Eco Start/Stop Function Engine Management, Function - GF07.10-P-1042MNA
Engine 177.9 in model 205, 213, 253
The ECO start/stop function is seen from the point of view of the engine management.
Function requirements, general
- Terminal 15 ON
- Circuit 87 M (engine management) On
- Engine runs
- Outside temperature in range: -10 to 40°C
- Speed of 8 km/h exceeded once during forward travel
- Economy "E", Comfort "C" or Individual "I" transmission mode selected
- System diagnosis complete and fault-free
ECO start/stop function, general points
When a vehicle is stopped, the ECO start/stop function switches the engine off automatically and starts it again as soon as the driver wishes to drive off, if the energy management system thinks it is necessary, or if the windows fog up on the inside. 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 ECO start/stop function is activated by pressing the ECO start/stop function button (N725s3/). The right lower control panel (N72/5) directly reads in the status of the ECO start/stop function button and sends it via the LCP-LIN (LIN A3), Audio/COMAND control panel (A40/9) (model 213 except code 446 (touchpad only), model 205, 253) or touchpad (A105) (model 213 with code 446 (touchpad only)), telematics CAN (CAN A), head unit (A26/17), user interface CAN (CAN HMI), 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 (N3/10).
The ME-SFI [ME] control unit permanently performs an SD and assesses the system conditions for the ECO start/stop function.
All systems involved in the ECO start/stop function (e.g. energy management, air conditioning system) continuously check their status and transmit any engine start requirements via interior CAN (CAN B), electronic ignition lock control unit, suspension FlexRay, powertrain control unit and drive CAN to the ME-SFI [ME] control unit.
If the function requirements are fulfilled, the driver is notified of the ECO start/stop function readiness by the LED in the ECO start/stop function button and the "ECO" symbol in the instrument cluster (A1). The ME-SFI [ME] control unit sends the request to switch on the ECO start/stop function indicator lamp via the drive CAN, powertrain control unit, suspension FlexRay, electronic ignition lock control unit, user interface CAN, head unit and telematics CAN to the Audio/COMAND control panel or the touchpad. The Audio/COMAND control panel or the touchpad sends the request to switch on the ECO start/stop function indicator lamp via the LCP-LIN to the lower control panel, which actuates the LED in the ECO start/stop function button.
In addition, the ME-SFI [ME] control unit transmits the status of the ECO start/stop function via drive CAN, powertrain control unit, suspension FlexRay, electronic ignition lock control unit and user interface CAN to the instrument cluster.
The ECO start/stop function encompasses the following subfunctions:
- Automatic engine stop
- Automatic engine start
- Forced engine start (start dictated by the system)
Automatic engine stop
The engine is switched off by the ME-SFI [ME] control unit if all of the following function requirements are fulfilled:
- System diagnosis successfully completed, the ECO start/stop function button indicator lamp is lit
The ME-SFI [ME] control unit sends the request to actuate the indicator lamp of the ECO start/stop function button to the right lower control panel.
- Coolant temperature between 60 and 115°C
- Transmission oil temperature between 10 and 120°C
- Engine RPM in specified value range
- Gear range "D" or "N" engaged
- Accelerator not operated
- Vehicle speed 0 km/h
- 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
- No crash signal
- On-board electrical system in stable condition
- Driver door closed
- Driver seat belt applied
- Steering wheel angular velocity in the specified value range
- Interior temperature regulated
- No previous maximum full-stop braking To control the ECO start/stop function, the ME-SFI [ME] control unit reads in the signals from the following sensors and control units:
- Coolant temperature sensor (B11/4)
- Accelerator pedal sensor (B37) (model 205, 253)
On model 213 the powertrain control unit directly reads in the signals from the accelerator pedal sensor and sends them via the drive CAN to the ME-SFI [ME] control unit.
- Crankshaft Hall sensor (B70)
- Vehicle speed from instrument cluster
The instrument cluster transmits the vehicle speed via the user interface CAN, the electronic ignition lock control unit, the suspension FlexRay, the powertrain control unit and the drive CAN to the ME-SFI [ME] control unit.
- Crash signal, status of driver seat belt from the Supplemental Restraint System control unit (N2/10)
The supplemental restraint system control unit transmits the crash signal to the ME-SFI [ME] control unit via a direct line and redundantly via the suspension FlexRay, powertrain control unit, engine CAN and drive CAN. In addition, the supplemental restraint system control unit sends the status of the driver seat belt via the suspension FlexRay, powertrain control unit and engine CAN to the ME-SFI [ME] control unit.
- On-board electrical system information from the front SAM control unit (N10/6)
The front SAM control unit assesses the load on the on-board electrical system and sends this information via the interior CAN, electronic ignition lock control unit, suspension FlexRay, powertrain control unit and drive CAN to the ME-SFI [ME] control unit. If the load on the on-board electrical system is high, the front SAM control unit can request a forced engine start.
- Electronic Stability Program control unit (N30/4)
The Electronic Stability Program control unit transmits the following signals via the chassis FlexRay, the powertrain control unit and the drive train CAN to the ME-SFI [ME] control unit:
- Wheel speed
- Service brake, status
- Engine start request
- Engine stop prohibition
- Information on transmission control from the fully integrated transmission control unit (Y3/8n4)
The fully integrated transmission control unit sends information on the transmission oil temperature and the engaged drive range via the drive CAN to the ME-SFI [ME] control unit.
- Driver's door closed from left front door control unit (N69/1) The left front door control unit sends the status of the driver's door via the interior CAN, electronic ignition lock control unit, suspension FlexRay, powertrain control unit and drive CAN to the ME-SFI [ME] control unit.
- Steering motions from the steering column tube module control unit (N80) The steering column tube module control unit sends information on steering motions via the suspension FlexRay, powertrain control unit and drive CAN to the ME-SFI [ME] control unit.
- Engine start request from air conditioning system If window fogging is imminent or in case of rising interior temperatures, the Climate Control control unit (N22/1) sends the engine start request via the interior CAN, electronic ignition lock control unit, suspension FlexRay, powertrain control unit and drive CAN to the ME-SFI [ME] control unit.
- Request to increase or decrease engine torque from the radar sensors control unit (N62/1) (model 205, 253 with code 23P (Driving Assistance Package)) or from the Intelligent Drive control unit (N62/4) (model 213 with code 23P (Driving Assistance Package) or code P20 (Driving Assistance Plus Package))
The radar sensors control unit or the Intelligent Drive control unit sends the request to increase or decrease the engine torque via the suspension FlexRay to the Electronic Stability Program control unit. The Electronic Stability Program control unit interprets this request and accordingly transmits the engine torque increase or decrease request via the suspension FlexRay, powertrain control unit and drive CAN to the ME-SFI [ME] control unit.
- Fuel pressure from the fuel system control unit (N118)
The fuel system control unit transmits the fuel pressure via the drive train CAN to the ME-SFI [ME] 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 be restarted in this case.
Automatic engine start
The ME-SFI [ME] control unit automatically starts the engine when the accelerator pedal is pressed or the brake released.
The ME-SFI [ME] control unit actuates the circuit 50 starter relay (K40/8kH) 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 ME-SFI [ME] control unit also transmits the specified fuel pressure via the drive CAN to the fuel system control unit, which actuates the fuel pump (M3) accordingly.
Forced engine start (start dictated by the system)
The engine is automatically force-started (without the driver taking action) by the ME-SFI [ME] control unit if one of the following conditions is met:
- On-board network condition requires the engine to run.
- Coolant temperature above 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 absence recognition (driver seat belt is unfastened or driver's door is opened)
- Change of the steering wheel angle by more than 8°
- Vehicle speed above 2 km/h with forward travel and immediately if reverse travel is detected
- System or communication error of one of the following systems or components:
- Presence of driver
- Steering
- On-board electrical system
- Brake system
- Accelerator pedal Transmission
- Starter
- Motor
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.
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 205, 253 Engine 177.9 in model 213 |
PE07.10-P-2724-97FBD PE07.10-P-2724-97DBG |
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| Overview of system components for gasoline injection and ignition system with direct injection | Engine 177.9 in model 205, 253 Engine 177.9 in model 213 |
GF07.70-P-9998MNA GF07.70-P-9998MNE |