Starting, Function - GF07.10-D-1001TSB

Engine 274 in model 907 

Block diagram 

Starting function requirements, general points 

• Circuit 87M (Engine management ON)
• Engine OFF
• Start enable drive authorization system stage 4 (DAS 4)
• Engaged drive range "P" or "N" (automatic transmission)
• Clutch travel sensor, full clutch operation (manual transmission with code MJ8 (ECO start/stop function))
• Clutch pedal switch (manual transmission without code MJ8 (ECO start/stop function))
• Clutch pedal switch UP (manual transmission without code MJ8 (ECO start/stop function))

Starting, general points 

The ME-SFI [ME] control unit (N3/36) reads in the following signals for starting:

• Exhaust camshaft Hall sensor, exhaust camshaft position for ignition circuit detection
• Coolant temperature sensor
• Crankshaft Hall sensor, engine speed
• Starter
• Ignition coils
• Fuel injectors
• Fuel system control unit via the drive CAN and thus the fuel pump with fill level sensor

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

Function sequence for start 

The starter control in the ME-SFI [ME] control unit takes on actuation and cutout of the starter. 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 actuating the ignition key in the start position or the start/stop button (S2/2), the ME-SFI [ME] control unit receives the "circuit 50" signal.

Function sequence for start end 

• Oil level check switch
• Electronic ignition lock control unit (EZS), "circuit 50" signal via the suspension FlexRay, powertrain control unit and engine CAN

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

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 the engine cranking speed has reached 400 to 700 RPM or a starting time of approx. 5 to 40 s (depending on the coolant temperature), the ME-SFI [ME] control unit interrupts the negative activation to the circuit 50 (F152kC) starter relay and thus ends the starting procedure.

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

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