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

Engine 274 in model 447, 448

except code XM0 (Facelift)

Starting function requirements, general points

Circuit 87M ON (Engine management ON)
Engine OFF
Drive authorization system 4 (DAS 4) start enable
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) over direct line
Exhaust camshaft Hall sensor (B6/30) over direct line
Coolant temperature sensor (B11/21) over direct line
Crankshaft Hall sensor (B70/2) over direct line
Clamping device relay 87M (K40/10kN) over direct line
Fully integrated transmission control electric controller unit (VGS) (N15/11), via the drive train CAN (CAN C) (for an automatic transmission)
Electronic ignition lock control unit (EZS) (N73) via the chassis CAN (CAN E)
Clutch pedal switch (S40/3) and clutch pedal switch (S40/6) over direct line (with manual transmission)
Oil level check switch (S43/5) over direct line

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

Starter (M1) over clamping device 50 starter relay (K40/10kM) and direct line
Ignition coils (T1) over direct line
Fuel injectors (Y62) over direct line
FSCU (FSCU) (N118) and therefore the fuel pump with fill level sensor (M3/6) over direct line and via drive train CAN (CAN C)

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

Through turning the transmitter key (A8/1) into start position the ME-SFI [ME] control unit (N3/34) receives the signal "circuit 50' via chassis CAN (CAN E) from electronic ignition lock control unit (EZS) (N73).

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

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 start process is initiated, switching off "circuit 50" will have no further influence on the start procedure. When reaching an engine cranking speed of 400 up to 700 rpm and a starting time of approx. 5 to 40 seconds (dependent on the coolant temperature), the ME-SFI [ME] control unit (N3/34) the negative activation to terminal 50 starter relay (K40/10kM) and therefore ends the starting procedure. The starting procedure can only be aborted by switching off the ignition.

The starting procedure is inhibited for approximately 1.5 to 3 s before it can be repeated. 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) recognizes from the crankshaft Hall sensor (B70/2) and from the signal "terminal 61 ON" engine running as well as from the signal "terminal 50 OFF", that the start process is ended, so the driver can control the injection quantity and thus the engine rpm over the accelerator pedal module (B37/4).

Electrical function schematic for starting	Engine 274 in model 448 except code XM0 (Facelift)	PE07.10-S-2701-97VDC
	Engine 274 in model 447 except code XM0 (Facelift)	PE07.10-S-2701-97TRC
Overview of system components for gasoline injection and ignition system with direct injection		GF07.70-S-9998TRC