Ignition, Function - GF07.10-P-1023MRT

Engine 256.9 in model 213, 238, 257, 290 

up to model year 2021 

Engine 256.9 in model 222 

Ignition ON 

When circuit (ignition on) is switched on, the ME-SFI [ME] control unit (N3/10) starts the engine management system and prepares the engine for starting.

The electronic ignition lock control unit (N73) sends the status of circuit 15 via interior CAN (CAN B) to the front SAM control unit (N10/6). The front SAM control unit actuates the engine compartment circuit 15 relay (K40/8kG). The engine compartment circuit 15 relay switches the battery voltage (circuit 30) to circuit 15.

In addition, the electronic ignition lock control unit transmits the circuit 15 status via the suspension FlexRay (Flex E), powertrain control unit (N127) and drive CAN (CAN C1) to the ME-SFI [ME] control unit. The ME-SFI [ME] control unit then actuates the circuit 87M relay (K40/8kN). The circuit 87M relay switches the battery voltage (circuit 30) to circuit 87M. When circuit 87M is switched through to the ME-SFI [ME] control unit, it starts the engine management. A power amplifier driver in the ME-SFI [ME] control unit then takes over further actuation of the circuit 87M relay.

When it starts the engine management, the ME-SFI [ME] control unit carries out the following functions:

• Fuel supply

  The ME-SFI [ME] control unit transmits the "Fuel pump (M3) ON" request via a direct line and redundantly via the drive CAN to the fuel system control unit (N118). The ME-SFI [ME] control unit also transmits the specified fuel pressure via the drive CAN to the fuel system control unit. The fuel system control unit then accordingly actuates the fuel pump.

• Function test

  The ME-SFI [ME] control unit checks the function of the throttle valve actuator (M16/6) and performs an actuator adaptation if necessary.

Ignition OFF 

When the circuit 15 ON status changes to circuit 15 OFF, first the engine and then the engine management is deactivated in the ME-SFI [ME] control unit.

The electronic ignition lock control unit sends the status of circuit 15 to the front SAM control unit over the interior CAN. The front SAM control unit then ends the actuation of the engine compartment circuit 15 relay. The engine compartment circuit 15 relay opens and interrupts the power supply via circuit 15. If the power supply via circuit 15 has been deactivated, the ME-SFI [ME] control unit no longer actuates the circuit 87 relay. The circuit 87 relay opens and the engine management is deactivated.

The electronic ignition lock control unit also transmits the circuit 15 status via the suspension FlexRay, powertrain control unit and drive CAN to the ME-SFI [ME] control unit. The ME-SFI [ME] control unit then transmits the "Fuel pump OFF" request via a direct line and redundantly via the drive CAN to the fuel system control unit. The fuel system control unit then switches off the fuel pump.

The ME-SFI [ME] control unit also ends the actuation of the ignition and fuel injection systems and starts the computer run-on.