E320 1999

Electronic Control Module



Click image to see an enlarged view

Fig. ECM location


The powertrain has electronic controls to reduce exhaust emissions while maintaining excellent driveability and fuel economy. The Motor Electronic Control Unit is the control center of this system. The ME engine controller monitors numerous engine and vehicle functions. The DME engine controller constantly monitors the information from various sensors and other inputs, and controls the systems that affect vehicle performance and emissions.

The ME engine controller also performs the diagnostic tests on various parts of the system. The ME engine controller can recognize operational problems and alert the driver via the Malfunction Indicator Lamp (MIL). When the ME engine controller detects a malfunction, it stores a Diagnostic Trouble Code (DTC). The problem area is identified by the particular DTC that is set. The control module supplies a buffered voltage to various sensors and switches. Review the components and wiring diagrams in order to determine which systems are controlled by the ME engine controller.

Removal & Installation

M112 And M113 Engines
  1. Before servicing the vehicle, refer to the precautions.
  3. Remove air filter housing.
  5. Move shift interlocks for electrical connectors on control unit outward and remove electrical connectors from ME control unit.
  7. Pull out control unit upwards out of right control unit bracket and left control unit bracket.
  9. Detach ball-type support braces from control unit.
  11. Detach right control unit bracket and left control unit bracket as required from resonance intake manifold.

    Click image to see an enlarged view

    Fig. ECM location


To install:

  1. Installation is the reverse of removal.
  3. Tighten control unit holder to resonance intake manifold bolt to 6 ft. lbs. (8 Nm).
  5. Tighten ball head support to control unit to 3 ft. lbs. (4 Nm).
  7. When replacing the control unit, perform the following using Star Diagnosis or equivalent scan tool.

    Sensor rotor adaptation
    Release the transport protection on control unit
    Personalize and activate the control unit



All Mercedes Benz electronic testing is performed by reading the fault memory of ME control unit and if necessary, working through test schedules contained in the Star Diagnosis tool.