WIS 54.21 Control Units/Modules

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

EIS (EZS) Electronic Ignition Switch Control Module

Refer to WIS 80.57 Drive Authorization System

ESCM (MAS) Engine Systems Control Module

TBA

SCM (MRM) Steering Column Module

TBA

Fault Error Codes/Diagnostic Trouble Codes (DTC)

DTC Structure

DTC Example

P0420 Catalyst System Efficiency Below Threshold (Bank 1)

• 1st digit: (P) Indicates which system reported the fault.
  • B = Body,
  • C = Chassis,
  • P = Powertrain,
  • U = Network eg CAN
• 2nd digit (0) Indicated type of fault code.
  • 0 = Standardized eg OBD Code
  • 1 = Manufacturer Code
• 3rd digit (4) Indicated the assembly where the fault occurred.
  • 1 = Fuel and airflow monitoring
  • 2 = Injection nozzles
  • 3 = Ignition system and combustion misfiring
  • 4 = Additional systems for emissions reduction
  • 5 = Idle and vehicle speed
  • 6 = Onboard computer and other outputs
  • 7 = Transmission
  • 8 = Transmission
• 4th digit (20) Indicated faulty component and type of fault.

List of DTC

Downloadable pdf files.

http://www.benzworld.org/forums/w220-s-class/1639927-guide-mercedes-benz-vehicle-data-card.html