Starting, Function - GF07.10-S-1001TRJ

Engine 274 in model 447.6/7 

with code XM0 (Facelift) 

Starting function requirements, general points 

• Circuit 87M ON (Engine management ON)
• Engine OFF
• Start enable drive authorization system stage 4 (DAS 4)
• Engaged gear range "P" or "N" (with automatic transmission)

Starting, general points 

For starting, the ME-SFI [ME] control unit (N3/34) reads in signals from the following assembly parts:

• Intake camshaft Hall sensor (B6/29)
• Exhaust camshaft Hall sensor (B6/30)
• Coolant temperature sensor (B11/21)
• Crankshaft Hall sensor (B70/2)
• Circuit 87M relay (K40/10kN)
• Fully integrated transmission control (VGS) electric controller unit (N15/11) (Automatic transmission with code G42 (7G-TRONIC PLUS))
• Fully integrated transmission control (VGS) electric controller unit (N15/15) (Automatic transmission with code G43 (9G-TRONIC))
• Clutch pedal switch (S40/3) and clutch pedal switch (S40/6) (with manual transmission)
• Electronic ignition lock control unit (EIS) (N73)
• Oil level check switch (S43/5)

The ME-SFI [ME] control unit (N3/34) actuates the following assembly parts to start the engine:

• Starter (M1) via starter circuit 50 relay (K40/10kM)
• Ignition coils (T1)
• Fuel injectors (Y62)
• Fuel system control unit (FSCU) (N118) (with code G42 (7G-TRONIC PLUS)) and thus the fuel pump with fuel delivery module (M3/3)
• Fuel system control unit (FSCU) (N118/9) (with code G43 (9G-TRONIC)) and thus the fuel pump with fuel delivery module (M3/3)

The ME-SFI [ME} control unit (N3/34) coordinates for starting the injection and firing order from the signals of the crankshaft Hall sensor (B70/2), of intake camshaft Hall sensor (B6/29) and the exhaust camshaft Hall sensor (B6/30).

The starter control in the ME-SFI [ME] control unit (N3/34) takes on actuation and cutout of the starter (M1).

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 

By turning the transmitter key (A8/1) to the start position, the ME-SFI [ME] control unit (N3/34) receives the "circuit 50" signal from the electronic ignition lock control unit (EZS) (N73).

The ME-SFI [ME] control unit (N3/34) actuates the starter circuit 50 relay (K40/10kM) with a ground signal. The power contact of the starter circuit 50 relay (K40/10kM) closes and the solenoid switch of the starter (M1) is supplied with power from circuit 30 at circuit 50.

Function sequence for start end (with automatic transmission) 

Starter control is carried out automatically by the ME-SFI [ME] control unit (N3/34). This means that once the starting procedure is initiated, cutout of circuit 50 will have no further influence on the starting procedure. Where the engine cranking speed of 400 to 700 rpm or a starting time of approx. 5 to 40 s (depending on the coolant temperature) is reached, the ME-SFI [ME] control unit (N3/34) interrupts the negative activation to the starter circuit 50 relay (K40/10kM) and thus ends the starting procedure. The starting procedure can only be aborted by switching off the ignition.

If a start is repeated, a blocking period of approx. 1.5 to 3 s is waited for after ending the starting procedure. This occurs so that the rotating pinion of the starter (M1) is prevented from meshing with the toothing on the engine clutch plate (ring gear protection).

If the ME-SFI [ME] control unit (N3/34) detects engine running via the crankshaft Hall sensor (B70/2) and the signal "circuit 61 ON" as well as that the starting procedure has ended via the signal "circuit 50 OFF", the driver can regulate the injection quantity and thus the engine speed via the accelerator pedal module (B37/4).

	Function schematic for starting		PE07.10-S-2507-97TRM
	Overview of system components for gasoline injection and ignition system with direct injection		GF07.70-S-9998TRJ