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

Engine 176.9, 177.9 in model 217 

Engine 176.9, 177.9 in model 222 

Engine 177.9 in model 290 

up to model year 2021 

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

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

Function requirements ECO start/stop function, general points 

• Circuit 15 (ignition ON)
• Circuit 87 M (engine management ON)
• Engine runs
• Outside temperature in range: -10 to 40°C
• System diagnosis complete and fault-free
• Speed of 8 km/h exceeded once during forward travel
• Sport, Sport Plus, or Race drive program not selected

ECO start/stop function, general points 

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. The fuel consumption and thus the exhaust emissions are reduced by cutting out the engine with the vehicle at a standstill.

The conventional switching off and starting of the engine via the KEYLESS-GO start/stop button (S2/3) (for code 889 (KEYLESS-GO)) is still possible.

The ME-SFI control unit (N3/10) permanently performs a system diagnosis and assesses the system conditions for the ECO start/stop function.

All of the systems participating in the ECO start/stop function constantly check their status and send this to the powertrain control unit (N127) and via drive CAN (CAN C1) to the ME-SFI control unit. If the function requirements are fulfilled, the driver is notified of the ECO start/stop function readiness by the "ECO" symbol in the instrument cluster (A1).

Function sequence for ECO start/stop function 

The ECO start/stop function consists of the following partial functions:

• Function sequence for automatic engine stop 
• Function sequence for automatic engine start 
• Function sequence for forced engine start (a start dictated by the system) 

Function sequence for automatic engine stop 

The engine is switched off by the ME-SFI control unit if all of the following function requirements are fulfilled:

• Indicator lamp of ECO start/stop function button (N72s9) (with code 446 (Touchpad only)) or ECO start/stop function button (A40/9s9) (with code 448 (Touchpad)) lights up = system is fault-free and ECO start/stop function is activated.
• Vehicle speed = 0 km/h
• Coolant temperature between 60°C and 115°C
• Transmission oil temperature between 10°C and 120°C
• Engine rpm in specified value range
• Gear range "D" or "N"
• Accelerator not operated
• Service brake actuated up to standstill of the vehicle
• Adequate vacuum in the brake booster
• No control intervention functions from the brake and driver assistance systems
• Engine hood closed
• No crash signal
• Steering angle rate of change in specified value range
• Condition of the on-board electrical system OK
• Interior temperature regulated
• No previous maximum full-stop braking

The ME-SFI control unit reads in signals from the following sensors and control units to fulfill the function requirements:

• Coolant temperature sensor (B11/4), coolant temperature
• Accelerator pedal sensor (B37), accelerator pedal actuation
• Crankshaft Hall sensor (B70), engine speed
• Instrument cluster, vehicle speed via drive CAN, powertrain control unit, chassis FlexRay (Flex E), electronic ignition lock control unit (N73) and user interface CAN (CAN HMI)
• ECO start/stop function button (with code 446 (touchpad only)):

  Via drive CAN, powertrain control unit, suspension FlexRay, electronic ignition lock control unit, and user interface CAN, head unit (A26/17), telematics CAN (CAN A), touchpad (A105), LCP-LIN (LIN A3), lower control panel (N72)

• ECO start/stop function button (with code 448 (Touchpad)):

  Via drive CAN, powertrain control unit, suspension FlexRay, electronic ignition lock control unit, and user interface CAN, head unit, telematics CAN, Audio/COMAND control panel (A40/9)

• Supplemental restraint system control unit (N2/10), direct crash signal
• Supplemental Restraint System control unit via drive CAN, powertrain control unit, suspension FlexRay, electronic ignition lock control unit, and user interface CAN:
  • Indirect crash signal
  • Status of driver seat belt
  • Engine hood signal closed (for code U60 (Active engine hood (pedestrian protection)))
• Front SAM control unit (N10/6) via drive CAN, powertrain control unit, suspension FlexRay, electronic ignition lock control unit, and interior CAN (CAN B):
  • Engine stop prohibition
  • Engine start request
  • Left front door closed signal (N69/1)
  • Signal engine hood closed (with code (551) Anti-theft alarm system (ATA [EDW]))
• Control unit for climate control (N22/1) via drive CAN, powertrain control unit, suspension FlexRay, electronic ignition lock control unit, and interior CAN:
  • A/C status
  • Engine stop prohibition
  • Engine start request
• Electronic Stability Program control unit (N30/4) via drive CAN, powertrain control unit, suspension FlexRay:
  • Brake actuation
  • Wheel speed
  • Engine start request
  • Engine stop prohibition
  • Engine stop release
  • Torque request (increase or decrease)
• Mercedes-Benz Intelligent Drive control unit (N62/4) (with code 23P (Driving Assistance Package)), engine torque request (increasing or reducing) over drive CAN, powertrain control unit, suspension FlexRay
• Steering column tube module control unit (N80), steering wheel angle and steering wheel angular velocity via drive train CAN, powertrain control unit, suspension FlexRay
• FSCU (N118), fuel pressure via the drive CAN
• Fully integrated transmission control unit (Y3/8n4) (model 217, 222), drive range status via drive CAN
• Fully integrated transmission control electric controller unit control unit (Y3/8n4) (model 290), drive range status via the drive CAN

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 be restarted using the start-stop-button KEYLESS-GO.

Function sequence for automatic engine start 

The engine is automatically started upon actuating the accelerator pedal or releasing the service brake.

The ME-SFI control unit actuates the circuit 50 starter relay (K40/8 kH) with a ground signal. The power contact on the relay closes and the starter solenoid switch (M1) is supplied at "circuit 50" with a voltage from "circuit 30".

The fuel system control unit receives the CAN signal "Fuel specified pressure" from the ME-SFI control unit via the drive CAN and actuates the fuel pump (M3) with a pulse width modulated signal accordingly.

Function sequence for forced engine start (a start dictated by the system) 

The forced engine start subfunction is available as a protection function. Here the engine is force started autonomously (without any action taken by the driver) by the ME-SFI control unit if one of the following function requirements occurs:

• On-board network condition requires the engine to run.
• Coolant temperature >115°C
• Exceeding of the engine stop period of a maximum of 3 minutes
• A/C required engine running (e.B. windshield fogged up).
• Vacuum at brake booster not in specified range
• Brake assistance and distance control system in control intervention function
• Driver presence recognition (driver seat belt or driver door is opened)
• Change of the steering wheel angle by more than 8°
• Vehicle speed > 2 km/h for forward travel and immediately for recognition of rolling backwards
• System or communication error from one of the following systems: driver presence, steering, on-board electrical system, brake system, accelerator pedal, transmission, engine

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. The engine is also started if the driver door is opened, the driver seat belt buckle is opened or the ECO start/stop function is switched off via the ECO start/stop function button.

When the "Sport", "Sport Plus" or "Race" transmission mode is activated, the ECO start/stop function is deactivated.

	Electrical function schematic for engine management, ECO start/stop function	Engine 177.9 in model 290 up to model year 2021	PE07.10-P-2724-97XBA
		Engine 176.9, 177.9 in model 217Engine 176.9, 177.9 in model 222	PE07.10-P-2724-97SEL
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