Starting System: Description and Operation

GF15.30-P-3000MIS Starter Control, Function
ENGINE 272.9 (except 272.974) in MODEL 221.0 /1 (except 221.095 /195) as of model year 2009 /AEJ 08
ENGINE 273.9 in MODEL 216.3, 221.0 /1 as of model year 2009 / AEJ 08

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

Starter control, general points
Starter control which is integrated in the ME-SFI [ME] control unit (N3/10) takes over actuation and shutoff of the starter (M1).
For the starter control, the ME-SFI [ME] control unit reads the following sensors and signals:

- Coolant temperature sensor (B11/4)
- Crankshaft Hall sensor (B70), engine speed
- EIS control unit (N73), circuit 50 signal via the chassis CAN (CAN E)
- Electric controller unit (VGS) (Y3/8), gear range via the drive train CAN (CAN C)

Starter control function sequence
The function sequence is subdivided into the following steps:

^ Start function sequence
^ End of start function sequence

Start function sequence
The ME-SFI [ME] control unit receives the "circuit 50 signal" from the EIS [EZS] control unit via the chassis CAN by actuating the transmitter key (A8/1) in the start position.
This control unit actuates the circuit 50 starter relay (N10/1kH) with 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".

End of start function sequence
Start control is carried out automatically by the ME-SFI [ME] control unit (touch start). This means that if the start process is initiated switching off of "circuit 50" has no further influence on the start process.
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.