1. Contents 1 Basics Drivetrain CAN bus Convenience CAN bus Components
Infotainment CAN bus
( Display CAN )
VW CAN data bus
Audi CAN data bus
Sehr geehrte(r) Trainingsteilnehmer(in),
auf den nachfolgenden Seiten finden Sie, die während des
Training, geforderten Gruppenarbeiten.
Arbeiten Sie in Ihrer Gruppe die vorgegebenen Aufgaben
nach Vorgabe des Trainers ab. Achten Sie bitte darauf, daß
das zur Verfügung stehende Zeitlimit nicht überschritten
wird.
Notizen :
CAN network
Next page
Data protocol
Gateway

2. Contents 2 Fault diagnosis Fault finding with VAS 5051
CAN networked systems
API
Sehr geehrte(r) Trainingsteilnehmer(in),
auf den nachfolgenden Seiten finden Sie, die während des
Training, geforderten Gruppenarbeiten.
Arbeiten Sie in Ihrer Gruppe die vorgegebenen Aufgaben
nach Vorgabe des Trainers ab. Achten Sie bitte darauf, daß
das zur Verfügung stehende Zeitlimit nicht überschritten
wird.
Notizen :
Technical Service
Handbook
CAN fault descriptions
Fault finding in practice
CAN bus in Audi A4

3. CAN Bus CAN data bus Diagnosis interface (gateway) Basics
Drivetrain system (Drivetrain CAN)
for example:
Training Transparencies
Convenience system (Convenience CAN)
Training Worksheet
Dubai

4. Controller Area Network CAN data bus
was developed by the Robert BOSCH company in
1983
as a bus system for cars.
networked control units exchanging data
00/00

5. Intelligent Sensors and Actuators
CAN data bus A S S S A A A S
Central control unit S S A S A A S S A
Intelligent Sensors and Actuators

6. More Sensors and Actuators
CAN data bus
Central control unit
More Sensors and Actuators
K VK-36mz

7. More sensors and actuators
CAN data bus
More control units
More sensors and actuators
More wiring and wiring harnesses
Limited construction space
Convenience functions require data exchange

8. CAN data bus
e.g. networking door
Maximum 45 wires
9 plugs
Up to 60 wiring variations
without CAN

9. Networking with control units
What solution ?
Networking with control units

10. Drivetrain CAN networking with three control units
CAN data bus
Drivetrain CAN networking with three control units
Drivetrain CAN active only when terminal 15 is switched on.

11. CAN data bus e. g. networking door Maximum 17 wires 2 plugs
2 wiring variations
Data exchange with CAN data bus (low speed CAN) (2 data wires)
with CAN

12. Parallel data transfer
Receiver
Sender
Parallel data transfer

13. Throttle valve position Engine intervention (torque)
CAN data transfer
Control unit 1
Control unit 2
Engine speed
Fuel consumption
Throttle valve position
Engine intervention (torque)
Up/down shift points

14. Data transfer
Receiver
Sender
Serial data transfer

15. Convenience CAN always active,attached to terminal 30 ! (Sleep mode)
CAN data bus
Drivetrain
Convenience system
Convenience CAN always active,attached to terminal 30 ! (Sleep mode)

16. Automatic gearbox control unit
CAN data bus
ABS/EDL control unit
Automatic gearbox control unit 1
Engine control unit 3
Data bus wires 2
Priority

17. CAN data bus 1 2 3 4 Priority Data protocol from ... Information
- Engine Braking Ctrl. requirement
ABS/EDL control unit 1
- Traction Control requirement
- Engine speed
Engine control unit
data protocol No. 1 2
- Throttle valve position
- Kickdown
Engine control unit
data protocol No. 2
- Coolant temperature 3
- Vehicle speed
Automatic gearbox control unit
- Selector lever position 4
- Gearbox in emergency running
- Driving range change

18. CAN data bus networking
Central wiring connections
J104
J285
Convenience CAN
(orange-green)
Display CAN
(orange-violet)
Drivetrain CAN
(orange-black)
Drivetrain CAN
J220
J217
Änderung Verknüpfung der Datenbusleitungen am Audi A4 2001>
Zentrale Leitungsverknüpfung erleichtert die Fehlerdiagnose
Bei einem Kurzschluss besteht hier die Möglichkeit zur weiteren Fehlersuche die Leitungen zu den einzelnen Steuergeräten zu trennen.
Die Unterbrechung einer Verbindung hat nur den Ausfall der Botschaften eines Steuergerätes zur Folge
Ausnahme: CAN Antrieb:
Im Motorsteuergerät ist der zentrale Abschlußwiderstand (60 Ohm)des CAN - Antrieb integriert.
Ist die CAN - Verbindung zum Motorsteuergerät unterbrochen so fällt der gesamte CAN - Antrieb aus.
J234
G85
A-pillar, left
A-pillar, right

19. Baud rate : 5 x higher or faster
CAN data bus
Data bus transfer speed :
Control unit 1
Control unit 2
Message duration :
Bit time 10 s
100 kBaud/s
100,000 bits/s
8 Bytes 1.1ms
Convenience CAN data bus
Bit time 2 s
500 kBaud/s
500,000 bits/s
8 Bytes 220s
Drivetrain CAN data bus
Baud rate : 5 x higher or faster

20. Convenience CAN data bus
Data bus transfer speed :
Control unit 1
Control unit 2
OLD
65 kBaud/s
65,000 bits/s
Convenience CAN data bus
NEW
Convenience CAN data bus
100 kBaud/s
100,000 bits/s

21. Twisted, unshielded two-core wire Ø: 0.35-0.50 mm2 twist length: 20 mm
CAN data bus wiring
Control unit 1
Control unit 2
Colours :
High orange/green
Low orange/brown
Convenience CAN bus wire
Twisted, unshielded two-core wire Ø: mm twist length: 20 mm

22. CAN data bus wiring
Drivetrain CAN
High or/bk
Low or/br
Convenience CAN
High or/gn
Low or/br
Infotainment CAN
High or/vio
Low or/br

23. CAN data bus Control unit 1 Control unit 2 CAN bus wiring
Matching resistor
CAN bus wiring

24. CAN wiring
Matching resistance cannot be determined by measuring resistance because the matching resistors are not connected directly but via the CAN transceiver.
Matching resistors
5.6 K
CAN High
CAN Low
560 
In every control unit, there are matching resistors of varying values. Because they are wired in parallel, the sum of all resistance lies between 100 – 300 

25. 560  CAN wiring Matching resistors
CAN High
CAN Low
560 
CAN-capable dash panel insert, currently...
2 x 1.3 K matching resistors in drivetrain CAN
2 x 560  matching resistors in convenience CAN

26. CAN data bus Task Control unit 1 Control unit 2 Control unit 3
Assume data
Make data available
Assume data
Check data
Check data
Check data
Receive data
Receive data
Receive data
Send data

27. CAN data bus
From model year ´95 CAN bus technology at Audi (in A8)
This technology already extensively controls overall vehicle communication in Audi A2 and A4.
This technology requires from the service personnel a high degree of technical knowledge in order to perform targeted fault finding in the event of faulty performance.

28. CAN networking
Drivetrain CAN
Convenience CAN
for example :
2000 Passat

29. to dash panel (Gateway)
CAN networking
K wire
to dash panel (Gateway)

30. CAN networking Drivetrain CAN Info CAN K wire Convenience CAN MFW RNS
DSP
Convenience CAN

31. CAN networking
Drivetrain CAN
Info CAN
K wire
Convenience CAN

32. CAN networking
Drivetrain CAN
Info CAN
K wire
Convenience CAN

33. CAN bus networking AUDI A2
3-wire
Chorus
radio
Diagnosis
KWP 1281
single DIN
Gateway
SOS
Driver door mod.
Pass. door mod.
K wire
Engine electronics
MFW
Rear door module
Rear door module
Gearbox
electronics
NS low
Running gear elect.
Conv.
electr.
Air con.
Telematics
incl. phone
Steering
angle sens.
Parking aid
Symphony
radio
Steering
aid
Convenience bus 100 kBaud
Display CAN 100 kBaud
Drivetrain bus 500 kBaud
SOS : Speech Operation System MFW: Multi-Function Steering Wheel

34. Drivetrain CAN (500 kBaud)
CAN data bus
Bus systems
Dash panel insert
Gateway
Convenience
Drivetrain
Infotainment
At , the convenience and the infotainment data busses are physically one bus system (no separate wires) however, with separate software.
Drivetrain CAN (500 kBaud)
Convenience CAN (100 kBaud)
Infotainment CAN (100 kBaud)

35. Drivetrain CAN (500 kBaud)
CAN data bus
Bus systems
Dash panel insert
Gateway
Drivetrain
Convenience
Infotainment
At , the convenience and the infotainment data busses are physically one bus system (no separate wires) however, with separate software.
Drivetrain CAN (500 kBaud)
Convenience CAN (100 kBaud)
Infotainment CAN (100 kBaud)

36. Bus systems 3-wire Chorus radio Diagnosis KWP 1281 single DIN Gateway
SOS
Driver door mod.
Pass.
Door mod.
K wire
Engine electronics
MFW
Rear
door mod.
Rear
door mod.
Gearbox
electronics
NS low
Conven.
elect.
Air
con.
Running gear elect.
Telematics
incl. phone
Steering
angle sens.
Parking
aid
Symphony
radio
Steering
aid
Convenience bus 100 kBaud
Display CAN 100 kBaud
Drivetrain bus kBaud
SOBS : Speech Operation System MFW: Multi-Function Steering Wheel

37. Drivetrain CAN data protocol
Bus signal

38. Data protocol
Bus signal

39. Data protocol
Bus signal

40. Verification field 2 bits
CAN data bus
Data protocol
Not used
1 bit
Start field
1 bit
Data field
max. 64 bits
Verification field bits 01 1
Status field
11 bits
Check field
6 bits
Security field bits
End field 7 bits

41. CAN data bus Contents 0000 0000 0000 0000 0000 0000 Possible
Information
Bit variation
with 1 bit
with 3 bits
with 2 bits
Bit variation
with 1 bit
Bit variation
with 1 bit
Bit variation
with 2 bits

42. CAN data bus Contents 0000 0000 0000 0000 0000 0000 Possible
Information
Bit variation
with 1 bit
with 3 bits
with 2 bits

43. CAN Datenbus Inhalt 0000 0000 0000 0000 0000 0000 Bit variation
with 1 bit
Possible
Information
Bit variation
with 2 bits
Possible
Information
Bit variation
with 3 bits
Possible
Information

44. 8-bit information packets are transmitted ( 0000 0000 )
CAN data bus
8-bit information packets are transmitted ( )
e.g. throttle valve position
256 variations Throttle valve positions in steps of 0.4°
Bit sequence
Throttle valve setting
000.0° Throttle valve opening angle
000.4° Throttle valve opening angle
000.8° Throttle valve opening angle
034.0° Throttle valve opening angle
102.0° Throttle valve opening angle

45. Data protocol

46. Communication under real time conditions
CAN data bus
Communication under real time conditions
Real time conditions are events synchronised with the crankshaft in fixed time grid with cycle times of a few milliseconds.
Ignition impulses in a 6-cylinder engine
Engine speed 6000 rpm
Time span 3.3 ms
Calculation in control unit 1
Actual transmission
Trigger event
Start
1.5 ms
1.8 ms
2.0 ms
2.5 ms
3.0 ms
3.3 ms
Measurement
Transmission request
Calculation in control unit 2
End

47. Drivetrain CAN data bus
CAN High wire 5 V (actual value ca. 4 V)
CAN Low wire 0 V (actual value ca. 1 V)
In practice, the values are less than 5 V and greater than 0 V.
Amount of deviation depends on the number of CAN participants.
0 V
5 V

48. Task
Group work
Determine the actual CAN values on the training model and on the test vehicle.
Training model :
H : Volt L : V
Time : min.
0 V
Vehicle :
H : Volt L : V
5 V

49. Convenience CAN data bus
Rear right control unit
Rear left control unit
Front passenger control unit
Driver side control unit
Main convenience control unit

50. Convenience CAN data bus Convenience (CL) control unit
Gateway control unit
Memory control unit
Data bus
Data bus
Data bus
Data bus

51. Convenience CAN data bus
Bus o.k.

52. CAN data bus
Ignition off
dominant
3.6 V
recessive

53. CAN data bus
Ignition off
11.5 V
5 V
3.6 V
1.4 V

54. CAN differential signal CAN H - CAN L = CAN Differential signal
3.75 V
2.50 V
1.25 V
CAN L
2.5 V
CAN D
0 V
CAN H CAN L = CAN Differential signal

55. CAN differential signal Electromagnetic interference

56. CAN data bus
Ignition off

57. CAN data bus
active
Ignition off
150mA

58. CAN data bus
active
Ignition off
wait
2 min.
150mA

59. active wait sleep 6 mA CAN data bus
High wire is 0 V when bus is in sleep mode.
The Low wire assumes vehicle voltage.
active
Ignition off
wait
sleep
Alarm
Remote control
Status LED
6 mA

60. active aktiv wait sleep 6 mA CAN data bus
High wire is 0 V when bus is in sleep mode.
The Low wire assumes vehicle voltage.
active
aktiv
Ignition off
wait
sleep
Alarm
Remote control
Status LED
e.g. door opens
6 mA

61. active wait sleep 6 mA CAN data bus Alarm Remote control Status LED
Ignition off
wait
sleep
Alarm
Remote control
Status LED
6 mA

62. CAN data bus
Bus o.k.

63. Task Group work - Answer -
Determine the actual CAN values on the training model and on the test vehicle.
Training model :
H : 4.73 V L : 1.15 V
Time :
min
0 V
Vehicle :
H : 4.71 V L : V
5 V

64. CAN data bus Sources of interference
Within the vehicle, interference is created by components which create sparks during operation or which have circuits which open and close during operation.
Other sources of interference are, e.g. mobile phones and transmitters, anything which creates electromagnetic radiation.
The fields of interference from these sources can influence or falsify data transmission.

65. Convenience CAN data bus
Planned to be added soon to convenience CAN:
Main convenience control unit
Central locking
Theft alarm system
Interior monitoring
- Digital Sound Processing (DSP)
- Multi-function steering wheel
- Radio navigation system
Automatic distance control
Climatronic

66. CAN data bus

67. Diagnosis interface (Gateway)
Training contents
General
Fault diagnosis
Task
Fault finding with VAS 5051
Funktion
VW Gateway
2001 Passat
Audi Gateway
2001 Audi A4
CAN networking
Protected CAN access
00/00

68. Diagnosis interface (Gateway)
General
Diagnosis interface (Gateway) = virtual control unit (software) from model year 2000 located in dash panel insert
Task : Transfer diagnostic data from the CAN bus system to the K wire.

69. Gateway Connected on one side to the diagnosis wire
Convenience
Drivetrain
Infotainment
and on the other, to all CAN bus systems.

70. Gateway
General
Skoda (Fabia) gateway in onboard power supply control unit
Generation
Polo as well as Golf
year 2002
will be equipped with a separate onboard power supply control unit with integrated gateway.
Onboard power supply control unit

71. Gateway Task as diagnosis gateway... as data gateway…
To transfer diagnosis messages from
drivetrain, convenience and infotainment CANs
to the K wire without altering the data.
To enable data exchange or communication among the participants in a bus and among the various bus systems.

72. Gateway Task To put together data telegrams Drivetrain CAN 500K/b
Convenience CAN 100K/b
Infotainment CAN (at Audi) 100K/b
The various bus systems must be linked frequency-neutral.

73. Gateway (interface) Data signal Example : Drivetrain CAN Speed signal
The speed signal is generated in the drivetrain CAN by the dash panel insert. This signal is needed by nearly all control units. The gateway manages the transfer of this data telegram to the drivetrain CAN as well as the other CAN systems, e.g. convenience CAN.
Convenience CAN

74. Convenience control unit
Gateway
Function
Engine control unit
For the transfer, the gateway opens a bi-directional channel in which it alone communicates with recipient addressed via the K wire.
Drivetrain CAN
The gateway control unit is adjusted according to the CAN participants (installation list).
Diagnosis connection
Convenience CAN
Convenience control unit

75. Gateway Software list Function
There is an installation list on control units which serve in vehicles as CAN nodes.
The installation list comprises various items of information.
They are, specifically…
..always installed
..via coding
..via self-identification

76. Gateway Installation list ..always installed
e.g. engine control unit / dash panel control unit
Determined by part number of dash panel insert

77. Gateway Installation list ..via coding
The gateway must be informed by means of coding of CAN participants which are not always installed.
e.g. gearbox electronics

78. Gateway Installation list ..via self-identification
Self-identification functions through the network management in every control unit, that is, certain control units no longer must be coded.
e.g. radio
Convenience CAN participants are recognised on the basis of the network management.
Currently the automatic gearbox, the Haldex coupling, the steering angle sensor and the diesel pump in the V6 TDI are excluded.

79. 19 Gateway (interface) At , the gateway has its own address word.
The gateway is informed of CAN participants via the function
Coding 07.

80. 19 Data gateway (interface) Gateway Coding e.g. 00006
for airbag and ABS
For current coding, refer to valid workshop literature (ELSA)

81. 19 Data gateway Gateway Fault memory Group data bus faulty (bus off)
short between wires
No communication (time out)
short between wires
One-wire mode
Convenience data bus in one-wire mode

82. 19 Data gateway Gateway Measured value block drivetrain CAN
125 Engine/gearbox/ABS/ -----
126 Steering angle/airbag/steering/
diesel pump
127 Electric central locking / Haldex / ADC/ Climatronic

83. 19 Data gateway Gateway Measured value block convenience CAN
130 Single wire/double wire/central module/driver door/passenger door
131 Serial number/rear left door/ rear right door/memory
132 Dash panel insert/steering wheel/tyre pressure control

84. 19 Data gateway Gateway Measured value block convenience CAN
133 Electric roof/passenger memory seat/rear memory seat
140 One wire/two wire/radio/ navigation/phone
141 Speech operating system/CD changer/TV tuner

85. Data gateway (interface)
At , the gateway is informed with the function: Adaptation with the address word
Dash panel insert 17
Through channel of participants in drivetrain CAN
Through channel of participants in convenience CAN
Through channel of participants in infotainment CAN

86. Data gateway 17 Dash panel insert Measured value block convenience CAN
125 Drivetrain CAN data bus (engine/gearbox)
126 Drivetrain CAN data bus (air conditioning)
130 Convenience CAN data bus (tyre pressure control/acoustic parking system)
131 Display CAN data bus (central electronics/steer- ing angle sensor/air conditioning/one or two-wire mode)

87. Data gateway 17 Dash panel insert Measured value block convenience CAN
140 Display CAN data bus
(radio/navigation)
means participant in CAN data bus, empty field means no participant in CAN

88. Protected CAN access It is planned....
External protected CAN access for Service (KD) and Production.

89. Protected CAN access
With a login procedure, the CAN systems can be enabled for direct access via the diagnosis connector.
Converter

90. Protected CAN access
Login CD
Converter

91. Entry in TSH
last 91

92. CAN Bus Training Worksheet CAN bus Diagnosis and fault finding
Training Transparencies
Part 2
Training Worksheet
K VK-36mz
Dubai

93. CAN bus Possible faults Open wires Data bus “xy” faulty
Matching resistance
Data bus “xy” faulty
Data bus “xy” no communication

94. CAN cus Possible faults Short circuits Data bus „xy“ in one-wire mode
(convenience/infotainment)

95. Control unit -failure-
CAN bus
Possible faults
Control unit -failure-
If a control unit which is included in the specification list and which is required for functionality is not present in the CAN, the message (for respective CU)
Control unit “XY” no communication or Group data bus “XY”
missing message
will be saved.
Control unit “xy” no communication
Group data bus “xy”
message missing
Participant present according to gateway installation list but not present in network.

96. Loss of individual messages from CU
CAN bus
Possible faults
Loss of individual messages from CU
If the “bus off” state occurs twice in succession without communication between them, i.e. without successfully transmitting a “send command” and without successfully receiving CAN telegrams, the control unit must enter the fault
“Convenience Group data bus faulty”
with its own diagnosis wire.
Group data bus “xy” faulty

97. CAN bus Possible faults Faulty messages Data bus “xy” in one-wire mode
Bus participants with their own diagnosis wires (e.g. gateway, combi, (Audi onboard power supply control unit))
save the one-wire fault as “convenience data bus in one-wire mode” if one-wire fault messages are present
for one second during a complete CAN message round with 20 participants
or for a complete CAN message round if there are fewer participants.
Data bus “xy” in
one-wire mode
(convenience/infotainment)

98. Gateway
is connected on one side with the diagnosis wire (K wire)
Diagnosis
Convenience
Drivetrain
Infotainment
and on the other side with all CAN bus systems.

99. Gateway Diagnosis Read fault memory in diagnosis gateway (19)
Convenience
Drivetrain
Infotainment
In addition, read the fault memories of all connected control units.

100. Engine electronics control unit
Drivetrain data bus
Message from airbag control unit missing sporadic
Message from gearbox control unit missing sporadic
Message from combi-instrument missing sporadic
K VK-36mz

101. Which control units are in the drivetrain CAN ?
K VK-36mz

102. Gateway 19 Drivetrain CAN J 220 J 533 J104 G 85 J248 J217 J234 K wire64
T 32b/19 66
T 32b/20
A122
J104
G 85
J248
J217
J234
K VK-36mz

103. Bus o.k.
K VK-36mz

104. Bus o.k.
K VK-36mz

105. Drivetrain CAN K VK-36mz Drivetrain data bus
Message from airbag control unit missing sporadic
Drivetrain data bus
Message from gearbox control unit missing sporadic
Drivetrain data bus
Message from combi-instrument missing sporadic
K VK-36mz

106. Fault signals
K VK-36mz

107. K VK-36mz

108. K VK-36mz

109. K VK-36mz

110. Convenience CAN X
Open circuit
K VK-36mz

111. Entry in fault memory Convenience CAN
Door control unit rear left -J388
no communication
Diagnosis interface for data bus -J533
no communication sporadic
K VK-36mz

112. Convenience CAN
Bus o.k.
K VK-36mz

113. Convenience CAN
Bus o.k sleep mode-
K VK-36mz

114. Convenience CAN
K VK-36mz

115. Convenience CAN
K VK-36mz

116. Convenience CAN
K VK-36mz

117. Convenience CAN
K VK-36mz

118. Convenience CAN
K VK-36mz

119. Convenience CAN
K VK-36mz

120. ?
K VK-36mz

121. Practical experience on vehicle Practical experience on model
CAN systems
for example
Practical experience on vehicle
Practical experience on model

122. Practical experience on vehicle
CAN systems
Measurements with VAS 5051
for example
DSO  CAN High
DSO  CAN Low
1. CAN bus open circuit
2. CAN bus short circuit between wires
3. CAN bus short circuit to +
Practical experience on vehicle
4. CAN bus short circuit to -

123. e.g. Connector point, front left
Convenience CAN
e.g. Connector point, front left
Ursache :
Self-made adapter

124. API Technik direct
Controller
Area
Network

125. Self-made adapter for Convenience CAN check
Positive
Negative
CAN High Pin 2
CAN Low Pin 3 1J
Plug housing black 1J
K VK-36mz

126. Convenience CAN
K VK-36mz

127. CAN systems
Engine 1
Gearbox
ABS/EDL 1
Gateway 1
125
K VK-36mz

128. Which control units are present in CAN ?
CAN systems
Which control units are present in CAN ? ? x ? x ? x ? x
127
K VK-36mz

129. CAN systems
K VK-36mz

130. Economical one-wire bus
CAN data bus
Economical one-wire bus

131. 131