WIS 54.21 Control Units/Modules

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Description - Control Units/Modules

The W220 has a host of Control Units/Modules also known as Electronic Control Modules (ECM) which communicate digitally with each other via the CAN (Controller Area Network) Bus.

Information from CAN C - Engine CAN can be sent to control modules on the CAN B - Interior CAN 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.

All the Control Units/Modules are connected in a parallel circuit via a two wire, bi-directional communication link (the Bus) with data transmitted according to priority.

The Control Units/Modules have been designed with in-built monitoring functions which whenever parameters exceed acceptable limits will produce Warning Messages on the Instrument Cluster and store relevant Fault Error Codes or Diagnostic Trouble Codes (DTC) in the vehicle memory. These DTC may be monitored using the [STAR] Diagnosis System (SDS). In addition to On-Board Diagnosis (OBD) STAR can perform comprehensive system diagnosis on all vehicle systems via the Control Units/Modules for engine control, suspension, audio systems, climate control etc.

Types of Control Units/Modules:

  • CCM Multi-function Control Module
  • DAM (FBM) Drive Authorization Module
  • DCM Door Control Module
  • EIS (EZS) Electronic Ignition Switch Control Module
  • ESCM (MAS) Engine Systems Control Module
  • ESM (EWM) Electronic Selector Lever Module
  • GRM (GEM) Gear Recognition Module
  • SAM Signal Acquisition / Actuation Module
  • SCM (MRM) Steering Column Module
  • SIM Subscriber Identification Module
  • SVCM (MSS) Special Vehicle Multi-function Control Module

Location Diagram - Control Units/Modules


Reference: http://www.benzworld.org/forums/w220-s-class/1573152-esp-module-where.html

DCM Door Control Module

EIS (EZS) Electronic Ignition Switch Control Module

Refer to WIS 80.57 Drive Authorization System

ESCM (MAS) Engine Systems Control Module


SAM (Signal Acquisition / Actuation Module)

SCM (MRM) Steering Column Module



Fault Error Codes/Diagnostic Trouble Codes (DTC)

A list of the Mercedes-Benz Fault Error Codes/Diagnostic Trouble Codes (DTC) for 1996+ models is here M-B Fault Error Codes/Diagnostic Trouble Codes (DTC)

Vehicle Data Card or SA Codes

The Vehicle Data Card is a small card that lists important information such as the options fitted, serial numbers, delivery dates, key codes to cut new keys etc. See here Data Card

Automatic Climate Control Hidden Menu Codes

To access/review/read and clear/reset Fault/Error Diagnostic Trouble Codes (DTC) associated with the ACC see here Automatic Climate Control (ACC) Service Menus


To see information about COMAND Codes see here WIS 82.85 Navigation and Communication System (CNS, ICS, COMAND, FleetBoa) A40/3