Technical Review - Mercedes-Benz B-Class: Multiplexing

GENERAL

The CAN data bus consists of a twisted-pair data cable that connects all CAN participants (control units) in parallel. The two data bus wires must not be swapped (Low or High level). The CDI control unit always represents a terminal in the bus configuration.

For this reason, a 120 Ω terminating resistor is always fitted in the CDI control unit.

In this vehicle, a distinction must be made between the fast engine CAN data bus (CAN-C) (500 kbit/s) for the drivetrain and chassis systems, and the slower body CAN data bus (CAN-B) (83.3 kbit/s) for the interior. In addition, for external vehicle diagnosis with STAR DIAGNOSIS, there is a diagnostic CAN data bus (CAN-D) at a speed of 500 kbit/s (Fig.4).

The gateway interface of the three CAN data buses is located in the central gateway control unit.

The instrument cluster, steering column module and EZS control unit are connected to both the body CAN data bus and the engine CAN data bus, and exchange data with both bus systems. However, they do not act as a gateway between the two bus systems.

Fig. 4

DIAGNOSTIC SOCKET

The diagnostic socket is located under the dashboard, to the left of the steering column (Fig.5). It allows a diagnostic tool to be connected to the vehicle and thus communicate with all control units in the vehicle.

Stored faults can be read with STAR DIAGNOSIS or a generic scan tool.

des défauts n'est pas effacée lors de la déconnexion de la batterie du véhicule.

The fault memory is not erased when the vehicle battery is disconnected.

Diagnostic socket pin assignment (Fig.5)

Pins	Assignments
3	K-line (until May 2005)
4	Ground
5	Ground
6	CAN diagnostic high
8	Ignition-switched power supply (until May 2005)
14	CAN diagnostic low
16	Permanent power supply

Location of diagnostic socket Fig. 5

Wiring diagrams

WIRING DIAGRAM EXPLANATION

Reading wiring diagrams

Wiring diagrams

KEY

ABBREVIATIONS

ABS. Anti-lock braking system
AGW. Audio interface
APS. Navigation system
BAS. Brake Assist
CDI. Common Rail diesel injection system
EDW. Anti-theft alarm
EPC. Electronic Power Control
ESP. Electronic Stability Program
EZS. Electronic ignition and starter switch control unit
IR. Infrared
KLA. Automatic climate control
ME. ME gasoline injection and ignition system (engine electronics)
PTS. Parktronic system
SAM. Signal acquisition and actuation module
SDAR. Satellite Digital Audio Radio
WSS. Weight sensing system
ZV. Central locking

COMPONENTS

A1. Instrument cluster
A1e1. Left turn signal indicator lamp
A1e2. Right turn signal indicator lamp
A1e3. High beam indicator lamp
A1e4. Low fuel warning lamp
A1e7. Brake fluid level and parking brake warning lamp
A1e8. Instrument panel lighting
A1e9. Seat belt indicator lamp
A1e15. Airbag indicator and warning lamp
A1e16. Glow plug indicator lamp
A1e17. ABS indicator lamp
A1e26. CHECK ENGINE indicator lamp
A1e33. LIM (variable speed limiter) function indicator lamp
A1e41. ESP warning lamp
A1e43. EPC indicator lamp
A1e54. Coolant temperature warning lamp
A1e58. Engine diagnostic indicator lamp
A1h1. Buzzer
A1h2. Turn signal indicator, audible
A1p1. Coolant temperature gauge
A1p2. Fuel level gauge
A1p4. Outside temperature display
A1p5. Tachometer
A1p6. Electronic clock
A1p8. Electronic speedometer
A1p12. Engaged gear display
A1p13. Multifunction display
A1p16. Driving program display
A1r1. Instrument lighting rheostat and reset button
A1s3. Trip odometer reset button
A2. Radio
A2/6. CD changer
A2/56. Radio and navigation unit
A9. Refrigerant compressor
A26/1. IR receiver unit, front left
A26/2. IR receiver unit, front right
A40/3. COMAND control and display unit
A42. PTS sensor unit, front bumper
A42b1. Outer left sensor, front bumper
A42b3. Inner left sensor, front bumper
A42b4. Inner right sensor, front bumper
A42b6. Outer right sensor, front bumper
A43. PTS sensor unit, rear bumper
A43b7. Outer right sensor, rear bumper
A43b8. Inner right sensor, rear bumper
A43b9. Inner left sensor, rear bumper
A43b10. Outer left sensor, rear bumper
A44/1. PTS warning lamp, driver side instrument panel
A44/3. PTS warning lamp, rear roof light
B14. Temperature sensor, outside temperature display
B22/7. Rear left level sensor
B22/8. Front left level sensor
E1. Front left headlamp unit
E1e1. Left headlamp
E1e2. Left low beam
E1e3. Left position and parking light
E1e5. Left turn signal lamp
E1e9. Adaptive lighting
E1l1. High beam solenoid, left
E1m1. Left headlamp levelling motor
E1m2. Left dynamic cornering light motor
E1n1. Xenon headlamp control module
E1n2. Xenon headlamp ignition module
E2. Front right headlamp unit
E2e1. Right headlamp
E2e2. Right low beam
E2e3. Right position and parking light
E2e5. Right turn signal lamp
E2e9. Adaptive lighting
E2l1. High beam solenoid, right
E2m1. Right headlamp levelling motor
E2m2. Right dynamic cornering light motor
E2n1. Xenon headlamp control module
E2n2. Xenon headlamp ignition module
E3. Rear left light
E3/1. Rear left tailgate light
E3/1e3. Left reversing light
E3/1e5. Rear left fog lamp
E3e1. Left turn signal lamp
E3e2. Left brake light, tail light and parking light
E3e4. Left brake light
E4. Rear right light
E4/1. Rear right tailgate light
E4/1e3. Right reversing light
E4/1e5. Rear right fog lamp
E4e1. Right turn signal lamp
E4e2. Right brake light, tail light and parking light
E4e4. Right brake light
E5/1. Left fog lamp
E5/2. Right fog lamp
E6/1. Front left side marker light (USA)
E6/2. Front right side marker light (USA)
E6/5. Turn signal in left outside mirror
E6/6. Turn signal in right outside mirror
E17/3. Entry/exit light and front left door warning lamp
E17/4. Entry/exit light and front right door warning lamp
E17/5. Rear left door entry light
E17/6. Rear right door entry light
E18/1. Luggage compartment light
E21. Third brake light
E40. Proximity courtesy light, tailgate
F55/1. Fuse block 1, 9-way
F55/1f1. Fuse 1
F55/1f2. Fuse 2
F55/1f3. Fuse 3
F55/2. Fuse block 2, 9-way
F55/2f13. Fuse 13
F55/2f14. Fuse 14
F55/2f16. Fuse 16
F55/2f18. Fuse 18
F55/3. Fuse block 3, 9-way
F55/3f21. Fuse 21
F55/3f22. Fuse 22
F55/4. Fuse block 4, 9-way
F55/4f34. Fuse 34
F55/5. Fuse block 5, 9-way
F55/5f39. Fuse 39
F55/5f41. Fuse 41
F55/6. Fuse block 6, 9-way
F55/7. Fuse block 7, 9-way
F55/7f55. Fuse 55
F55/7f56. Fuse 56
F55/7f60. Fuse 60
F55/7f61. Fuse 61
F55/9. Fuse block 9
F55/9f64. Fuse 64
G1. Battery
G2. Alternator
K100. Fuse and relay box
K100kD. Rear window heater relay
K100kE. Wiper relay, speed 1/2
K100kF. Wiper relay, on/off
K100kM. Starter relay
M1. Starter motor
M3/3b1. Fuel gauge sender
M5/1. Washer fluid pump
M5/2. SRA pump
M6/1. Wiper motor
M6/4. Tailgate wiper motor
M10/3. Front left window regulator motor
M10/4. Front right window regulator motor
M10/5. Rear left window regulator motor
M10/6. Rear right window regulator motor
M14/5. Central locking motor, front right door
M14/5s1. Latch microswitch, front right door
M14/6. Central locking motor, front left door
M14/6s1. Latch microswitch, front left door
M14/7. Central locking motor, tailgate
M14/7s1. Latch microswitch, rear door
M14/8. Central locking motor, rear left door
M14/8s1. Latch microswitch, rear left door
M14/9. Central locking motor, rear right door
M14/9s1. Latch microswitch, rear right door
M14/10. Central locking motor, fuel filler flap
M21/1. Left heated power outside mirror
M21/1m1. Mirror up/down adjustment motor
M21/1m2. Mirror in/out adjustment motor
M21/1m3. Mirror folding motor
M21/1r1. Mirror heater
M21/1x1. Connector, left heated power outside mirror
M21/2. Right heated power outside mirror
M21/2m1. Mirror up/down adjustment motor
M21/2m2. Mirror in/out adjustment motor
M21/2m3. Mirror folding motor
M21/2r1. Mirror heater
M21/2x1. Connector, right heated power outside mirror
M27/1. Front left seat fore/aft adjustment motor
M27/2. Rear left seat height motor
M27/3. Front left seat height motor
M27/4. Front left head restraint motor
M27/5. Front left seat backrest recline motor
M28/1. Front right seat fore/aft adjustment motor
M28/2. Rear right seat height motor
M28/3. Front right seat height motor
M28/4. Front right head restraint motor
M28/5. Front right seat backrest recline motor
M28/6. Driver multicontour backrest motor
M28/13. Passenger multicontour backrest motor
N2/13. WSS control module (weight sensing system)
N3/9. CDI control module
N3/10. ME control module
N10. SAM control module
N14/3. Glow plug timer output stage
N15/5. Electronic selector module control unit
N22. KLA keypad
N22/7. KLA comfort keypad and control module
N26/6. EDW/anti-towing protection/volumetric protection control module
N26/9. Multifunction special vehicle control module (MSS)
N28/3. Trailer control module
N40/3. Sound system amplifier
N41/3. Speech synthesizer control module (SBS)
N47-5. ESP and BAS control module
N62. PTS control module
N68. Electric power steering (ES) control module
N69/1. Front left door control module
N69/2. Front right door control module
N69/3. Rear left door control module
N69/4. Rear right door control module
N70. Roof control unit
N73. EZS control module
N80. Steering column module
N87/5. SDAR control module
N93. Central gateway control module
N93/1. Audio gateway control module
N123/1. UHI (universal hand-held interface) support
N123/4. Emergency call system control module
R1. Heated rear window
R2/11. Washer nozzle hose heater
R3/1e1. Lighting
R3/1r1. Heating element
R3e1. Lighting
R3r1. Heating element
R9. Glow plugs
S4/1. SRA switch
S9/1. Brake light switch
S15/1. Tailgate unlock switch
S15/1e1. Left number plate light
S15/1e2. Right number plate light
S16/2. Reversing light switch
S16/5. Driving program switch
S18/7. Footwell light switch
S20/1. Switch cluster, window lifters, outside mirror adjustment and central locking, driver
S20/1s1. Front left window lifter switch
S20/1s2. Front right window lifter switch
S20/1s3. Rear left window lifter switch
S20/1s4. Rear right window lifter switch
S20/1s5. Rear side window child safety switch
S20/1s9. Outside mirror folding switch
S20/1s10. Left outside mirror adjustment switch
S20/1s11. Right outside mirror adjustment switch
S20/1s12. Rocker switch, outside mirror adjustment
S20/1s13. Interior central locking unlock switch
S20/1s14. Interior central locking lock switch
S21/2. Passenger window lifter switch
S21/2s1. Window lifter switch
S21/2s2. Central locking unlock switch
S21/2s3. Central locking lock switch
S21/3. Rear left window lifter switch
S21/4. Rear right window lifter switch
S22/1. Semi-electric seat adjustment switch, driver
S23/1. Semi-electric seat adjustment switch, passenger
S34. Radio selector
S42. Washer fluid level indicator switch
S93/3. SOS button switch
S93/6. MB-Info and telediagnosis switch cluster
S146. Pedal actuation indicator switch
U1. Valid for USA
U2. Valid for all except USA
U12. Valid for left-hand drive
U13. Valid for right-hand drive
U24. Valid for manual transmission
U29. Valid for outside temperature display
U43. Valid for EEC
U52. Valid for Japan
U144. Valid for mirror folding
U145. Valid for mirror memory
U520. Valid for taxi
U571. Valid for 4-window version
U631. Valid for version with COMAND
U656. Valid for interior lighting package
U673. Valid for KLA comfort
U679. Valid for version without xenon headlamps
U735. Valid for bi-xenon
U749. Valid for multicontour seat (MKS)
U762. Valid for MOST bus with maximum equipment
U799. Valid for door entry light
U803. Valid for dynamic cornering light
U806. Valid for IR remote control
U807. Valid for version without rear door control module
U835. Valid for engine 266
U836. Valid for engine 640
U838. Valid for CVT (continuously variable transmission)
U839. Valid for brake light switch without load
U842. Valid for intelligent washer nozzle heating
U855. Valid for AGW
U864. Valid for CD Entry Audio radio
U865. Valid for Entry Audio radio
U866. Valid for APS central unit keypad, Audio 50
W1/1. Ground, cockpit chassis
W1/2. Ground, cockpit
W3/1. Ground, front right wheel arch (ignition coil)
W3/2. Ground, front left wheel arch
W7. Ground, right luggage compartment wheel arch
W8. Ground, tailgate
W8/3. Ground, tailgate bottom
W10. Ground, battery
W11. Ground, engine (screwed cable lug)
W36. Ground, right floor
W37. Ground, left floor
X4. Cable connection, terminal 30, fuse and relay box/passenger compartment
X14/4. Connector, terminals 50, 61
X26/27. PTS connector, front bumper
X26/29. Connector, engine harness/engine compartment
X30/4. Potential distributor (CAN) connector, right
X30/7. Potential distributor (CAN) connector
X35/3. Connection block, rear left door
X35/4. Connection block, rear right door
X35/28. PTS connector, rear bumper
Z36/1. Ground terminal sleeve, rear PTS sensors
Z36/2. Power supply terminal sleeve, rear PTS sensors
Z36/3. Ground terminal sleeve, front PTS sensors
Z36/4. Power supply terminal sleeve, front PTS sensors
X39/37. Mobile phone connection block
X55/3. Driver seat connection bar
X55/4. Passenger seat connection bar
X63/4. CAN data bus connector, 2-pin
X88/2. Wiper motor/third brake light connector
Y3/9. CVT (continuously variable transmission) electric control unit
Y3/9n1. CVT (continuously variable transmission) control module
Z3/31. Protected terminal 15R sleeve, sidebag
Z3/60. Driver terminal 15R sleeve
Z5. Terminal sleeve (welded connection in harness)
Z6/1. Ground terminal sleeve
Z6/8. Sensor ground terminal sleeve
Z6/94. Driver seat terminal 31 sleeve
Z6/95. Passenger seat terminal 31 sleeve
Z7/5. Terminal 87 sleeve
Z7/36. Terminal 87 M2e sleeve
Z7/41. Sensor power supply terminal sleeve
Z35/10. MOST wake-up signal terminal sleeve
Z81. Terminal 58d sleeve