necessary data (vehicle identification) from the vehicle order. The vehicle order is stored in the instrument cluster.

Replacement of DSC Control Unit

To encode the Run Flat Indicator, the DSC control unit must be encoded after it has been replaced.

Proceed as follows after replacing the DSC control unit

1. Encoding DSC (because of Run Flat Indicator)
2. Calibrate steering angle sensor (service function)
3. Calibrate DSC sensor (service function)
4. Initialise RPA

On the basis of this recommendation and various other input variables, the light module decides whether main beam should be switched on or off.

See also:
• SYSTEM FUNCTIONS
• E60, E61, E63, E64: ENCODING/PROGRAMMING DSC 8
• DSC 8PLUS DIAGNOSIS: E60, E61, E63, E64, E90, E91