Starting, Function - GF07.10-P-1001MNA
Engine 177.9 in model 205, 253
Engine 177.9 in model 213
up to model year 2021
Function requirements, general
- Circuit 87M (Engine management) ON
- Gear range "P" or "N" engaged and foot brake actuated
The electronic ignition lock control unit (N73) transmits the status of circuit 15 via the chassis FlexRay (Flex E), the powertrain control unit (N127) and the drive train CAN (CAN C1) to the ME-SFI [ME] control unit (N3/10). The ME-SFI [ME] control unit then actuates the circuit 87M relay (K40/8kN). The circuit 87M relay switches the battery voltage (circuit 30) to circuit 87M. When circuit 87M is switched through to the ME-SFI [ME] control unit, it starts the engine management.
The fully integrated transmission control unit (Y3/8n4) sends information on the gear range engaged via the drive train CAN to the ME-SFI [ME] control unit.
The Electronic Stability Program control unit (N30/4) sends the status of the service brake via the chassis FlexRay, powertrain control unit and drive train CAN to the ME-SFI [ME] control unit.
Start
The ME-SFI [ME] control unit reads in signals from the following components for starting the engine:
- Left intake camshaft Hall sensor (B6/4) (ignition circuit detection)
- Right intake camshaft Hall sensor (B6/5) (ignition circuit detection)
- Left exhaust camshaft Hall sensor (B6/6) (ignition circuit detection)
- Right exhaust camshaft Hall sensor (B6/7) (ignition circuit detection)
- Coolant temperature sensor (B11/4)
- Crankshaft Hall sensor (B70)
The electronic ignition lock control unit transmits the status of circuit 50 via the chassis FlexRay, the powertrain control unit and the drive train CAN to the ME-SFI [ME] control unit.
The ME-SFI [ME] control unit evaluates all incoming information and actuates the following components:
- Starter (M1) over circuit 50 relay for starter (K40/8kH)
- Ignition system
- Cylinder 1+2 ignition coil (T4)
- Cylinder 1 ignition coil (T4t1)
- Cylinder 2 ignition coil (T4t2)
- Ignition coil, cylinders 3+4 (T4/1)
- Cylinder 3 ignition coil (T4/1t3)
- Cylinder 4 ignition coil (T4/1t4)
- Ignition coil, cylinders 5+6 (T4/2)
- Cylinder 5 ignition coil (T4/2t5)
- Cylinder 6 ignition coil (T4/2t6)
- Ignition coil, cylinders 7+8 (T4/3)
- Cylinder 7 ignition coil (T4/3t7)
- Cylinder 8 ignition coil (T4/3t8)
- Cylinder 1+2 ignition coil (T4)
- 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)
- Cylinder 7 fuel injector (Y76/7)
- Cylinder 8 fuel injector (Y76/8)
The ME-SFI [ME] control unit transmits the switch on fuel pump (M3) request via a direct line and redundantly via the drive train CAN to the fuel system control unit (N118). The ME-SFI [ME] control unit also transmits the specified fuel pressure via the drive train CAN to the fuel system control unit. The fuel system control unit then correspondingly actuates the fuel pump.
Start begin
The ME-SFI [ME] control unit actuates the circuit 50 starter relay on both sides with a ground signal. The relay power contact closes and power is supplied to the starter solenoid switch. The engine is started. The ME-SFI [ME] control unit coordinates the injection and firing order. When the starting procedure is initiated, the shutting off of "circuit 50" will have no further influence on the starting procedure. The start process can only be canceled if circuit 15 is switched off.
Ending start
When the engine cranking speed has reached 400 to 700 RPM or a starting time of about 5 to 40 s (depending on coolant temperature), the ME-SFI [ME] control unit interrupts negative activation to the circuit 50 starter relay, thereby ending the start procedure.
A voltage dip limiter (R62) is installed at the positive battery terminal. Its task is to prevent the battery voltage from dropping below a defined value during the starting procedure. This is performed through temporary limitation of the starter current.
Note here that a voltage of 12 V is only present at the starter positive line during the starting procedure.
| Electrical function schematic for starting | Engine 177.9 in model 205, 253 | PE07.10-P-2701-97FBD | |
| Engine 177.9 in model 213 up to model year 2021 | PE07.10-P-2701-97DBG | ||
| Overview of system components for gasoline injection and ignition system with direct injection | Engine 177.9 in model 205, 253 | GF07.70-P-9998MNA | |
| Engine 177.9 in model 213 up to model year 2021 | GF07.70-P-9998MNE |