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E65 Voltage Supply and Bus Systems


Contents

Page

CHAP 1 E65 Voltage Supply and Bus SystemsIntroduction

Voltage supply - General - Positive supply line - Battery - Fuses Power module - General - System overview - Components - Inputs - Outputs connected to electronic battery master switch - Outputs not connected to electronic battery master switch - Functions - Diagnosis - Notes for Service

Electrical system General Bus systems - E65 bus system - E65 sub-bus systems Gateway - General - Method of operation

1 1

2 2 3 4 4 5 5 7 14 15

17

17 19 26 27

28 28 29 31 37 38 38 38

CHAP 2

CHAP 3


CHAP 4 Optical waveguides- General - Structure of plastic optical waveguides (LWL) - Colour coding of optical waveguides - Data transmission function by means of light impulses - Structure of MOST bus - Functional description of MOST Structure of byteflight - Functional description of byteflight - Attenuation of light impulses - Faults and their causes - Service/Diagnosis

Diagnosis bus General

40 40 41 42

43 44 45 47 49 50 51 57

58 58

CHAP 5



Introduction

With the engineering design of the E65, a variety of innovationshave been implemented for the vehicle electrical system.

The many control units have been distributed to several bussystems. New bus systems have also been used, and these allow a significantly greater data transfer speed.

The new systems K-CAN SYSTEM and K-CAN PERIPHERIE,with a data transfer rate of 100 KBd, replace the instrument, body and peripheral bus systems.

Two new bus systems have been implemented on the basis ofoptical waveguides (fibre-optic cables): the MOST bus and the byteflight. The MOST bus connects the audio components to one another. The byteflight connects the components respon- sible for passive safety in the vehicle.

For the first time, a power module is used to control the voltagesupply of the general vehicle electrics.

The diagnostic concept "BMW fast" (BMW fast access forservice and testing) now applies for diagnosis.

-1-


Voltage supply

- General

The voltage supply for the general electrical system is controlledby the power module.

The fuses in the engine compartment, the alternator and thestarter motor are connected directly to the battery.

KT-8366

Fig. 1: Electrical voltage supply via the power module

-2-


- Positive supply line

In the E65, a ribbon cable made of aluminium (120 mm2) is beingused for the first time.

It is routed through the vehicle interior from the boot to the frontbulkhead.

KT-7951

Fig. 2: 120 mm2 ribbon cable for positive power lead in the E65

-3-


- Battery

The E65 is fitted with a standard battery (12 V/110 Ah) with"Magic Eye".

- Fuses

The locations of the fuses are as follows:

- Luggage compartment Equipment mounting bracket, rear right

Junction point with 120 mm2 aluminium ribbon cable

- Glove-box equipment mounting bracket

Behind glove box

- Engine compartment: Next to jump-start connection point

Integrated power supply module

Apart from the fuses referred to above, control units haveintegrated electronic circuit breakers which protect components connected directly to the control unit.

-4-


Power module

- General

The power module (PM) is one of the innovative new develop-ments on the E65. Its job is to ensure that the battery charge level is maintained when the engine is running, when it is not running, and in the event of faults in the electrical system.

Components of the power module

- Electronic battery master switch

- High-current sockets

- Inputs

- Outputs connected to electronic battery master switch

- Outputs not connected to electronic battery master switch

- Fuses

- Electronic control unit

-5-


Power module functions

- Optimum charging

- Load-circuit peak smoothing

- Shut-down of auxiliary consumer units

- Quiescent current monitoring

- Distribution mode

- Automatic electrical system isolation

- Load cutout

- Electronic circuit breakers

- Central battery voltage notification

- Rear window defogger

- Interior lighting/forward lighting

- Boot lid and fuel filler flap control

- Data memory

- Failsafe characteristics

- Check control messages

- Diagnosis

-6-


- System overview

KT-8348 Fig. 3: System Summary of power module

-7-


KT-8350

Fig. 4: Power module inputs and outputs

-8-


Index CAS CD

D-Bus DME

BS

DWA

DWA_NS

F1 F2 F3 HHS HKL HKM IB IR K-CAN S K-CAN P

Kombi LM PM

PDC

R RLS S Bat

SBK

Description Car Access System Control Display

Diagnosis bus Digital engine electronics

Battery switch

Antitheft alarm system

Alarm system emergencypower siren

Resettable circuit breaker, CAS

Resettable circuit breaker, DWA

Resettable circuit breaker, DME

Rear window defogger Boot lid lift Boot lid lift module Interior lights Infrared remote control System K-CAN K-CAN PERIPHERIE (peripherals)

Instrument cluster Light module Power Module

Park Distance Control

Terminal R Rain/light sensor Electronic battery masterswitch

Safety battery terminal

Index

SCA

SI GR

SI HSF

SI MR

t˚

TOEHK

TKL

15

15_w

Description

Automatic Soft Close Luggage compartment fuses

Glove-box fuses Engine compartment fuses

Battery temperature sensor

Boot release button, external

Fuel filler flap

Terminal 15

Wake-up lead

30

30U

30B

31

U

UFBD

VA

Terminal 30, battery Terminal 30, SI GR Terminal 30, SI HSF Ground

Voltage regulator Universal radioremote control

Load cutout

VA_D

VA_K

ZGM

ZIG

ZV

Consumer unit isolation, roof zone

Consumer unit isolation, body zone

Central gateway module Cigarette lighter Central locking system

-9-


Pin assignment

32-pin connector

PIN

1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1. 01 1. 11 1. 21 1. 31 1. 41 1. 51 1. 61 1. 71 1. 81 1. 91 1.20 1.21 1.22 1.23 1.24 1.25 1.26 1.27 1.28 1.29

I

I I

Type

O O O O O

Signal designation

Consumer unit isolation, body zone

Terminal 15, cigarette lighter relay

Universal radio remote control

Electrochromic Park Distance Control

O O O O

Alarm system control unit

Alarm system emergency power siren

Infrared remote control (national variant)

Car Access System

O Digital engine electronics

Battery switch distribution mode

Battery switch quiescent current monitoring

K-CAN P Consumer unit isolation, body zone

I/O O

O O O O O I

Rain/light sensor Interior lighting, roof zone

Interior lighting, body zone



Terminal 31 (electronics earth)

Interior lighting button

- 10 -


PIN 1.30 1.31 1.32

I Type Signal designation

Terminal 15 CAS wake-up

I/O Peripherals K-CAN

Pin strip, 13-pin

PIN

2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2. 01 2. 11 2. 21 2. 31

Type

I O O O O

Signal designation

Terminal 31 (load) Automatic Soft Close

Central locking, boot lid drive unit

Fuel filler flap, central locking

Fuel filler flap, central locking

O O M I I I

O

Earth, exterior boot lid button

Luggage compartment light

Terminal 31 (electronics earth)

SCA eccentric contact

Boot lid lock contact

Boot lid button, external

Boot lid warning light

Pin strip, 3-pin

PIN

3.01 3.02 3.03

Type

I

Signal designation

Battery temperature

I Battery temperature

- 11 -


2-pin connector

PIN 1 2

Type O O

Signal designation

Rear window heater (HHS)

Light module (LM)

- 12 -


Installation position of the power module

The power module on the E65 is located in the luggagecompartment on the right.

KT-7741

Fig. 5: Installation position of the power module, rear right

- 13 -


- Components

Electronic battery master switch

The electronic batter master switch is made up of 4 MOS-FEToutput stages (S Bat) and connects the input terminal 30 with the outputs terminal 30U and terminal 30B on the power module.

The following functions are controlled by means of the powermodule according to the position of the battery switch:

- Distribution mode

- Quiescent current monitoring

- Electronic circuit breakers

- Automatic electrical system isolation

High-current sockets

New high-current sockets have been used for the first time.

The high-current sockets are on the input terminal 30 and theoutputs terminal 30U and terminal 30B.

These contacts are capable of carrying transient current peaksof 220 A.

Advantages

- Continuous load capacity of up to 100 A

- Excellent and consistent current conduction over long periods

- Low contact impedance

- Low voltage drop even with large temperature rise

- Consistently good spring characteristics

- Contacts are self-cleaning by virtue of permitted movement

- 14 -


- Inputs

Terminal 30

The battery positive terminal is connected directly to the loadinput of the power module.

Battery switch

The battery switch (BS) offers the vehicle owner and the servicedepartment the choice between the settings ON ("quiescent current monitoring") and OFF ("distribution mode"). It is located above the PM on the right hand side of the luggage compartment.

ON OFF

KT-8288 Interior lighting button

This controls the interior lighting and is located on the frontinterior lighting unit. The possible settings are "Automatic control", "On" and "Off".

Exterior boot lid release button (TOEHK)

The boot lid is released by means of the button on the outside ofthe boot lid.

- 15 -


Central locking switch

The switch in the central locking motor lock in the boot lid isused to release the central locking motor in the boot lid and to synchronise the SCA.

SCA eccentric contact

This controls the SCA motor, the luggage compartment lighting,the monitoring of the alarm system and the boot lid warning light.

15_w

This is a duplicated signal from the car access system whichwakes up the power module.

Battery temperature sensor

Measures the temperature directly on the battery negativeterminal. This information is used by the "optimum charging" function.

K-CAN peripherie

Enables communication with the other control units.

- 16 -


- Outputs connected to electronic battery master

switch

Terminal 30U

Supplies the fuse box in the luggage compartment.

Terminal 30B

Supplies the fuse box in the glove compartment.

- Outputs not connected to electronic battery

master switch

The following outputs are separated from the electronic batterymain switch from the PM:

- Rear window heater (HHS)

- Light switch centre (LSZ)

- Car Access System CAS

- Alarm system (DWA)

- Emergency power siren (NS)

- Infrared remote control (IR, national variant)

- Cigarette lighter (ZIG, national variant)

- Universal remote control (UFBD, national variant)

- Electrochromic rear view mirror (EC)

- Park Distance Control (PDC)

- Rain/light sensor (RLS)

- Interior lighting (IB)

- Central locking, boot lid

- Central locking, fuel filler flap

- SCA, boot lid

- 17 -


The advantages of this arrangement are:

- The exterior lights also function when the electronic battery main switch is open (for safety reasons)

- The anti-theft alarm (DWA) always remains armed

- No additional fuses and wiring for actuators close to the installation position

Fuses

The outputs for the rear window heater, terminal R andterminal 15, are not protected by conventional fuses. They are supplied via a power semiconductor (MOS-FET) in the power module. By measuring the current and comparing it with stored threshold levels, the power module can detect a short circuit and disconnect the circuit accordingly.

The outputs for CAS, DWA and DME are via reversible fuses.

- 18 -


- Functions

Optimum charging

The battery voltage can fluctuate between 14.0 V and 15.5 V.

The optimum charge voltage is set according to the charge levelof the battery, the battery temperature and the condition of the lamps. The maximum setting is 15.5 V.

Battery charge level detection

The power module knows what the charge level of the battery isat any time by calculating the battery current when the vehicle is being driven and measuring the discharge current.

When the vehicle is not in use, the charge level is re-calculatedand updated by measuring the quiescent battery voltage.

Temperature-dependent battery charge voltage

By referring to a charging characteristic map stored on the PM,the charge voltage of the alternator is adjusted according to the battery temperature.

KT-8333

Fig. 6: Data flow from power module to alternator

- 19 -


Increasing idling speed to improve battery charging

In order to drain as little energy as possible from the battery -particularly in the winter - the idling speed is increased at an early stage. This ensures that the battery charge level is kept high.

If the charge level falls below the calculated minimum level forstarting, the idling speed is increased to 750 rpm.

The calculation of the minimum level takes account of theseasonal temperature and the age of the battery.

Load-circuit peak smoothing

If battery discharge is detected while the engine is running(despite increased idling speed), the power supply to electrical consumer units is gradually reduced or completely shut off according to a table of priorities.

These consumer units are:

- Rear window heater

- All seat heaters

- Heater fan (except defrosting)

- Steering wheel heater

- Mirror heater

- Wiper park-position heater

- 20 -


Shut-down of consumer units in the event of low voltage

If the battery voltage drops below 10.5 V (for 5 seconds) due tohigh load levels, the power module sends out an instruction to increase the idling speed and to activate prioritised shut-down of electrical consumer units. At the same time, the power outputs of the power module (interior lights, isolation of consumer units in roof/body zones) are switched off. The following check control message appears:

Check control message Power module! Drive with moderation

in the Control Display

"Power module in emergency mode."Electrical power supply at risk. Have the problem checked by the nearest BMW dealer.

Cause

Power module in emergency mode

KT-8446

Shut-down of auxiliary consumer units

Auxiliary consumer units are items such as AHM, CD, DWA,LSZ, EGS, IHKA and SH.

In order to ensure that the car is capable of starting, the chargelevel of the battery is also monitored when the vehicle is not in use.

The minimum battery charge level required to ensure that the carcan be started again is calculated. That calculation takes account of:

- Outside temperature measured over last few days

- Engine type

- Capacitance of fitted battery

If the charge level of the battery gets close to that minimum levelas a result of the running of an auxiliary consumer unit, the power module instructs that unit to switch off.

Load cutout

In order that the battery is not discharged when consumer unitsare left continuously on (IB, VA_K und VA_D), they are switched off centrally 16 minutes after terminal R is switched off.

- 21 -


Quiescent current monitoring

When terminal 0 is active, the PM switches over to quiescentcurrent monitoring after 60 minutes. If an operation is performed on the car before 60 minutes has elapsed (e.g. central locking, boot opened), the timer starts from the beginning again.

Once that period has elapsed, the quiescent current should notexceed 80 mA. If the quiescent current does exceed 80 mA, after 5 minutes the PM issues the "Shutdowncounter" message. After a further 90 seconds, the vehicle's electrical system is shut down for 5 seconds.

If the quiescent current still exceeds 80 mA when the system isswitched on again, the sequence described above is repeated.

If the quiescent current is then still over 80 mA, the system ispermanently shut down via the battery master switch.

The fault is recorded in the power module's fault memory (withdetails of peripheral conditions and cause, high quiescent current). For more details, refer to the section on fault diagnosis.

When the signal terminal 15_w is detected, the electronicbattery main switch is closed.

- 22 -


Distribution mode

By switching over the battery switch, the power module goesinto distribution mode 30 minutes after terminal R switches off. Before disconnecting, the PM sends out the "Shutdown" signal. After a further 90 seconds, the shut down is executed.

After ignition lock position terminal R On, a Check Controlmessage is sent.

When the signal terminal 15_w is detected or the battery switchis set to "quiescent current monitoring", the electronic battery main switch is closed again.

Automatic electrical system isolation

If no function of any kind is activated over a period of 3 weeks,the battery is disconnected from the vehicle electrical system. This prevents battery discharge.

- 23 -


Electronic circuit breaker

If a short circuit current of over 250 A is detected, the batterymaster switch is opened. Only when the wake-up signal 15_w from the CAS is detected is an attempt made to close the battery master switch again.

This procedure is repeated continually until the short circuit hasbeen eliminated.

Central battery voltage notification

The power module continuously measures the battery voltage.This information is made available to all other control units via the bus link. This can be used, for example, to enable continuous running of the sliding/tilting sunroof regardless of battery voltage.

Central battery voltage notification dispenses with the need forindividual measurement of battery voltage by each control unit.

Rear window heater (HHS)

The electronic rear window heater output stage on the PM isactivated by a "HHS On" K-CAN message from the IHKA control unit.

- 24 -


Interior lights

The interior lighting is subdivided among three outputs (groups).

- IB

- VA_K

- VA_D

(interior lighting)

(consumer unit isolation, body zone)

(consumer unit isolation, roof zone)

The interior lights are controlled by the power module (PM).

VA _K and VA_D are switched on/off according to the status ofthe relevant contacts.

Boot lid and fuel filler flap control

The power module controls the following boot-lid relatedfunctions of the body-zone electronics:

- Boot lid lock

- Boot lid automatic soft close

- Fuel filler flap lock

Data memory

The data memory stores data relevant to the vehicle. That infor-mation provides a status read-out of the battery load and life. It can be accessed by way of the diagnosis function.

The data memory will be used in future to obtain a load profile ofthe battery in normal operation that will be analysed for the purposes of "condition based servicing".

- 25 -


- Diagnosis

All inputs/outputs that are part of the power module functionscan have their status checked by diagnosis functions.

The outputs can also be activated by component activation andthe power consumption displayed.

The following statuses can be read off:

- Present alternator current

- Present battery current

- Present electrical system current

- Present consumer unit current

- Charging balance

- Battery charge level

- Battery temperature

All electronic circuit breakers and the electronic battery masterswitch are monitored for short circuits/circuit breaks.

In the event of a fault, an appropriate entry is made in the PM'sfault memory and, if appropriate, a check control message initiated.

- 26 -


- Notes for Service

Battery charging

As with previous models, a battery charger can be connected inthe engine compartment to the battery earthing point or directly to the battery at the back. The PM detects an external battery charger if UBatt > 13.2 V for 1 hour without the engine running. Following detection of external battery charging, a battery charge level of 80% is reported to the diagnosis function even if the charge level is higher or lower than that figure.

Cigarette lighter battery charging function

A trickle charger can also be connected to the cigarette lighter.However, the cigarette lighter is supplied by the body-zone consumer unit isolation circuit via a relay. If the "Terminal R Off" signal is present for more than 60 minutes, that relay will be tripped by the consumer unit shutdown function. That would mean that a charger connected to the cigarette lighter would be disconnected from the battery. To prevent this, the consumer unit shut-down function can be deactivated. This is performed by the following procedure:

Switch battery switch off on again twice within two seconds.

Battery switch procedure

Initial position

ON ON OFF ON

Step 1

OFF OFF

Step 2

ON

ON OFF

Step 3

OFF

ON OFF

Step 4

ON ON OFF

KT-8288 KT-8288 KT-8288 KT-8288 KT-8288

Direction of movement ® ∠ ® ∠

The function is cancelled by:

- "Terminal 15 On" or

- Switching the battery switch from "OFF" > "ON"

- Battery voltage of 12.6 V not reached after 6 hours of charging.

- 27 -


Electrical system

General

The safety and comfort of cars are continually advancing. Legalrequirements relating to fuel consumption and exhaust emissions can now only be met by the use of more electronic components (e.g. control units, actuators and sensors) in vehicles.

Originally autonomous processes controlled by individualcontrol units are increasingly being linked to one another via bus systems. That means that the processes are shared out, are processed globally and interact with one another in a co- ordinated manner.

As a result, the exchange of data across the vehicle's electricalsystem is increasing rapidly. And because of that exchange of information, many new functions are being made possible.

The consequences of this trend are greater vehicle safety,superior ride comfort and improved fuel economy.

However, such continuing advances can no longer be achievedwith conventional electrical systems.

- 28 -


Bus systems

Bus systems enable the individual control units on the vehicle tobe networked with one another via "serial interfaces".

With the arrival of the E65, three new bus systems have beenintroduced. Two of them are based on fibre-optic technology.

The two new fibre-optic bus systems are called

MOST bus (Media Oriented System Transport)

"byteflight" (safety systems bus)

The third bus system consists of two insulated copper-twistwires and is called the

K-CAN (Body Controller Area Network)

The K-CAN bus replaces the K bus (body bus, in volumeproduction since 09/1992) and is subdivided into two sections.

Comparison of E38 and E65 bus systems

E38

CAN

I bus K bus P bus

--

--

D bus

E65

PT CAN

K-CAN SystemK-CAN PERIPHERIE

MOST bus

byteflight

D bus

- 29 -


E38 bus parameters

I/K/P bus

Data rate

Bus structure

CAN Dbus

9.6

------

KBd 9.6

linear

500

linear

E65 bus parameters

Sub- bus

Data rate

Bus structure

KBdMBd

9.6

K-CAN P

100

K-CAN S

100

PTCAN

500

MOST bus

22.5

byteflight

10

D bus

115

linear linear linear linear ring star ------

- 30 -


- E65 bus system

KT-7323 Fig. 7: E65 bus system

- 31 -


K-CAN Peripherie

Item

CAS D-Bus

HKL

K-CAN P K-CAN S PM SMBF SMBFH SMFA SMFAH TMBFT TMBFTH TMFAT TMFATH

Description

Car Access System

Diagnosis bus

Boot lid lift

K-CAN PERIPHERIE

K-CAN System

Power Module

Seat adjustment module, passenger-side front

Seat adjustment module, passenger-side rear

Seat adjustment module, driver's-side front

Seat adjustment module, driver's-side rear

Door module, passenger-side front

Door module, passenger-side rear

Door module, driver's-side front

Door module, driver's-side rear

- 32 -


System K-CAN

Item

AHM BZM BZMF CAS CIM CD CON D-Bus DWA IHKA

K-CAN S Kombi LM PDC RDC RLS SH SHD WIM ZGM

Description

Trailer module

Control panel module, centre console

Control panel module, rear centre console

Car Access System

Chassis Integration Module

Control Display

Controller Diagnosis bus

Antitheft alarm system

Integrated automatic heating and air conditioningcontrol unit

K-CAN System

Instrument cluster

Light module

Park Distance Control

Tyre pressure control unit

Rain/light sensor

Auxiliary heating

Sunroof Wiper module

Central gateway module

- 33 -


MOST bus

Item

AVT ASK D-Bus CD CDC Kombi MOST bus NAV SVS TEL LOGIC7 VM

Description

Aerial amplifier/tuner

Audio system controller

Diagnosis bus

Control Display

Compact disc changer

Instrument cluster

Media Oriented System Transport bus

Navigation

Voice-input processing system

Telephone interface

Amplifiers Video module

- 34 -


byteflight

Item

byteflight D-Bus SASL SASR SBSL SBSR SFZ SIM SSH SSBF SSFA STVL STVR SZL ZGM

Description

byteflight Diagnosis bus

Satellite, A-pillar left

Satellite, A-pillar right

Satellite, B-pillar left

Satellite, B-pillar right

Satellite, vehicle centre

Safety Information Module

Satellite, rear seats

Satellite, passenger's seat

Satellite, driver's seat

Satellite, front door left

Satellite, front door right

Steering column control centre


- 35 -



Powertrain CAN

Item

ARS D-Bus DME DSC EDC-K EGS EMF GRS PT CAN ZGM

Description

Active body-roll stabilisation

Diagnosis bus

Digital motor electronics

Dynamic stability control

Electronic Damping Control Concept

Electronic transmission control

Electromechanical parking brake

Yaw rate sensor

Powertrain CAN


- 36 -


- E65 sub-bus systems

In addition to the bus systems, sub-bus systems are also used.These are subordinate serial bus systems. Their functions corre- spond to those of the previous I/K bus.

The following sub-bus systems are fitted in the E65:

Engine LoCAN (engine Low CAN bus; link between DME andValvetronic control unit)

TelCommander CAN (Telephone Commander CAN)

M bus (air-conditioning motor bus)

TAGE K bus (door-handle module body bus)

Driver's door K bus (driver's door switch block body bus)

DWA K bus (alarm system body bus)

I bus Japan (instrument bus for Japan)

BSD interface (bit-serial data interface)

- 37 -


Gateway

- General

A gateway (GW) is a sort of "interface". It connects different bussystems within the vehicle electrical system. This ensures data and information exchange in spite of different transfer rates of the individual bus systems.

Diagnostic access to the individual control units is now possiblevia the ZGW.

- Method of operation

The data transmitted by the various bus systems is received bythe gateway. At this point, transmission rates, data and priority levels of the individual messages are filtered and temporarily stored if necessary. This requires a non-volatile memory.

Diagnostic

PT-Wake-up lead

KT-8136

Fig. 8: Communication channels within the gateway

Using gateway rules and conversion tables (GW-T), the gatewayconverts the messages as required by the various bus systems concerned. The messages are then passed to the various bus systems via which they reach their ultimate destinations. If necessary, messages that are relatively less important are held in the gateway's memory and sent "later".

- 38 -


Overview of E65 gateways

KT-8293

Fig. 9: Gateways on the E65

Item

ZGM

CAS

Description Central gateway module

Car Access System

Item

CD

Description

Control Display

- 39 -


Optical waveguides

- General

Transmission of data, voice and images involves ever increasingvolumes of data.

Fibre-optic cable technology (already in use in telecommunica-tions and industrial installations) is capable of handling such large volumes of data while at the same time offering additional advantages.

High data transmission rates in copper wires cause electromag-netic irradiation. This can interfere with other vehicle systems.

Compared with copper wires, fibre-optic cables (opticalwaveguides) require less space and are lighter in weight for the same transmission band width.

In contrast with copper wires, which carry digital or analoguevoltage signals as the means of transmitting data, fibre-optic cables transmit light.

The most commonly used fibre-optic cables are:

- Plastic optical waveguides (K-LWL)- Glass optical waveguides

- 40 -


- Structure of plastic optical waveguides (LWL)

KT-8939 Fig. 10: Cross section of plastic optical fibre

Index 1 2

Description Padding sleeve Cladding

Index

3

Description

Fibre core

For both the optical waveguides byteflight and MOST, the fibrecore is made of plastic.

The plastic optical waveguide (K-LWL) has the following advan-tages compared to the glass optical waveguide (G-LWL):

Large fibre cross section

Because of the large cross section of the fibres, the positioningof the fibre core does not present a significant technical problem in production.

Relatively low sensitivity to dust

Even with the most careful precautions, dust can find its wayonto the surface and alter the amount of light entering/leaving the optical fibre. Small amounts of contamination do not neces- sarily result in failure of the transmission medium.

- 41 -


Easy to work with

The fibre (core) is approximately 1 mm thick and easier to handlethan glass optical fibre with a thickness of approximately 62.5 ∝μμ, for example. In comparison with a glass fibre-optic cable, it is considerably easier to handle. Note: glass breaks and plastic doesn't.

Processing

The optical fibre material used by BMW is polymethyl methacr-ylate (PMMA) which, in comparison to glass optical fibres, is relatively easy to cut, smooth down or melt - which offers major advantages with regard to the production of wiring looms and in repair work.

- Colour coding of optical waveguides

In order to be able to distinguish the optical waveguides for thevarious bus systems, there are currently 3 different color markings:

Yellow

Green

Orange

byteflight

MOST

Service repair line

- 42 -


- Data transmission function by means of light

impulses

KT-8853 Fig. 11: Principle of transmission by means of light

Index 1 2

Description Transmitter diode Cladding

Index

3

4

Description

Fibre core

Receiver diode

The electrical signal generated by the control unit is convertedinto an optical signal by a transmitter module and sent along the optical fibre. The fibre core carries the light beam. In order to prevent the light escaping, the fibre core is enclosed by a cladding layer. The cladding is reflective and reflects the light back into the core, thus making it possible to transmit light along the fibre.

In this way, the light passes along the optical fibre and isultimately converted back into an electrical signal by a receiver module.

- 43 -


- Structure of MOST bus

KT-8788 Fig. 12: MOST bus components

Index D-Bus ZGM

K-CAN S CD

Kombi ASK TEL

Description Diagnosis bus Central gateway module

System K-CAN Control Display Instrument cluster Audio system controller

Telephone

Index

NAV

SVS

LOGIC7

AVT

CDC

MOST

Description

Navigation

Voice processing system Amplifiers

Aerial amplifier/tuner CD changer

MOST bus

- 44 -


- Functional description of MOST

The MOST bus transmits all data required by the communicationand information systems in the vehicle. MOST stands for Media Orientated Systems Transport.

The connection between the individual control units is providedby a ring bus which transports the data in one direction only.

That means that a control unit always has two optical fibrecables - one for the transmitter and one for the receiver.

The MOST control units are linked exclusively by fibre-opticconnections. Transmitter and receiver diodes can thus also be placed anywhere in the control unit because of the fibres it contains.

KT-8887 Fig. 13: Optical fibre routing inside a control unit

Index 1

2

Description Fibre-optic connector

Socket on control unit

Index

3

4

Description

Optical fibre inside thecontrol unit

Receiver module

As a result, the fibre ends can be set back inside the wiring loomconnector. This provides additional protection for the sensitive fibre ends.

- 45 -


KT-8852 Fig. 14: Connector for use in MOST network

Index 1 2

Description Pin 1 - incoming optical waveguide

Pin 2 - outgoing optical waveguide

- 46 -


Structure of byteflight

The byteflight is a part of the overall vehicle circuit in the E65. Itis connected to the K-CAN S, PT-CAN and the diagnostic bus via the Central Gateway Module (ZGM).

Fig. 15: Structure of byteflight

KT-7785

- 47 -


Index

byteflight K-CAN PT CAN SASL SASR SBSL SBSR SFZ SIM SSH SSVL SSVR STVL STVR SZL ZGM

Description

byteflight Body Power Train

Satellite, A-pillar left

Satellite, A-pillar right

Satellite, B-pillar left

Satellite, B-pillar right

Satellite, vehicle centre

Safety Information Module

Satellite, rear seats

Seat satellite, front left

Seat satellite, front right

Satellite, front door left

Satellite, front door right

Steering column control centre

Central Gateway Module

- 48 -


- Functional description of byteflight

In contrast to the MOST bus, the byteflight is a star bus thattransports data in two directions.

That means that there is only one fibre-optic cable for eachcontrol unit. The transmitter is immediately above the receiver. Both are integrated in the pin strip of the control unit.

Due to those differences to the MOST bus, a different connectorsystem is required. As the diodes are directly contacted on the byteflight, the protruding fibre end must be protected against damage and soiling by a cap. This is automatically opened as the connectors are joined up.

KT-8890

Fig. 16: Connector system for byteflight

On the right-hand connector, the grey cap is shifted towards therear (automatically opened as the connectors are joined up). The end of the fibre of the optical waveguide then protrudes.

KT-8948 KT-8947

Fig. 17: Device pin strip

- 49 -


- Attenuation of light impulses

The light impulses guided in the fibre core lose power as theytravel. The natural power loss is termed attenuation. This must not exceed a certain value, as otherwise the receiver module in the corresponding control unit can no longer process the light impulses.

The attenuation can have two main causes:

- Natural attenuation - Defective attenuation

Natural attenuation results from the length of the path that thelight impulses must travel from the transmitter module to the receiver module.

Defective attenuation results from faults in the area of lightimpulse transfer.

KT-8780

Fig. 18: Attenuation of light in an optical fibre

Index

1 2

Description

Transmitter diode Cladding

Index

3

4

Description

Fibre core

Receiver diode

- 50 -


- Faults and their causes

A measure of the signal quality is the attenuation. Excessiveattenuation can be caused by a number of reasons:

- Bends in the fibre-optic cable with a radius of < 5 cm

- Kinks in the fibre-optic cable

- Squashed or compressed fibre-optic cable

- Damaged padding sleeve on fibre-optic cable

- Stretched fibre-optic cable

- Dirt or grease on the exposed cable ends

- Scratches on the exposed cable ends

- Overheated fibre-optic cable

- 51 -


Bending radius

The plastic fibre-optic cable should not be bent to a radius ofless than 50 mm. That is roughly equivalent to the diameter of a soft-drink can. Bending the plastic fibre-optic cable any tighter than that can impair its function or even damage it irreparably.

Light can escape at points where the cable is bent too tightly.This is caused by the fact that the light beam strikes the interface between core and cladding at too steep an angle and is not reflected.

KT-8782

Fig. 19: Escape of light due to over-bending

Kinking

Fibre-optic cables must not under any circumstances be kinkedwhen fitted because this damages the cladding and the fibre core. The light is then partially dispersed at the point where the fibre is kinked and transmission loss results. Even kinking an optical waveguide once very briefly is enough to damage it.

KT-8784

Fig. 20: Optical fibre damaged by kinking - 52 -


Compression point

Compression points must also be avoided at all costs becausethey can permanently deform the light-conducting cross section of the optical fibre.

Light is then lost during transmission. Pulling fibre-optic cablestoo tight can also cause compression points as it increases the lateral pressure on the cable.

The effect is exaggerated at higher temperatures because thecable straps then become tighter as well. The fibre-optic cable is then constricted, the attenuation increases at that point and function is severely impaired.

KT-8781

Fig. 21: Compression point on optical fibre

- 53 -


Abrasion points

In contrast with copper wires, abrasion of fibre-optic cablesdoes not cause a short circuit.

Instead, loss of light or intrusion of external light occurs.The system then suffers interference or fails completely.

KT-8940

Fig. 22: Chafing on an optical waveguide with light escaping

- 54 -


Stretched fibre-optic cables

Overstretching of fibre-optic cables, caused by pulling forexample, can destroy them.

Stretching reduces the cross-sectional area of the fibre core.Restricted passage of light (attenuation) is the result.

KT-8785

Fig. 23: Stretched fibre-optic cables

Dirty or scratched fibre-optic cable ends

Another potential source of problems are dirty or scratchedcable ends. Although the ends of the cables are protected against accidental contact, they can still be damaged by incorrect handling. Dirt on the end of an optical fibre will prevent the light entering/exiting the fibre. The dirt absorbs the light and the attenuation is then too great. Scratches on the cable ends scatter light striking them so that the amount of light reaching the receiver is reduced.

- 55 -


KT-8854

Fig. 24: Dirty optical fibre ends

KT-8855

Fig. 25: Scratched optical fibre ends

Overheating of the optical waveguide

The demands of the new technology even have to be taken intoaccount in subsequent repair work such as painting. As fibre- optic cables are damaged by heat, care must be taken to ensure that the maximum permissible temperature of 85 ºC is not exceeded when drying paintwork.

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- Service/Diagnosis

Notes on working with fibre-optic cables

Extreme care is required when working on vehicle wiring loomsas - unlike copper wiring - damage does not immediately result in a fault but only comes to the owner's notice at a later stage.

Notes on repairing optical waveguides

The MOST optical waveguide may be repaired once betweeneach control unit.

The byteflight cannot be repaired at present.

Customer Service will supply pliers for crimping the new "opticalwaveguide sleeves".

The precise procedure will be described in the instructions forusing the crimping tool.

Diagnosis

The diagnosis of the optical waveguide refers to determining theextent of attenuation of the light impulses. Here, measuring equipment will be provided. The precise procedure will be described in the operating instructions.

- 57 -


Diagnosis bus

General

The aim of diagnosis is to enable a service technician to reliablyidentify a defective component.

By the use of appropriate hardware and monitoring software, themicroprocessor of a control unit, for example, is able to detect faults on the control unit and its peripherals. Faults identified are stored in the fault memory and can be read out using diagnosis tools.

Data transfer between the vehicle and the diagnosis tool takesplace via the diagnosis bus (D bus) inside the vehicle.

New features of the diagnosis bus are:

- Faster data transmission speed of 115 kBd

- Central diagnosis access point

- Single diagnostic cable (TxD) for the entire vehicle

Omission of TxD1 cable

- Access to diagnosis functions requires authorisation

- Diagnosis protocol "KWP 2000" (Keyword Protocol 2000)

Standardised diagnosis structure for all control units

Diagnosis concept

The "BMW fast" (BMW fast access for service and testing)diagnosis concept introduced on the E65 is applied. This concept is based on the "Keyword Protocol 2000" (KWP 2000) diagnosis protocol defined as part of the ISO 14230 standard. Diagnosis communication takes place entirely on the basis of a transport protocol on the CAN bus.

- 58 -


Link between D bus and electrical system

The diagnosis bus is connected to the central gateway module.All bus systems, except for the MOST bus, are connected to the ZGM (Central Gateway Module).

KT-8372 Fig. 26: System overview of D bus

Vehicle diagnosis access point

KT-8946

Fig. 27: Location of diagnosis connector

The diagnosis tool is connected to the vehicle by means of thediagnosis connector E-OBD (European On Board Diagnosis).

- 59 -


The TxD lead is connected to Pin 7 of the E-OBD socket. Itconnects that pin directly to the central gateway module.

The central gateway module detects by means of the data trans-mission speed whether a BMW diagnosis tool or another type is connected. The diagnosis messages are identified accordingly.

The DME allows access to different data depending on thediagnosis tool connected.

Note:

When using an E-OBD scan tool for diagnosis, the transmissionspeed is 10.4 KBit/s.

KT-8713

Fig. 28: Transmission speeds

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