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

Engine 178.9 In Model 190 

Starting function requirements, general points 

• Circuit 87M (engine management ON)
• Engine OFF
• Drive authorization system 4 (DAS 4) start enable
• Engaged gear range "P" or "N"

Starting, general points 

The ME-SFI [ME control unit (N3/10) reads in signals from the following sensors for starting:

• Left and right intake camshaft Hall sensors (B6/4, B6/5), intake camshaft positions for ignition circuit detection
• Left and right exhaust camshaft Hall sensors (B6/6, B6/7), exhaust camshaft positions for ignition circuit detection
• Coolant temperature sensor (B11/4), coolant temperature
• Crankshaft Hall sensor (B70), engine RPM
• Electronic ignition lock control unit (N73), "Circuit 50 signal" via chassis CAN 1 (CAN E1), powertrain control unit (N127), and drive train CAN (CAN C1)

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

• Starter (M1)
• Ignition coils (T1)
• Fuel injectors (Y76)
• The fuel system control unit (N118) and thereby the fuel pump (M3) directly and over the drive train CAN

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 camshaft Hall sensors.

The starter control in the ME-SFI [ME] control unit takes on actuation and cutout of the starter.

Function sequence for start 

The starter control is subdivided into the following points:

• Function sequence for start begin 
• Function sequence for start end 

Function sequence for start begin 

When the ignition key (transmitter key (A8/1)) is moved to the start position, the ME-SFI [ME] control unit receives the "Circuit 50 signal" from the powertrain control unit via the powertrain CAN and from the electronic ignition lock control unit via the chassis CAN E1.

The ME-SFI [ME] control unit actuates the circuit 50 starter relay (N10/1kM) with a ground signal on both sides. The power contact on the starter relay closes and the starter solenoid switch is supplied at "circuit 50" with voltage from "circuit 30".

Function sequence for start end 

Starter control is carried out automatically by the ME-SFI [ME] control unit (touch start). This means that once the start process is initiated, switching off "circuit 50" will have no further influence on the start procedure.

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.

The starting procedure can only be aborted by switching off the ignition.

	Electrical function schematic for starting		PE07.10-P-2701-97HBA
	Overview of system components for gasoline injection and ignition system with direct injection		GF07.70-P-9998MNB