Ignition On, Function - GF07.10-P-1000MMK

Engine 276.8 in model 222.163/173

Engine 276.9 in model 222

Function requirements for ignition ON, general points

Terminal 30

Ignition ON, general points

For ignition ON, the engine management in the ME-SFI [ME] control unit (N3/10) is switched on and the combustion engine prepared for starting.

Function sequence for ignition ON

Upon switching on the ignition the engine compartment terminal 15 relay (K40/8kG) is switched on by the electronic ignition lock control unit (N73) via the interior CAN (CAN B).

The "Circuit 15 ON" signal is sent redundantly over the suspension FlexRay (Flex E) to the powertrain control unit (N127) and over the drive train CAN (CAN C1) to the ME-SFI [ME] control unit. The engine compartment circuit 15 relay forwards the on-board electrical system voltage from "circuit 30" to "circuit 15".

If a voltage is applied to the ME-SFI [ME] control unit at "circuit 15", the engine circuit relay 87M (K40/8kN) is actuated by means of a ground signal. This causes the relay to close its power contact and the voltage is forwarded from "circuit 30" (dependent on the respective fuses) as "circuit 87 M4" to the ME-SFI [ME] control unit and as "circuit 87 M1/2/3" to the respective sensors and actuators of the engine management.

If a voltage is present at "circuit 87M", the engine management is switched on and an output stage driver in the ME-SFI [ME] control unit takes over actuation of the engine circuit relay 87M.

The "circuit 31" ground connection is made by the on-board electrical system battery (G1) over the battery ground point (W10) and over a number of ground lines to the ME-SFI [ME]/CDI control unit (W25) ground point.

When the engine management is switched on, the ME-SFI [ME] control unit carries out the following functions:

The signal "terminal 15 ON" is led via the powertrain control unit and the hybrid CAN (CAN L) to the power electronics control unit (N129/1) and the battery management system control unit (N82/2).
The request "close contactor" is transmitted to the battery management system control unit.
To prevent cylinder flooding, the fuel pump (M3) is actuated directly over the fuel system control unit (N118) and also by the FSCU via the drive train CAN (only the first time the ignition is switched ON after the vehicle is unlocked).
In the instrument cluster (A1) the engine diagnosis symbol is actuated for a symbol check over the drive train CAN, powertrain control unit, suspension FlexRay, electronic ignition lock control unit and the user interface CAN (CAN HMI).
The throttle valve actuator (M16/6) checks its return spring (by the position of the throttle valve) and adapts the position of the actuator, if necessary.

The fault memory in the ME-SFI [ME] control unit can be read out and deleted via the diagnostic connector (X11/4). The diagnostic connector is networked to the electronic ignition lock control unit via the diagnostic CAN (CAN D) to the powertrain control unit via the chassis FlexRay and to the ME-SFI [ME] control unit via the drive train CAN.

Correction programming or diagnosis can be carried out with the XENTRY Diagnostics over the diagnostic connector.

Different characteristics maps for the engine management can be stored and activated with the correction programming in the ME-SFI [ME] control unit, such as:

Ignition map for adaptation to various fuel grades (RON correction (R esearch-O ctane N umber))
Mixture maps for enriching the fuel/air mixture in different operating states
Basic setting for idle speed
Idle speed for engaged gear range
Fault setting conditions for smooth running detection
Temperature correction for switching fan motor (M4/7) on and off

Electrical function schematic, ignition ON		PE07.10-P-2700-97SEC
Overview of system components for gasoline injection and ignition system with direct injection	Engine 276.9 in model 222	GF07.70-P-9998MMK
	Engine 276.8 in model 222.163	GF07.70-P-9998MMT