ECO Start/Stop Function Engine Management, Function - GF07.10-P-1042MNF
Engine 176.9 in model 463
as of model year 2016 up to model year 2019
with code MJ7 (ECO start/stop function)
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 87M (Engine management ON)
- Outside temperature in a range of: -10 to 40 °C
- System diagnosis complete and fault-free
- Speed of 8 km/h exceeded once during forward travel
- Off-road ratio in transfer case not switched in
The circuit relay 87M(F58kN) is switched on for circuit 15 ON. The instrument cluster (A1) transmits the vehicle speed via interior CAN (CAN B), electronic ignition lock control unit (N73), suspension CAN 1 (CAN E1), powertrain control unit (N127) and drive CAN (CAN C) to the ME-SFI [ME] control unit (N3/10).
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 ME-SFI [ME] control unit permanently performs an SD 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 and via drive CAN to the ME-SFI [ME] control unit.
If the function requirements are fulfilled, the driver is notified of the operational readiness of the ECO start/stop function by the appropriate symbol in the instrument cluster. The ME-SFI [ME] control unit transmits the status of the ECO start/stop function via drive CAN, powertrain control unit, suspension CAN 1, electronic ignition lock control unit and interior CAN to the instrument cluster.
Switching the engine on and off in a conventional manner using the transmitter key (A81) is still possible.
Function sequence for ECO start/stop function
The ECO start/stop function encompasses the following subfunctions:
- Function sequence for automatic engine stop
- Function sequence for automatic engine start
- Function sequence for forced engine start (a start dictated by the system)
Additional function requirements for automatic engine stop
- Engine runs
Function sequence for automatic engine stop
The engine is switched off by the ME-SFI [ME] control unit if all of the following function requirements are fulfilled:
- Indicator lamp for the ECO start/stop function button (N72/1s50) lights up (system is fault-free and ECO start/stop function is activated)
- Vehicle speed = 0 km/h
- Coolant temperature > 60°C and < 115°C
- Transmission oil temperature > 10°C and < 120°C
- Engine speed 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 wheel angular velocity in the specified value range
- Condition of the on-board electrical system OK
- Driver door closed
- Driver seat belt applied
- Interior temperature regulated
- No previous maximum full-stop braking
For the ECO start/stop function, the ME-SFI [ME] control unit reads in signals from the following sensors:
- Coolant temperature sensor (B11/4), coolant temperature
- Accelerator pedal sensor (B37), accelerator pedal actuation
- Crankshaft Hall sensor (B70), engine speed
- Supplemental restraint system control unit (N2/10), crash signal
The supplemental restraint system control unit sends the following signals via the suspension CAN 1, powertrain control unit and drive CAN (CAN C) to the ME-SFI [ME] control unit:
- Crash signal
- Driver seat belt buckle, status
The SAM control unit (N10) sends the following signals via the interior CAN, electronic ignition lock control unit, suspension CAN 1, powertrain control unit and drive CAN to the ME-SFI [ME] control unit:
- Engine stop prohibition, request
- Engine start, request
- Hood contact switch, status (with code FZ5 (Anti-Theft Alarm System (ATA)) or code FZ8 (Anti-Theft Protection Package))
- ECO start/stop function button, status (from SAM control unit via battery sensor LIN (LIN B15) read in)
The climate control, control and operating unit (N22/7) sends the following signals via the interior CAN, electronic ignition lock control unit, suspension CAN 1, powertrain control unit and drive CAN to the ME-SFI [ME] control unit:
- Engine stop prohibition, request
- Engine start, request
- Air conditioning, status
The Electronic Stability Program control unit (N304) transmits the following signals via suspension CAN 1, the powertrain control unit and drive CAN to the ME-SFI [ME] control unit:
- Engine stop prohibition, request
- Engine start, request
- Engine stop release, status
- Wheel speed
- Service brake, status
- Vacuum in brake booster, status
The left front door control unit (N691) sends the following signals via the interior CAN, electronic ignition lock control unit, suspension CAN 1, powertrain control unit and drive CAN to the ME-SFI [ME] control unit:
- Engine stop prohibition, request
- Driver door, status
The FSCU (N118) transmits the following signals via drive CAN to the ME-SFI [ME] control unit:
- Fuel pressure, signal
- Fuel level, signal
The steering column tube module control unit (N80) reads in the steering wheel angle sensor (N49) signal directly and transmits the following signals via suspension CAN 1, powertrain control unit and drive CAN to the ME-SFI [ME] control unit:
- Steering wheel angle
- Steering wheel angular velocity
The fully integrated transmission control unit (Y3/8n4) transmits the engaged gear range via drive CAN to the ME-SFI [ME] control unit. The instrument cluster sends the vehicle speed via the interior CAN, electronic ignition lock control unit, suspension CAN 1, powertrain control unit and drive 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 in the engine stop. Upon opening of the engine hood in automatic engine stop, the ECO start/stop function is switched off and all indicator lamps in the instrument cluster light up.
The engine must be newly started with the transmitter key.
Function sequence for automatic engine start
The engine is started automatically, if one of the following conditions applied:
- Switch off of function via ECO start/stop function button
- Operation of accelerator pedal
- Selection of gear range "R"
- Unfastening of driver's seat belt
- Driver door opened
- Releasing of the service brake
- Charge level of the on-board electrical system battery too low
- Activation of off-road ratio in transfer case
The ME-SFI [ME] control unit actuates the circuit 50 starter relay (F58kM) with a ground signal. The power contact on the relay closes and the starter solenoid switch (M1) is supplied at circuit 50 with voltage from circuit 30.
The ME-SFI [ME] control unit transmits the request fuel specified pressure via drive CAN to the FSCU. The fuel system control unit actuates the fuel pump (M3) appropriately by means of a PWM signal.
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 [ME] 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
- The temperature in the vehicle interior goes outside the selected range.
- Moisture build up noticed on the windshield (A/C switched on)
- Vacuum on the brake booster not in the nominal range (residual pressure in the brake booster does not fall below -200 mbar)
- 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
- Recognition of reverse rollers
- On-board network condition requires the engine to run.
- System or communication error of one of the following systems or assembly parts: driver presence, steering, on-board electrical system, brake system, accelerator pedal, transmission, starter, 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.
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