GF07.61-P-3018MLK ME-SFI Safety Fuel Shutoff, Function

GF07.61-P-3018MLK ME-SFI Safety Fuel Shutoff, Function
- refinement package
- as of model year 09


Function requirements for safety fuel shutoff, general points
^ Circuit 87M ON (engine control ON)
^ Engine running

Safety fuel shutoff, general points
To ensure traffic and passenger safety, safety fuel shutoff is applied.

The ME-SFI control unit (N3/10) controls the safety fuel shutoff according to the following sensors and signals:
- Crankshaft position sensor (L5), motor speed
- Throttle valve actuator (M16/6), throttle valve position
- Restraint systems control unit (N2/7), direct crash signal
- Restraint systems control unit (N2/7), crash signal over the interior CAN (CAN B) and engine compartment CAN (CAN C)

Safety fuel shutoff function sequence
The safety fuel shutoff is activated by the ME-SFI control unit in the following conditions:
^ Mechanical fault in throttle valve actuator function sequence
^ Function sequence for engine speed "TNA" signal missing
^ Crash signal function sequence

Mechanical fault in throttle valve actuator function sequence
If the ME-SFI control unit detects a mechanical fault in the throttle valve actuator by evaluating the throttle valve position, engine speed is limited to about 1400 rpm by shutting off the fuel injection valves (Y62).
The ME-SFI control unit detects engine speed through the signal from the crankshaft position sensor.

Function sequence for engine speed "TNA" signal missing
If the "TNA" engine speed signal generated by the ME-SFI control unit is missing, the fuel pump (M3) is shut off through the fuel pump relay (N10/2kA).

Crash signal function sequence
If the ME-SFI control unit receives a crash signal from the restraint systems control unit, either directly or over the engine compartment CAN, it shuts off the fuel pump through the fuel pump relay and briefly actuates the fuel injection valves in order to depressurize the fuel system.