Starting System: Description and Operation

GF15.30-P-3000MAR Starter Control, Function
ENGINE 156.981 in MODEL 230.470 as of Model Year 09 /Modification Year 08 model refinement package

Function requirements for starter control, general points
^ Circuit 87M ON (engine control ON)
^ Engine OFF
^ Drive authorization system start enable (DAS 3)
^ 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).

The ME-SFI control unit manages the starter control according to the following sensors and signals:

- Coolant temperature sensor (B11/4)
- Crankshaft Hall sensor (B70), motor speed
- EIS control unit (N73), tml. 50 signal over the engine compartment CAN (CAN C)
- Electric controller unit (VGS) (Y3/8), gear range via engine compartment CAN

Starter control function sequence
The function sequence is subdivided into the following steps:
^ Start function sequence
^ End of start function sequence

Start function sequence
When the transmitter key (A8/1) is moved to the start position, the ME-SFI control unit receives the "tml. 50 signal" from the EIS control unit over the engine compartment CAN.
It actuates the starter relay (K40/4kL) 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 an engine cranking speed of 400 to 700 rpm is reached, or after a starting time of 5 to 40 s (depending on coolant temperature), the ME-SFI control unit interrupts the negative activation of the starter relay and thus completes the start procedure.

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