GF07.10-P-1041MM Engine Control, Start/Stop Function

GF07.10-P-1041MM Engine Control, Start/Stop Function
ENGINES 276.9 in MODEL 204.0 /2 /3 /9, 207.3 /4, 212.0 /2, 218
- with CODE (B03) ECO start/stop function

The partial function "Engine control, start/stop function" is viewed in terms of the engine control system.
Information for partial function "Energy management start/stop function" is documented in the function description "Energy management function".

Function requirements for the engine timing start stop function, general points
^ Engine running at operating temperature (coolant temperature: T greater than 60°C less than 115°C)
^ Speed of 15 km/h exceeded once during forward travel
^ Engine hood closed
^ Gear range "N"
^ System diagnosis completed

Engine control, start/stop function, general points
For a stationary vehicle, the 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 stopping the engine with the vehicle at a standstill. Conventional cutout and starting of the engine with the transmitter key (A8/1) or via the KEYLESS-GO start/stop button (S2/3) (for code (889) Keyless Go) continues to be possible.

The ME-SFI [ME] control unit (N3/10) permanently performs an SD and assesses the function requirements for the start stop function.
The front SAM control unit with fuse and relay module (N10/1) also checks the function of all involved components and transmits the status to the ME-SFI [ME] control unit via the chassis CAN (CAN E).

If the function requirements are fulfilled, the driver is notified of start/stop readiness by the "ECO" symbol in the multifunction display (A1p13) in the instrument cluster (A1).

For the start-stop function the ME-SFI [ME] control unit reads in the following sensors and signals:

- Coolant temperature sensor (B11/4) (model 204, 207, 212), coolant temperature sensor (B11/4) (model 218)
- Accelerator pedal sensor (B37), accelerator pedal actuation
- Crankshaft Hall sensor (B70), engine speed
- Instrument cluster, vehicle speed via chassis CAN
- Supplemental restraint system control unit (N2/10) (model 204, 207, 212), supplemental restraint system control unit (N2/10) (model 218), direct crash signal
- Supplemental restraint system control unit (model 204, 207, 212), supplemental restraint system control unit (model 218) via the chassis CAN
- Indirect crash signal
- Status of driver seat belt
- Signal engine hood closed (with code (U60) Pedestrian protection)
- Front SAM control unit with fuse and relay module:
- Air conditioning status
- Engine stop prohibition
- Engine start request
- Signal from the door contact on the front left
- ECO start/stop function button (N72/1s50) status
- Signal engine hood closed (with code (551) Anti-theft alarm system (ATA))
- Electrically stability program control unit (N30/4) (except code (233) DISTRONIC PLUS) or Premium electrically stability program control unit (N30/7) (with code (233) DISTRONIC PLUS), via the chassis CAN
- Brake actuation
- Wheel speed
- Engine start request
- Engine start request
- Engine stop enable
- Engine stop prohibition

- AIRMATIC control unit (N51/3) (with code (489) AIRMATIC (air suspension with continuous adjustable damping) via chassis CAN:
- Engine stop prohibition
- Engine start request
- Radar sensors control unit (N62/1) (model 207.3/4 up to 31.5.11 with code (233) DISTRONIC PLUS, model 212.0/2 up to 31.5.10 with code (233) DISTRONIC PLUS or code (234) Blind Spot Assist) or video and radar sensor system control unit (N62/2) (model 212.0/2 as of 01.06.10, model 204.0/2 and model 207.3/4 as of 01.06.11, model 204.3 with code (233) DISTRONIC PLUS, with code (237) Active Blind spot Assist, with code (238) Active Lane Keeping Assist), engine torque request (increase or reduction) via the chassis CAN
- Steering column module control unit (N80), steering wheel angle via the chassis CAN
- Steering column tube module control unit, steering wheel angular velocity via the chassis CAN
- Fuel system control unit (N118), fuel pressure via the drive train CAN (CAN C)
- Fully integrated transmission control controller unit (Y3/8), status of drive stage via drive CAN

The Electronic Stability Program control unit (N30/4) will be introduced into service as of 1.3.2011 (model 204.0/2) or as of 1.6.2011 (model 204.3) in 2 variants:
- Electronic Stability Program control unit, basic variant (except code (233) DISTRONIC PLUS)
- Electronic Stability Program control unit, Premium variant (except code (233) DISTRONIC PLUS)

From 1.6.2011 only the basic variant of the Electronic Stability Program control unit will be used in model 204.9.

Engine control, start/stop function, function sequence
The start/stop function consists of the following partial functions:

^ Function sequence for engine stop
^ Function sequence for engine start
^ Function sequence for forced engine start

Function sequence for engine stop

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

- Indicator lamp on the ECO start/stop function button lights up
- Vehicle speed = 0 km/h
- Coolant temperature greater than 60°C and less than 115°C
- Transmission oil temperature greater than 10°C and less than 120°C
- Engine oil temperature in the specified value range
- Engine rpm in specified value range
- Gear range "N"
- Accelerator not operated
- Service brake actuated up to standstill of the vehicle
- Adequate vacuum in the brake booster
- No control intervention function from AIRMATIC, brake assistance and distance regulation system
- Engine hood closed
- No crash signal
- Steering wheel angle a maximum of 210°
- Steering wheel angular velocity in the specified value range
- Outside temperature in range
- Condition of the on-board electrical system OK
- Driver door closed
- Driver seat belt applied
- Interior temperature regulated

After an automatic engine stop a maximum of three automatic engine stops are permitted without exceeding the speed 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.

Function sequence for engine start
The engine is started automatically for actuation of the accelerator pedal.
The ME-SFI [ME] control unit actuates the circuit 50 starter relay (N10/1kM) 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 FSCU receives the CAN signal "fuel specified pressure" from the ME-SFI [ME] control unit via the drive train CAN and appropriately actuates the fuel pump (M3) by means of a pulse width modulated signal (PWM signal).

Function sequence for a forced engine start
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 conditions occurs:

- Condition of the on-board electrical system not OK
- Coolant temperature greater than 115°C
- Exceeding of the engine stop period of a maximum of 3 minutes
- Change in the status of the A/C
- AIRMATIC, brake assist or distance regulation system in control intervention function mode
- A brake application cannot be safely completed once initiated
- The vacuum in the brake booster is not adequate
- Driver absence detected
- Change of the steering wheel angle by more than 8°
- Vehicle speed greater than 2 km/h
- Communication error of the start/stop function with one of the following systems: suspension and steering functions, energy management, brake and control systems

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