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ECO Start/Stop Function Engine Management, Function - GF07.10-P-1042MRD

Engine 274.9 in model 213 (except 213.050/053/153), 238 

up to model year 2021 

IMPORTANT The ECO start/stop function is subdivided into the engine-side and the on-board network side scope.

This function is seen from the point of view of the engine management.

Function requirements, general 

IMPORTANT The ME-SFI [ME] control unit (N3/10) detects engine running via the evaluation of the crankshaft Hall sensor signals (B70). The ME-SFI [ME] control unit directly reads in the signals of the crankshaft Hall sensor.

IMPORTANT The front SAM control unit (N10/6) transmits the outside temperature via the interior CAN (CAN B), electronic ignition lock control unit (N73), suspension FlexRay (Flex E), powertrain control unit (N127) and drive CAN (CAN C1) to the ME-SFI [ME] control unit.

Engine management ECO start/stop function 

For a stationary vehicle, the ECO start/stop function switches the engine off automatically and starts it again as soon as the driver wishes to drive off or the system requests engine running. The fuel consumption and thus the exhaust emissions are reduced by cutting out the engine with the vehicle at a standstill.

It is still possible to stop and start the engine in the conventional way. The powertrain control unit permanently performs a system diagnosis and evaluates the system statuses for the ECO start/stop function. All active systems that may be impaired by a shutoff engine constantly check their status. Once the status of a system permits an engine stop, this transmits its enable to the powertrain control unit.

The operational readiness of the ECO start/stop function is shown to the driver by the "ECO" symbol in the instrument cluster (A1).

The powertrain control unit transmits the request to activate the "ECO" symbol via the suspension FlexRay, electronic ignition lock control unit and user interface CAN (CAN HMI) to the instrument cluster.

The ECO start/stop function is activated and deactivated via the ECO start/stop function button (N72/4s3) in the left lower control panel (N72/4). The left lower control panel directly reads in the ECO start/stop function button and transmits the signals via the LCP-LIN (LIN A3), audio/COMAND control panel (A40/9) (except code 446 (Touchpad only)) or touchpad (A105) (with code 446 (Touchpad only)), telematics CAN (CAN A), head unit (A26/7), user interface CAN, electronic ignition lock control unit and suspension FlexRay to the powertrain control unit.

The ECO start/stop function contains the following subfunctions:

Automatic engine stop 

The engine is shut off, if all the following requirements are fulfilled:

The front SAM control unit transmits the status of the 12 V on-board electrical system via the interior CAN, electronic ignition lock control unit and suspension FlexRay to the powertrain control unit.

IMPORTANT The powertrain control unit transmits the enable for engine stop via the drive CAN to the ME-SFI [ME] control unit. The ME-SFI [ME] control unit transmits the status via the drive CAN to the powertrain control unit.

IMPORTANT After an automatic engine stop a maximum of three automatic engine stops are permitted without exceeding the speed threshold of 8 km/h.

After the fourth engine start, the vehicle must exceed a speed of 8 km/h for the engine to be stopped again.

Upon opening the engine hood in automatic engine stop, the ECO start/stop function is switched off and all indicator symbols in the instrument cluster light up.

The engine must then be restarted by the driver.

IMPORTANT A warning tone is output if the engine was shut off by the ECO start/stop function and the driver exits the vehicle. The display message "Veh. is operational, switch off ignition before exiting vehicle" also appears in the multifunction display. If the ignition is not switched off, the ignition is automatically switched off after a minute.

Automatic engine start 

The engine is automatically started if the driver:

IMPORTANT A maneuvering process is recognized for an engaged reverse gear and the ECO start/stop function is deactivated. If the engine is stopped it is force started by the system and the engine stop function is suppressed if it is running. The ECO start/stop function is subsequently activated again for an engaged gear range D and for exceeding a vehicle speed of 15 km/h.

Forced engine start (start dictated by the system) 

To ensure the on-board electrical system stability and the function of the safety-relevant systems, the engine can be force started by the system.

The engine is started if the on-board electrical system is, for example, loaded by load intensive consumers or a function or stop requirement is no longer fulfilled.

If the on-board electrical system stability can subsequently still not be ensured, the ECO start/stop function is switched off and the engine is no longer shut off.

The following events also lead to a forced engine start:

  Electrical function schematic for engine management, ECO start/stop function   PE07.10-P-2724-97DBD
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