Starting System: Description and Operation

GF07.10-P-1001MMC Starting, Function
- ENGINES 157.9 in MODEL 216.3, 221.0 /1
- ENGINES 278.9 in MODEL 216.3, 221.0 /1

Starting function requirements, general points
- Circuit 87M ON (engine control ON)
- Engine OFF
- Drive authorization system 3 (DAS 3) start enable
- Engaged gear range "P" or "N"

Starting, general points
For the starting, the ME-SFI [ME] control unit (N3/10) reads the following sensors and signals:
- LH and RH intake camshaft Hall sensor (B6/4, B6/5), intake camshaft positions for ignition circuit detection
- LH and RH exhaust camshaft Hall sensor (B6/6, B6/7), exhaust camshaft positions for ignition circuit detection
- Coolant temperature sensor (B11/4)
- Crankshaft Hall sensor (B70), engine speed
- EIS control unit (N73), circuit 50 signal via the chassis CAN (CAN E)

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) directly and via the drive train CAN (CAN C) and thus the fuel pump (M3)

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

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
Through moving the ignition key (transmitter key (A8/1)) into the start position, the ME-SFI [ME] control unit receives the "circuit 50 signal" from the EZS control unit via the chassis CAN.
The ME-SFI [ME] control unit actuates the circuit 50 relay, starter (N10/1kH) by means of a ground signal. 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
Start 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 (depending on coolant temperature), the ME-SFI [ME] control unit interrupts the negative activation of the circuit 50 starter relay and thus terminates the start sequence.

The start sequence can only be aborted by switching off the ignition.