CAN data bus, function - GF54.00-P-0005M

MODEL 215, 220 with ENGINE 275.950

MODEL 230 with ENGINE 275.951 up to Model Year 8

MODEL 216, 221 with ENGINE 275.953 up to Model Year 8

MODEL 230 with ENGINE 275.954 up to Model Year 8

MODEL 215, 220 with ENGINE 275.980

MODEL 230 with ENGINE 275.981 up to Model Year 8

MODEL 216, 221 with ENGINE 275.982 up to Model Year 8

MODEL 240 with ENGINE 285.950

MODEL 240 with ENGINE 285.980

Shown on model 215, 220

Fig 1: Identifying CAN Data Bus Function Diagram

Courtesy of MERCEDES-BENZ USA

Data flow, model 216, 221

Fig 2: Identifying Data Flow Diagram

Courtesy of MERCEDES-BENZ USA

CAN stands for "Controller Area Network". This is an electrical bus system for carrying data over two wires.

The tasks are:

Data transfer between individual control units
Readying sensor signals for several systems
Reducing the number of electric cables
Improving electromagnetic compatibility.

The CAN data bus consists of a special twisted two-core data line that connects all CAN users (control units) in parallel.

The two lines of the data line must not be mixed up (LOW-/HIGH-level).

The data are transferred digitally over the CAN data bus at various intervals. The individual data blocks are defined in a data protocol and it is specified which data are received or transmitted by a control unit.

Each connected control unit is able to transmit or receive data (bidirectional bus). The sum of the data blocks, the short break between two transmission intervals and additional properties of the CAN data bus are checked constantly. Detected faults are stored and placed in the fault memory.

Model 215, 220, 230, 240

In the vehicle a distinction is made between a fast engine CAN data bus (CAN CLASS "C") for the drive and chassis systems and the slightly slower body CAN data bus (CAN CLASS "B") for the vehicle interior.

The interface of the two CAN data buses (Gateway) takes place on model 215, 220 in the electronic ignition switch control unit (N73), which also represents the interface between the control units on the CAN data bus and the line to the data link connector (X11/4) for STAR DIAGNOSIS. The central gateway control unit (N93) takes over these tasks in model 230 and 240.

Model 216, 221

Several CAN data bus systems are available in the vehicle. The central gateway control unit (N93) has the following tasks:

Controls the data traffic between the interior CAN, the diagnosis CAN, the chassis CAN and the central CAN.
Routing of all fault memories via the diagnosis CAN for data link connector diagnosis
Memory for production data, global variant coding (series, country version) and maintenance computer.

The ME-SFI [ME] control unit is the gateway for the drive train CAN and chassis CAN.

When a control unit is replaced, the new control unit must be coded again.

This control unit coding is via a menu of the STAR DIAGNOSIS menu.

CAN data bus, see also wiring diagrams.

ME-SFI control unit, location/task/design/function

GF07.61-P-5000M