Controller Area Network
CAN
507 HO CAN B (ICC)10-28-02
1
These technical training materials are current as of the date noted on the materials, and may be revised or updated without notice.
Always check for revised or updated information.
To help avoid personal injury to you or others, and to avoid damage to the vehicle on which you are working, you must always refer
to the latest Mercedes-Benz Technical Publication and follow all pertinent instructions when testing, diagnosing or making repair.
Illustrations and descriptions in this training reference are based on preliminary information and may not correspond to the final US
version vehicles. Refer to the official introduction manual and WIS when available.
Copyright Mercedes-Benz USA, LLC, 2002
Reproduction by any means or by any information storage and retrieval system or translation in whole or part is not permitted
without written authorization from Mercedes-Benz USA, LLC or it's successors.
Published by Mercedes-Benz USA, LLC
Printed in U. S.A.
2
Objectives
• Explain advantages of CAN networks
• Explain how CAN networks operate
• Describe location of CAN connectors
• Explain CAN diagnosis techniques
• Provide reference information on other models
(reference section at back of handout)
3
What is a CAN System?
A CAN system is:
• A digital communication link between multiple
Electronic Control Modules (ECM)
• A 2 wire, bi-directional communication link with data
transmitted according to priority
• Message specific addressing
4
Advantages
• Cost
• Improved immunity to electrical interference
• Fewer connectors
• Fewer pins on control modules
• Weight savings
• Fewer sensors
• Improved diagnosis facilities
• Rapid transmission rates
5
Types of CAN Communication
Mercedes-Benz uses several CAN networks. Depending
on model and year the following may be used.
CAN C - Engine CAN (also known as chassis CAN)
Fast communication speeds 125 kbps or 500 kbps
CAN B - Interior CAN (also known as body CAN)
Communication speed 83 kbps
Information from CAN C can be sent to control modules
on the CAN B or vice versa via the Electronic Ignition
Switch (EIS). The EIS is the only control module* that
can transfer the messages and is known as the
gateway.
6
Without CAN
Coolant sensor 1
Control module 1
(e.g. fuel system)
Coolant sensor 2
Coolant sensor 3
Control module 2
(e.g. climate control)
Control module 3
(e.g. ignition)
7
CAN Bus
Sensor 1
Control
module 2
Control module 1
Control
module 3
Control
module 4
Control
module 5
Control
module 6
8
CAN B Example
Controlling R.R. window from L.F. door
window switch
window switch
RR DCM
RF DCM
window switch
LR DCM
window switch
LF DCM
CAN High & Low
The CAN wiring consist of 2 wires called CAN High
(CAN H) and CAN Low (CAN L).
All the control modules are connected in a parallel circuit
using either Z splices or plug connector blocks (X30/_).
For the remainder of this presentation and shop
modules, we will concentrate on the CAN B network as
used in W203 / W220).
10
CAN H
• CAN-H has a voltage of approx. 0.025 volts when dormant
• Rises to base voltage of 0.65 volts when communicating
• Data seen as voltage levels going “high”
~0.65volt
~0.025volt
11
CAN L
• CAN-L has a voltage of 11.0 volts dormant
• Base voltage drops to 4.65 volts when active
• Data seen as voltage level going “low”
~11 volt
~4.65 volt
12
CAN B High & Low
~11volt
~4.65volt
~0.65volt
~0.025volt
13
Safety Concept
CAN L still communicates (single line operation)
CAN H shorted to ground, cannot communicate
14
Wake-up Signal
Door switch
Rear SAM
EIS
z...z…z…z…z...
WAKE UP !! / Door open
• EIS is the master of the CAN
• EIS wakes up the control
modules on the CAN
N70 (Overhead Control Panel)
15
Tools For Diagnosing CAN B
h Ohm meter
h Volt meter
h Oscilloscope
h CAN B test harness
h SDS
220 589 00 99 30
h WIS
Note: The red lead is not always the CAN H
16
W203 CAN B (MY 2001)
via N10/1
N73
N70
N22
A1
N72/1
Note: Always refer to the wiring
diagram for your model
and year.
N10/1
X30/4
N69/4
X30/6
N69/2
N32/2
X30/7
2
1
N10/2
A40/3
N32/1
N69/1
N2/7
A35/17
N69/3
1 early
late
2
GN/WT
GN
RD
BN
BN/BK
BN
CAN H wires are BN/RD
CAN L wires are BN
except where indicated
17
W203 CAN B Connector X30/6
h N73
- EIS
h N72/1 - UCP
h A1
- ICM
h N22
- AAC
h N70
- OCP
h N10/1 - Front SAM
18
W203 CAN B Connector X30/7
h N10/1 - Front SAM
h A40/3 - COMAND
h A2
- Radio
h N69/1 - DCM-FL
h N69/3 - DCM-RL
h N10/2 - Rear SAM
h N32/1 - ESA-FL
19
W203 CAN B Connector X30/4
h N69/2 - DCM-FR
h N69/4 - DCM-RR
h N2/7
- SRS
h A35/17 - TELE AID
h N32/2 - ESA-FR
20
CAN B Malfunctions
h Shorted CAN B
h Constantly active CAN B
h Incorrect version coding
21
Shorted CAN B
When both the High and Low CAN B are shorted to ground or
positive no communication is possible between control units.
This can happen if:
a. Control unit shorted
b. Wiring harness shorted
How could we determine if the CAN B is shorted?
a. Monitor CAN B voltage out of EIS
b. Monitor CAN B oscilloscope pattern out of EIS
c. Monitor the DAS (SDS)
22
Constantly Active CAN B
CAN B needs to go into a dormant state when the ignition
switch is in the 0 position. EIS is the control unit in charge of
activation and deactivation of the CAN B.
If a control unit in the CAN B keeps sending a signal the EIS
will not request the CAN B to go into a dormant state.
How can we determine if the CAN B has not gone into a
dormant state?
a. Monitor CAN B activity with an oscilloscope
b. Monitor CAN B voltage
23
Diagnostic Exercise For CAN B
The following diagnostic exercise involves a
W203 with a shorted control unit.
24
W203 CAN B
N73
N70
N22
A1
N72/1
N10/1
X30/4
X30/6 (dash)
N69/4
N69/2
X30/7 (left)
N32/2
N2/7
N10/2
A40/3
N32/1
N69/1
N69/3
A35/17
25
Diagnostic Exercise For CAN B
26
N73
N70
N22
A1
N72/1
N10/1
X30/4
X30/6
N69/4
N69/2
X30/7
N32/2
N2/7
N10/2
A40/3
N32/1
N69/1
N69/3
A35/17
27
N73
N70
N22
A1
N72/1
N10/1
X30/4
X30/6
Disconnect CAN wire
N69/4
N69/2
X30/7
N32/2
N2/7
N10/2
A40/3
N32/1
N69/1
N69/3
A35/17
28
N73
N70
N22
A1
N72/1
N10/1
X30/4
X30/6
Disconnect CAN wire
Re-connect CAN wire
X30/7
N69/4
N69/2
N32/2
N2/7
N10/2
A40/3
N32/1
N69/1
N69/3
A35/17
Re-connect CAN wires until network instable again
29
N73
N70
N22
A1
N72/1
N10/1
X30/4
X30/6
N69/4
N69/2
X30/7
N32/2
N2/7
N10/2
A40/3
N32/1
N69/1
N69/3
A35/17
30
N73
N70
N22
A1
N72/1
N10/1
X30/4
X30/6
N69/4
N69/2
X30/7
N32/2
N2/7
N10/2
A40/3
N32/1
N69/1
N69/3
A35/17
31
Diagnostic Exercise For CAN B
Press the F2 key for a list of control units that the EIS can
communicate with
32
Diagnostic Exercise For CAN B
33
Reference Materials for Further
Reading
WIS documents :
GF00.19-P-0001PP
SN00.19-P-0004GH
GF54.00-P-0004A
GF54.00-P-0005A
GF54.00-P-0005-01A
GF54.00-P-0005-02A
GF54.00-P-0005-04A
GF54.00-P-0999ZZ
Extended vehicle network function
Complete networking (163 as of 9/01)
Data bus system function
CAN data bus, function
CAN data bus data telegram
CAN data bus specification
CAN data bus applications
CAN data bus, contents, function description
34
Additional Information for
Other Models
35
CAN B Voltages W203, C215 & W220
h CAN H active: 0.65V, dormant: 0.025V
h CAN L active: 4.65V, dormant: 11.0V
CAN B Voltages W202, C208 & W210
h CAN H active: 1.8V, dormant 0.025V
h CAN L active: 3.2V, dormant 4.8V
36
CAN B on W203 with connector X35/2
(Vehicles from approx. 06/02)
N73
N70
N22
A1
N72/1
Note: Always refer to the wiring
diagram for your model
and year.
N10/1
Brown and
Brown with
Red tracer
X30/6
N69/2
X30/4
N69/4
X35/2
N32/2
X30/7
N2/7
N10/2
A40/3
N32/1
N69/1
N69/3
A35/17
37
X35/2
Location: Right front sill
38
W220 CAN B
N73
N80
N22
A1
N72/1
N10/7
X30/6
Green Band
W
White Band
Y
Yellow Band
N10/6
N70
W
G
G
X30/4
W
N10/8
N69/4
X30/5
Y
N69/2
N62
N32/2
A37
A40/3
N22/4
N32/1
N69/1
N69/3
N25/6
N69/5
N88
39
C215 CAN B
N73
N80
N22
A1
N72/1
N10/7
X30/6
Green Band
W
White Band
Y
Yellow Band
N10/6
N70
W
G
G
X30/4
W
N10/8
N69/5
X30/5
Y
N62
N22/6
N32/2
A37
A40/3
N32/1
N69/1
N88
N69/2
40
Location of X30’s for C215 & W220
X30/6
X30/4
X30/5
41
C215 / W220 Connector X30/6
white band
green band
h Wires with the green band go
to N73 (EIS)
h Wires with the white band go
to N10/6 (Left SAM)
42
C215 / W220 Connector X30/5
h Wires with the white band go
to N10/6 (Left SAM)
yellow band
h Wires with the yellow band
go to X30/4
white band
43
Control Units Connected to X30/6
C215 / W220
h N73
- Electronic Ignition Switch
h N80
- Steering Column Module
h N22
- Automatic Air Conditioning
h A1
- Instrument Cluster
h N72/1 - Upper Control Panel
h N10/7 - Right SAM
h N10/6 - Left SAM
44
Control Units Connected to X30/5
C215 / W220
h A37
- PSE
h A40/3 - COMAND
h N22/4 - Rear automatic air conditioning
h N32/1 - Electric seat adjustment left
h N69/1 - Door control module 1
h N69/3 - Door control module 2
h N10/6 - Left SAM
45
Control Units Connected to X30/4
C215 / W220
h N10/8 - Rear SAM
h N70
- Overhead control panel (Via N10/8)
h N69/2 - Door control module 2
h N69/4 - Door control module 4
h N62
- Parktronics
h N32/2 - Electric seat adjustment right
h N25/6 - Electric seat adjustment rear
h N88
- Tire pressure monitoring
h N69/5 - KeyLess Go
46
W202, 208, 210 CAN B
• Electronic Ignition Switch
EIS - N73
• Signal Acquisition and Actuation Module
SAM - N10/1
• Door Control Modules
DCM’s - 1 for each door N69/1-4
• Pneumatic System Equipment
PSE - A37
• Electronic Seat Adjustment
ESA’s - N32/1&2
• Overhead Control Panel
OCP - N70
• Lower Control Panel
LCP - N72
X30/7 - Right front door sill
47
W210 CAN B
R.R.door
48
W202, 208 & 210 CAN B
5V
CAN LOW
Low Sleep Voltage 4.8V
4V
3V
2V
(CAN Message)
(CAN Message)
Low Awake Voltage 3.2V
High Awake Voltage 1.8V
1V
CAN HI
High Sleep Voltage 0.2V
0V
49
G Class (463) Networking
Interior
Engine
Not on CAN BUS
N25/6, Rear seat heater
module
N30/2, Differential lock
module
50
CAN B Diagram for 463
N73
N69/1
A1
A35/11
All CAN H wires are red
All CAN L wires are brown
except where noted
X30/4
N72/1
X30/6
N69/4
CAN H wire black
CAN L wire brown
X30/7
N69/2
N32/2
N22
N10/2
A40/3
N32/1
N69/3
N10/1
N70
51
463 CAN B Connector Locations
X30/6 under drivers dash
X30/4 and X30/7 in passenger
kick panel
CAN wires are labeled with a tag on
X30/4 & X30/7
52
463 CAN C Connector
X63/4
Location: Right side of center console
53
R230 CAN B , CAN C & D2B
CAN- C
Gn
Gn/Wh
N15/5
ESM
N15/3
ETC
N47-5
ESP
2-wire
SBC CAN
A73n1
SBC
A1
ICM
N80
SCM
N69/1
DCM-L
N10/10
SAM-FL
N22
AAC
N72
LCP
N32/1
ESA-L
X11/4
X30/15
CAN- B
N51/2
ABC
N35/15
MCS-L
N73
EIS
CAN- B
N63/1
DTR
X30/18
N3/10
ECM
A35/16
MCS-R
Br
Br / Bk
CAN- B
Br
Br / Bk
N70
OCP
N69/2
DCM-R
N55
SD
N2/7
SRS
D2B
N52
RVC
N10/8
Rear SAM
N62
PTS
N88
TPC
N69/5
KG
N82/1
BNS
A35/8
Tele Aid
A2
COMAND
A37
PSE
CAN B
wire colors
(except
where noted)
Br
Br / Rd
X30/17
CAN C
N32/2
ESA-R
X30/16
N10/11
SAM-FR
CAN B
not connected to either CAN
54
R230 CAN B Connector X30/15
Inside driver’s side door sill
(next to X30/18)
EIS (N73)
IC (A1)
SCM (N80)
DCM-L (N69/1)
X3
0/1
SAM-FL (N10/10)
5
AAC (N22)
LCP (N72)
ESA-L (N32/1)
MCS-L (N35/15)
55
R230 CAN B Connector X30/16
Inside passenger side door sill
SAM-FR (N10/11)
OCP (N70)
X
16
30/
DCM-R (N69/2)
SD (N55)
ESA-R (N32/2)
MCS-R (A35/16)
56
R230 CAN B Connector X30/17
Behind passenger seat, next to SAM
RVC (N52)
SAM-Rear (N10/8)
PTS (N62)
/17
0
X3
TPC (N88)
KG (N69/5)
BNS (N82/1)
TELE AID (A35/8)
COMAND (A2)
D2B
PSE (A37)
57
R230 CAN C Connector X30/18
Inside driver’s side door sill
(next to X30/15)
EIS (N73)
IC (A1)
X3
0/1
SCM (N80)
8
ECM (N3/10)
DTR (N63/1)
ABC (N5/12)
ESM (N15/5)
ETC (N15/3)
ESP (N47-5)
SBC (A73n1)
58
W211 Networking Diagram
X11/4
N3/10
N15/5
N15/3
N51
N71
N63/1
N93
X30/5
CAN C
N47/5
CAN D
N93
CAN B
A1
N73
N22
N99
N10/1
N112
X30/6
N80
N112 - Communication
Platform (TeleAid)
N69/1
X30/4
N25/7
N32/1
N69/2
N69/4
N70
N72
N32/19
N10/11
CAN B
N69/3
LCP if vehicle
equipped with
DTR / SAS
N82
N2/7
N72/1
N62
N88
N121
N93/1
M40/1
N10/2
CAN B
X30/7
MOST
N32/2
N32/22
CAN B
CAN C
CAN D
MOST
Interior bus
Engine bus
Diagnosis bus
Audio Bus
59
W211 Networking Legend
CAN C
N32/19 Left Front Dynamic Seat Control
N3/10
ME-SFI Control Module
N32/22 Right Front Dynamic Seat Control
N15/3
ETC - Electronic Transmission Control
N62
PTS - Parktronic Control
N15/5
ESM - Electronic Selector Module
N69/1
DCM - Left Front Door Control Module
N47/5
ESP - Electronic Stability Program
N69/2
DCM - Right Front Door Control Module
N51
SAS - Semi-Active Air Suspension
N69/3
DCM - Left Rear Door Control Module
N63/1
DTR - Distronic Control Module
N69/4
DCM - Right Rear Door Control Module
N71
HRA - Headlamp Range Adjustment
N70
OCP - Overhead Control Panel
N93
CGW - Central Gateway Module
N72/1
UCP - Upper Control Panel
N82
BCM - Battery Control Module
CAN B
M40/1
Pneumatic Pump of Dynamic Seat
N88
TPC - Tire Pressure Monitor Control Module
N2/7
Supplemental Restraint System
N93/1
AGW - Audio Gateway Control Module
N10/1
SAM-D - Driver-side
N99
SWH - Steering Wheel Heater
N10/2
SAM-R - Rear
N121
RTL - Remote Trunk Locking Control Module
N10/11 SAM-P - Passenger-side
CAN C & B
N22
AAC - Automatic Air Conditioning Control
A1
ICM - Instrument Cluster
N25/7
HS and Seat Ventilation Control Module
N73
EIS - Electronic Ignition Switch Control
N32/1
ESA - Left Front Seat Adjustment
N80
SCM - Steering Column Module
N32/2
ESA - Right Front Seat Adjustment
N93
CGM - Central Gateway Module
60
CAN C Connector (X30/5)
Location: Drivers rocker panel wiring trough
61
CAN B Connector (X30/4)
Location: Right side passenger footwell
62
CAN B Connector (X30/6)
Location: Passenger side HVAC case
63
CAN B Connector (X30/7)
Location: Drivers rocker panel wiring trough
64
SAM-Rear (N10/2)
Several control modules
are connected to the CAN B
network via N10/2.
Location: Left side trunk
65
W211 CAN D
• Is the diagnostic link between
Central Gateway Module
(N93), Communications
Platform (N112) and SDS /
DAS
CAN Low - Pin 14 (GN)
CAN High - Pin 6 (GN/WT)
CAN Low
• CAN D voltage
High = 2.5v
Low = 2.5v
• CAN D voltage awake
High = activity to 3.5v
Low = activity to 1.5v
• All modules on CAN B are
diagnosed by SDS / DAS
through CAN D
X11/4
9
16
1
8
CAN High
N93
N112
66