ECO Start/Stop Function Engine Management, Function - GF07.10-P-1042MRT
Engine 256.9 in model 213, 238, 257, 290
up to model year 2021
Engine 256.9 in model 222
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
- Engine runs
- Outside temperature -10 to 40°C
- System diagnosis complete and fault-free
- One-time exceeding of 8 km/h for forward travel
- No brake assist system control intervention function
The ME-SFI [ME] control unit (N3/10) detects the 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.
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. As soon as the status of a system permits an engine stop, it transmits its release 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.
Model 222
The ECO start/stop function is switched on or off using the ECO start/stop function button (N72s9) in the lower control panel (N72) (with code 446 (Touchpad only)) or the ECO start/stop function button (A40/9s9) in the Audio/COMAND control panel (A40/9) (with code 448 (Touchpad)).
The lower control panel (with code 446 (Touchpad only)) transmits the status of the ECO start/stop function button via the LCP-LIN (LIN A3), touchpad (A105), telematics CAN (CAN A), head unit (A26/17), user interface CAN, electronic ignition lock control unit, and suspension FlexRay to the powertrain control unit.
The Audio/COMAND control panel (with code 448 (Touchpad)) transmits the status of the ECO start/stop function button via the telematics CAN, head unit, user interface CAN, electronic ignition lock control unit, and suspension FlexRay to the powertrain control unit.
Models 213, 238, 257
The ECO start/stop function is switched on or off using the ECO start/stop function button (N72/4s3) in the left lower control panel.
The lower control panel transmits the status of the ECO start/stop function button via the LCP-LIN, Audio/COMAND control panel (except code 446 (Touchpad only)) or touchpad (with code 446 (Touchpad only)), telematics CAN, head unit, user interface CAN, electronic ignition lock control unit, and suspension FlexRay to the powertrain control unit.
The ECO start/stop function is described in the following points:
- Automatic engine stop
- Automatic engine start
- Forced engine start (start dictated by the system)
Automatic engine stop
The engine is shut off, if all the following requirements are fulfilled:
- ECO start/stop function activated
- Vehicle speed 0 km/h
The instrument cluster transmits the vehicle speed via the user interface CAN, electronic ignition lock control unit and suspension FlexRay to the powertrain control unit.
- ECO start/stop function enable issued by ME-SFI [ME] control unit
The ME-SFI [ME] control unit evaluates the coolant temperature (60 to 115°C) and engine speed for this purpose.
The ME-SFI [ME] control unit directly reads in the signals of the coolant temperature sensor (B11/4) and crankshaft Hall sensor and transmits the enable via the engine CAN (CAN C) to the powertrain control unit.
- Transmission oil temperature 10 to 120°C
The control unit for the fully integrated transmission control electric controller unit (Y3/8n4) transmits the transmission oil temperature via the drive CAN to the powertrain control unit.
- Drive range "D", "N" or "P" engaged
The control unit for the fully integrated transmission control electric controller unit transmits the engaged drive range via the drive CAN to the powertrain control unit.
- Accelerator not operated
The powertrain control unit directly reads in the signals of the accelerator pedal sensor (B37).
- ECO start/stop function enable issued by Electronic Stability Program control unit (N30/4)
To do this, the Electronic Stability Program control unit monitors the wheel speed and direction of rotation, brake application up to a standstill, and the vacuum in the brake booster.
The engine is not shut off after a maximum full-stop braking. The Electronic Stability Program control unit transmits the enable via the suspension FlexRay to the powertrain control unit.
Hood closed (except code U60 (Active hood (pedestrian protection)))
The front SAM control unit transmits the status of the hood via the interior CAN (CAN B), the electronic ignition lock control unit, and the suspension FlexRay to the powertrain control unit.
- Hood closed (with code U60 (Active hood (pedestrian protection)))
The Supplemental Restraint System control unit (N2/10) transmits the status of the hood via the user interface CAN, the electronic ignition lock control unit, and the suspension FlexRay to the powertrain control unit.
- ECO start/stop function enable issued by climate control unit (N22/1)
Once the vehicle interior temperature has been adjusted and the windshield is clear, the climate control unit transmits the enable via the interior CAN, electronic ignition lock control unit and suspension FlexRay to the powertrain control unit.
- 12 V on-board electrical system status OK
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.
- 48 V on-board electrical system status OK
The DC/DC converter control unit (N83/1) transmits the status of the 48 V on-board electrical system via the interior CAN, the electronic ignition lock control unit, and the suspension FlexRay to the powertrain control unit.
- Integrated starter alternator (A79) status
The starter-alternator control unit (N129) reads in the integrated starter alternator signals directly, and transmits the status (rotational speed and torque) via the hybrid CAN (CAN L) to the powertrain control unit.
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.
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.
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" additionally appears. If the ignition is not switched off, the ignition is automatically switched off after a minute.
Automatic engine start
The engine is started automatically if one of the following events occurs:
- The ECO start/stop function is deactivated via the ECO start/stop function button.
- The brake is released while the transmission is in drive range "D" or "N".
- No engine start occurs in drive range "P" when the brake is released.
- The accelerator pedal is operated.
- The drive range is shifted from "P" to another drive range.
No engine start occurs in the case of a change from drive range "D" or "N" to "P".
- The transmission mode is changed.
- Drive range "R" is engaged.
The powertrain control unit evaluates the input factors, and transmits the engine start request via the drive CAN to the ME-SFI [ME] control unit.
A maneuvering process is recognized for an engaged gear range "R" 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.
Upon activation of the Sport Plus mode, the ECO start/stop function is deactivated.
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 e.g. placed under strain by load-intensive consumers or a function or stop requirement is no longer met.
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:
- Exceeding of the engine stop period of a maximum of 3 minutes
- Detection of rolling backwards
- System or communication error of the following systems:
- On-board electrical system
- Brake system
- Accelerator pedal
- Transmission
- Motor
| Electrical function schematic for engine management, ECO start/stop function | Engine 256.9 in model 213, 238 up to model year 2021 | PE07.10-P-2724-97DBA | |
| Engine 256.9 in model 222 | PE07.10-P-2724-97SEM | ||
| Engine 256.9 in model 257 up to model year 2021 | PE07.10-P-2724-97XBB | ||
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