Function requirements for ignition OFF, general points
Circuit 87M (Engine management ON)
Circuit 15 (ignition ON)
Ignition OFF, general points
With the ignition OFF, first the engine and then the engine management are switched off in the ME-SFI [ME] control unit (N3/10).
Function sequence for ignition OFF
For ignition OFF, the engine compartment circuit 15 relay (K40/8kG) is switched off by the electronic ignition lock control unit (N73) via interior CAN (CAN B) and the front SAM control unit (N10/6). The "Circuit 15 OFF" signal is sent redundantly via suspension FlexRay (Flex E) to the powertrain control unit (N127) and via drive train CAN (CAN C1) to the ME-SFI [ME] control unit.
The "circuit 15 OFF" signal is led at the same time via the chassis FlexRay, the powertrain control unit and via the hybrid CAN (CAN L) to the power electronics control unit (N129/1) and the battery management system control unit (N82/2). The "open contactor" request is sent by the powertrain control unit over the hybrid CAN to the battery management system control unit.
If the ME-SFI [ME] control unit receives the "circuit 15 OFF" signal over the engine compartment circuit 15 relay, the engine is switched off by shutting off the fuel pump (M3), the fuel injectors (Y76/1 to T1/4) and the ignition coils (T1/1 to Y76/4) are switched off and computer run-on is started.
Information for partial function "no-load current shutoff" is documented in the function description "Engine OFF energy management function".
The ground connection "circuit 31" takes place from the on-board electrical system battery (G1) over the battery ground point (W10) and over a number of ground lines to the left major assembly compartment electronics ground point (W16/5).
When the ignition is OFF, the ME-SFI [ME] control unit is supplied with power from the on-board electrical system battery via "circuit 30 fused".