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

GF07.61-P-3018MIS ME-SFI Safety Fuel Shutoff, Function
- 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 [ME] control unit (N3/10) controls the safety fuel shutoff according to the following sensors and signals:
- Crankshaft Hall sensor (B70), engine speed
- Throttle valve actuator (M16/6), throttle valve position
- Restraint systems control unit (N2/7), direct crash signal
- Restraint system control unit, indirect crash signal over the chassis CAN (CAN E)

Function sequence for safety fuel shutoff
The safety fuel shutoff is activated by the ME-SFI [ME] control unit in the following conditions:
^ Function sequence for mechanical fault in throttle valve actuator
^ Function sequence for engine speed signal missing
^ Function sequence for crash signal

Function sequence for mechanical fault in throttle valve actuator
When evaluating the throttle valve position, if the ME-SFI [ME] control unit detects a mechanical fault in the throttle valve actuator, engine speed is limited to about 1400 rpm at idle and about 1800 rpm in driving mode by shutting off the fuel injection valves (Y62).

Engine speed is detected by the ME-SFI [ME] control unit on the signal from the crankshaft Hall sensor.

Function sequence for engine speed signal missing
If the engine speed signal generated by the ME-SFI [ME] control unit fails, the fuel pump (M3) is shut off through the fuel pump control unit (N118).

Function sequence for crash signal
If the ME-SFI [ME] control unit receives a crash signal directly or indirectly from the restraint systems control unit over the chassis CAN, it switches off the fuel pump through the fuel pump control unit and briefly actuates the fuel injection valves in order to depressurize the fuel system.