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Engine Timing Start-Stop Function - GF07.10-P-1041KJ

ENGINE 281.910 in MODEL 453.0/3/4 

with CODE B03 (ECO start/stop function) 

IMPORTANT The "Engine management, start/stop function" subfunction is examined from the point of view of the engine management.

Function requirements for engine management, start/stop function, general points 

Engine management start-stop function, general 

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.

Switching the engine on and off in a conventional manner using the key (A81) over the ignition lock (S2) is still possible.

The driver-side SAM control unit (N10/11) continuously 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 continuously check their status and transmit this to the driver-side SAM control unit.

For fulfilled function requirements the driver is shown the state of the operating readiness of the ECO start/stop function as accessible by the ECO start/stop function indicator lamp (A1e63) or not accessible by the ECO start/stop function indicator lamp (A1e62) in the IC (A1) (for code K35 (IC with a monochrome display)) or (for code K36 (IC with a color 8.9 cm (3.5") display)).

IMPORTANT The start-stop function occurs over the driver-side SAM control unit (Master of the System) and the ME-SFI [ME] control unit (N3/10) which actuates the automatic engine stop. Automatic starting on the driver's request and therefore automatic actuation of the starter (M1), after an automatic engine stop, takes place by the center SAM control unit (N10/10) via the starter relay (F2k5).

Engine management Start-Stop function, function sequence 

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

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:

The ME-SFI [ME] control unit reads in the following sensor signals in order to check whether all function requirements are fulfilled:

AWF controller unit with radar sensor (A89) (for code 252 (AWF)) via front end CAN (CAN G), AWF Gateway (N93/2) (for code 252 (AWF)) and interior CAN:

Supplemental Restraint System control unit (N2/10) via the interior CAN:

Center SAM control unit and interior CAN:

Driver-side SAM control unit via interior CAN:

Climate control control unit (N22/1) (for code I01 (AAC)) via the interior CAN:

Electronic Stability Program control unit (N30/4) via the interior CAN:

Steering wheel angle sensor (N49) via chassis CAN (CAN E), Electronic Stability Program control unit and interior CAN:

DKG control unit (N15/13) (for code 429 (twinamic)) via drive train CAN (CAN C)

Function sequence for automatic engine start 

For actuation of the acceleration or clutch pedal, the engine is started automatically for a manual transmission (for code 410 (5-gear manual transmission)). For a DKG (code 429 (twinamic)), the engine is started automatically upon release of the brake or actuation of the accelerator pedal. The center SAM control unit actuates the starter (M1) over the starter relay (F2k5). The power contact on the starter relay closes and the starter solenoid switch is supplied at "circuit 50" with voltage from "circuit 30". The automatic engine start is recognized by the ME-SFI [ME] control unit over the starting speed which the ignition coils/fuel pump relay actuation (F11k3) switches and therefore the fuel pump with fill level sensor and temperature sensor (M3/3).

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

IMPORTANT The partial function "engine forced start" is seen from the point of view of the engine management. Partial functions of other systems such as engine forced start on the part of the energy management (ENM), the electric power steering (ES), the AAC (KLA) and the brake system are not described in detail in this description.

The forced engine start subfunction is available as a protection function. Here the engine is force started autonomously (with any action on the part of the driver) by the system. The ME-SFI [ME] control unit can also initiate the forced engine start based on grounds from the engine management or the DKG (for code 429 (twinamic)). If the system registers the absenteeism of the driver or an opened engine hood, no system-based forced engine start will be carried out on safety grounds. A forced engine start is initiated when one of the following function requirements occur:

IMPORTANT

IMPORTANT A maneuvering process is recognized for an engaged reverse gear 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 forward gear and for exceeding a vehicle speed of 10 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.

  Electrical function schematic for engine timing, start/stop   PE07.10-P-2722-97BBA 
  Overview of system components motor electronics (ME-SFI) fuel injection and ignition system   GF07.61-P-9997KJ 
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