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

Engine 256.9 in model 213, 238, 257, 290 

up to model year 2021 

Engine 256.9 in model 222 

Starting function requirements, general points 

• Drive range "P" or "N" engaged and foot brake actuated

The control unit for the fully integrated transmission control electric controller unit (Y3/8n4) transmits information about 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 information about the status of the service brake via the chassis FlexRay (Flex E), the powertrain control unit (N127) and the drive train CAN to the ME-SFI [ME] control unit.

Start 

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

• Intake camshaft position for ignition circuit detection

  Intake camshaft Hall sensor (B6/15)

• Exhaust camshaft position for ignition circuit detection

  Exhaust camshaft Hall sensor (B6/16)

• Coolant temperature

  Coolant temperature sensor (B11/4)

• Engine speed

  Crankshaft Hall sensor (B70)

• Circuit 50 status

  The electronic ignition lock control unit (N73) reads in the signals of the KEYLESS-GO start/stop button (S2/3) directly, and transmits the status of circuit 50 via the suspension FlexRay, the powertrain control unit, and the drive CAN to the ME-SFI [ME] control unit.

• Oil level

  Engine oil fill level sensor (B40/6)

• Drive range, transmission oil temperature

  The control unit for the fully integrated transmission control electric controller unit transmits the information via the drive CAN to the ME-SFI [ME] control unit.

• 48 V on-board electrical system state and voltage, 48 V on-board electrical system battery (G1/3) charge level

  The DC/DC converter control unit (N83/1) transmits the information via the interior CAN (CAN B), the electronic ignition lock control unit, the suspension FlexRay, the powertrain control unit, and the drive CAN to the ME-SFI [ME] control unit.

• Integrated starter alternator (A79) status

The starter-alternator control unit (N129) reads in the starter-alternator signals directly, and transmits the status (rotational speed and torque) via the hybrid CAN (CAN L), the powertrain control unit, and 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:

• Ignition system
  • Cylinder 1 ignition coil (T1/1)
  • Cylinder 2 ignition coil (T1/2)
  • Cylinder 3 ignition coil (T1/3)
  • Cylinder 4 ignition coil (T1/4)
  • Cylinder 5 ignition coil (T1/5)
  • Cylinder 6 ignition coil (T1/6)
• Fuel injection system
  • Cylinder 1 fuel injector (Y76/1)
  • Cylinder 2 fuel injector (Y76/2)
  • Cylinder 3 fuel injector (Y76/3)
  • Cylinder 4 fuel injector (Y76/4)
  • Cylinder 5 fuel injector (Y76/5)
  • Cylinder 6 fuel injector (Y76/6)
• Fuel pump (M3)

  The ME-SFI [ME] control unit transmits the request to actuate the fuel pump directly and via the drive CAN to the fuel system control unit (N118). The ME-SFI [ME] control unit additionally 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.

• Integrated starter generator

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 control unit. The starter-alternator control unit actuates the integrated starter alternator directly.

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.

Ending start 

Starting 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.

The ME-SFI [ME] control unit transmits the engine speed via the engine CAN to the powertrain control unit. On reaching the engine cranking speed of 400 to 700 RPM or a starting time of approx. 5 to 40 s (depending on the coolant temperature), the powertrain control unit stops the starting procedure. It then transmits the "Engine running" signal via the suspension FlexRay, the electronic ignition lock control unit, and the 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 256.9 in model 213, 238 up to model year 2021	PE07.10-P-2701-97DBA
		Engine 256.9 in model 222	PE07.10-P-2701-97SEM
		Engine 256.9 in Model 257	PE07.10-P-2701-97XBB
	Overview of system components for gasoline injection and ignition system with direct injection		GF07.70-P-9998MRT