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Starting, Function - GF07.10-P-1001MRG

Engine 264.9 in model 213, 238, 257 

up to model year 2021 

Function requirements, general 

IMPORTANT The fully integrated transmission control electric controller unit control unit (Y3/8n4) transmits information on the engaged drive range via the drive CAN (CAN C1) to the ME-SFI [ME] control unit (N3/10). The Electronic Stability Program control unit (N30/4) transmits the information on the service brake status via the suspension FlexRay (Flex E), powertrain control unit and drive CAN to the ME-SFI [ME] control unit.

Start 

The ME-SFI control unit reads in the following signals for starting:

The powertrain control unit reads in the signals from the starter-alternator via the hybrid CAN (CAN L) and transmits the status (rotational speed and torque) via the drive CAN to the ME-SFI [ME] control unit.

The ME-SFI [ME] control unit actuates the following assembly parts to start the engine:

The ME-SFI [ME] control unit transmits the request to actuate the fuel pump both directly and 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 directly actuates the fuel pump.

The ME-SFI [ME] control unit transmits the request to start the engine via the engine CAN (CAN C) to the powertrain control unit. The powertrain control unit evaluates all relevant variables and transmits the request to start the engine via the hybrid CAN to the starter-alternator.

The ME-SFI [ME] control unit coordinates the injection and firing order during starting based on the signals from the crankshaft Hall sensor and the intake camshaft and exhaust camshaft Hall sensors.

Start begin 

By actuating the KEYLESS-GO start/stop button, the ME-SFI [ME] control unit receives the "circuit 50 signal" from the electronic ignition lock control unit via the suspension FlexRay, powertrain control unit and drive CAN.

Vehicles except code B01 (48V technology) 

The ME-SFI [ME] control unit actuates the circuit 50 starter relay on both sides with a ground signal. The power contact on the starter relay closes and the starter solenoid switch is supplied at "circuit 50" with voltage from "circuit 30".

Vehicles with code B01 (48V technology) 

The ME-SFI [ME] control unit transmits the request to start the engine via the engine CAN to the powertrain control unit. The powertrain control unit evaluates all relevant variables and transmits the request to start the engine via the hybrid CAN to the starter-alternator.

When the KEYLESS-GO start/stop button is operated, the ME-SFI [ME] control unit requests the starting procedure from the powertrain control unit.

When the starting procedure is initiated, the shutting off of "circuit 50" will have no further influence on the starting procedure. The start process can only be canceled if circuit 15 is switched off.

IMPORTANT Engine 264.9 in model 213, 238, 257

up to model year 2021

except code B01 (48V technology)

The voltage dip limiter (R62) is installed at the positive pole of the on-board electrical system battery (G1). It is connected to the circuit 50 starter relay via circuit 50. When the engine is started, the voltage dip limiter switches in the integrated series resistor. This reduces the power consumption of the starter when the engine is cranked. The voltage drop, which is perceptible to the vehicle occupants when the engine is started, is reduced. If the on-board electrical system voltage drops too much due to the high power consumption of the starter, the voltage dip limiter switches the series resistor off again.

Ending start 

Starter control is carried out automatically by the ME-SFI [ME] control unit (touch start). This means that once a starting procedure is initiated, deactivating "circuit 50" no longer has an influence on the starting procedure.

Vehicles except code B01 (48V technology) 

When engine cranking speed has reached 400 to 700 RPM, or after a starting time of 5 to 40 s (dependent on coolant temperature), the ME-SFI [ME] control unit interrupts the negative activation of the circuit 50 starter relay and thus terminates the starting procedure.

Vehicles with code B01 (48V technology) 

The ME-SFI [ME] control unit transmits the engine speed via the engine CAN to the powertrain control unit. When the engine cranking speed of 400 to 700 RPM is reached or the starting time is between approx. 5 and 40 s (depending on the coolant temperature), the powertrain control unit cancels the starting procedure. It then transmits the signal "Engine running" via the suspension FlexRay, electronic ignition lock control unit and interior CAN to the DC/DC converter control unit.

The start process can be broken off through renewed actuation of the KEYLESS-GO start-stop button.

  Electrical function schematic for starting Engine 264.9 in model 213, 238 up to model year 2021 PE07.10-P-2701-97DBB
    Engine 264.9 in model 257 up to model year 2021 PE07.10-P-2701-97XBC
  Overview of system components for gasoline injection and ignition system with direct injection   GF07.70-P-9998MRG
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