Mercedes Benz 204 Interior CAN Control Units

· 1 Electronic ignition lock control unit
· 2 Left front door control unit
· 3 Right front door control unit
· 4 Left rear door control unit
· 5 Right rear door control unit
· 6 Driver seat control unit
· 7 Front passenger seat control unit
· 8 Overhead control panel control unit
· 9 Front SAM control unit with fuse and relay module
· 10 Rear SAM control unit with fuse and relay module
· 11 Tire pressure monitor control unit (USA only)
· 12 Trailer recognition control unit
· 13 PARKTRONIC control unit
· 14 KEYLESS-GO control unit
· 15 Automatic air conditioning control and operating unit
· 16 Instrument cluster
· 17 Special-purpose vehicle multifunction control unit
· 18 COMAND controller unit.
· 19 Weight Sensing System (WSS) control unit (I only)
· 20 Panoramic sliding roof control module
· 1 Electronic ignition lock control unit
· 9 Front SAM control unit with fuse and relay module
· 16 Instrument cluster
· 21 ME-SFI [ME] control unit (gasoline engines)
· 22 CDI control unit (diesel engines)
· 23 Electronic Stability Program control unit
· 24 Steering column module control unit
· 25 Supplemental restraint system control unit
· 26 Left front reversible emergency tensioning retractor
· 27 Right front reversible emergency tensioning retractor
· 28 Adaptive damping system control unit
· 23 Electronic Stability Program control unit
· 29 Yaw rate, lateral and longitudinal acceleration sensor
· 21 ME-SFI [ME] control unit (gasoline engines)
· 22 CDI control unit (diesel engines)
· 30 Electronic selector lever module control unit
· 31 Fully integrated transmission control controller unit
· 32 Fuel pump control unit (gasoline engines)
· 33 Electronic transmission control unit
· 18 COMAND controller unit
· 34 Sound system amplifier control unit
· 35 Digital Radio Broadcasting control unit
· 36 Satellite digital audio radio (SDAR) control unit (USA only)
· 18 COMAND controller unit
· 37 Audio/COMAND display
· 38 Audio/COMAND control panel
· 9 Front SAM control unit with fuse and relay module
· 39 Emergency call system control unit (USA only)
· 9 Front SAM control unit with fuse and relay module
· 40 Left xenon lamp control unit
· 41 Right xenon light control unit
Instrument panel LIN
· 9 Front SAM control unit with fuse and relay module
Wiper/inside rearview mirror LIN
· 9 Front SAM control unit with fuse and relay module
Front door LIN
· 2 Left front door control unit
· 3 Right front door control unit
Rear SAM LIN
· 10 Rear SAM control unit with fuse and relay module
On-board electrical system LIN
· 10 Rear SAM control unit with fuse and relay module
Climate control LIN
· 15 Automatic air conditioning control and operating unit
· 42 Rear automatic air conditioning operating unit
Drivetrain LIN
· 21 ME-SFI [ME] control unit (gasoline engines)
· 22 CDI control unit (diesel engines)
Steering LIN
· 24 Steering column module control unit
Note
The illustration of the overall network shows a vehicle with all the available special equipment.
The network architecture in model series 204 has been completely redesigned from that of the predecessor model series. The number of sub-networks in which the individual electronic control units are grouped has been significantly increased. The new architecture in model series 204 is a logical development of the electrical and electronic systems architecture of model series 221. With the focus on reducing complexity, the individual control units are grouped together in more function-related sub-networks than before in order to achieve greater reliability of the overall system coupled with lower manufacturing costs.
The main features of the new network architecture include:
• Finer structuring of the CAN network
• The linking between the CAN sub-networks via several control units with integral gateway functions
• The use of numerous sub-bus systems in the form of single-wire local interconnect network (LIN) buses
• Front SAM control unit with fuse and relay module with central gateway function
• ME-SFI [ME] control unit (gasoline engine) CDI control unit (diesel engine)
• Special-purpose vehicle multifunction control unit
• Audio/COMAND control panel
One innovation is the integration of the central gateway with the front SAM control unit with fuse and relay module in a single housing. Both control units feature separate microprocessors, each with a dedicated CAN interface.
The front SAM control unit with fuse and relay module therefore has direct access to the interior CAN.
A total of six bus systems are linked together over the integrated central gateway.
These also include the diagnostic CAN, which links the diagnosis test system with the other sub-networks.
The diagnostic CAN is the sole diagnosis communications interface between the external diagnosis test system and the vehicle. It offers the advantages of a high data transfer rate of 500 kBit/s, compared to the 10.4 k Baud K-lines previously used, and the capability of parallel diagnosis of control units. The vehicle therefore satisfies the legal requirements for exhaust gas diagnosis that approve the diagnostic CAN as a new interface since 2003 (EU & USA) and will prohibit any other interfaces from 2008 onwards (USA).
All CAN and MOST control units have diagnosis capability.
LIN components are diagnosed through their associated master control units. Each control unit has its own internal fault memory.
The supreme goal of on-board electrical system management is to assure a positive charge balance in the battery in order to guarantee that the vehicle can be started.
The load state of the on-board electrical system is determined from the characteristic variables available in the vehicle, and suitable measures are initiated as and when necessary. These include, for example, specifying different charging voltages for the alternator, increasing the rpm at engine idle and, as a last resort, reducing the power of individual convenience systems.
To allow the vehicle to remain idle for long periods, the load on the battery from the quiescent current must be as low as possible. Besides optimization of the individual components, two further measures have been implemented:
· Decentralized power management and a quiescent current switch.
· Decentralized power management is integrated in all control units as a standard software module and prevents undesirable control unit activity when the vehicle is parked. The quiescent current switch is a bistable relay that is opened by the on-board electrical system management when the vehicle is idle and the run-on time has elapsed. All control units that are not required when the car is parked are disconnected from the battery, further minimizing the quiescent current demand.
The maintenance interval display and service processor functions are integrated in the instrument cluster.
The maintenance interval display computes the remaining time and remaining distance of the engine oil and triggers oil warnings.
The service processor takes the calculated values from the maintenance interval display and shows the next service date and other dates for due maintenance operation on the display in the instrument cluster. The remaining distance and remaining time are displayed.
It also shows whether a major or minor service is due and the scope of any necessary additional operations.

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